CHANNEL ISLANDS

the population, according to the census of 1921, was 89,614; the effective population, 27.e., excluding visitors, was estimated at about 87,500. during the world war the islands provided a considerable number of men for overseas service. in 1917, when the im- perial govt. relieved the insular funds of the cost, previously borne locally, of the local militia, the question of a contribution from the islands of jersey and guernsey to imperial funds was raised. in recognition of this relief of their revenue, the states of jersey voted, in dec. 1917, a gift of £25,000 towards the cost of the war. in 1918 it was suggested by the british home secretary that the islands should share in the financial burden of the war, and the states of jersey made further contributions of £50,000 in dec. 1918, and £25,000 in march 1919, making £100,000 in all. in dec. 1918 guernsey made a contribution of £100,000. the question of financial aid.—in the report of the committee of national expenditure of feb. 21 1922 the committee com- mented on the fact that the islands made no annual contribu- tions to the imperial revenue, though they obtained practically the same benefits as though they were part of the united king- dom. <as taxation in the islands was very light, the committce recommended that the government might suggest an annual contribution from the islands to the imperial exchequer. in jan. 1923 the home secretary again invited the islands to consider the question. in view of the fact that no response was mide by jersey to this invitation, and that the contribution offered by guernsey was below that the government considered equitable, a committee of the privy council was appointed on march 9 1925 to consider the whole matter. the committce rec- ommended that the contributions to the imperial funds should be annual sums of £120,000 from jersey and £75,000 from guern- sey, payable for a period of 100 years.!. the states of jersey and guernsey did not accept this recommendation. jersey offered a final contribution of £300,000, and guernsey of £220,000. trade.—exports from the islands to great britain, mainly pota- tocs, tomatoes, grapes, fresh flowers and granite, are valued at about £3,500, 000 annually; imports from great britain are valued at some £3,750,000 annually. ‘the two main sources of income in jersey are agriculture and the tourist trade. imports increased in value from £1,163,811 in 1913 to £2,744,648 in 1924, and exports from {970,671 to £1,647,214. cattle rearing is of considerable importance. bisiiograpnuy.—b. b. eliott, jersey—an isle of romance (1923); e. foord, the channel islands (1924); e. f. carey, channel islands (1924). (wv. h. wl.) chantavoine, henri (1850-1918), french man of letters (see 5.847), died at galuire (rhene) aug. 15 1918. chaplin, henry chaplin, ist viscount (1841-1923), english politician (see 5.852). mr. chaplin on his return to the house of commons in 1907 as member for wimbledon was gen- erally welcomed as a type of parliamentarian who was fast dis- appearing. he intervened with effect on questions of land and of social and tariff reform, but otherwise was not so prominent in debate as in past years. when the first coalition govt. was formed in may rors, he was left almost alone on the front op- position bench, and it was felt to be a fitting close of a distin- guished career in the commons, when he was raised to the peerage in april 1916. he died in london may 29 1923. chaplin, charles spencer (1889- ), motion-picture actor, was born april 16 1889, of english parentage, and passed \ report of the committce of the privy council on the question of contributions to imperial funds from the islands of jersey guern- sey and man. (cmd. 2586.) 569 his early years in london. at an early age he appeared on the music hall stage with his father and brother sydney, taking small parts in vaudeville. after a short experience on the icgitimate stage he re-entered vaudeville in london, asa member of the fred karno company. in 1910 he went to the united states as leading comedian in a karno production, 4a night in an english mastic hall. we attracted the attention of joseph m. schenck, and on the latter’s suggestion he was engaged by mack sennett to make moving pictures with the keystone comedy company at hollywood, california. in his first picture, made in 1913, he adopted the eccentric costume which has ever since been associated with his name. his success was immediate, contin- uous and universal. in 1918 he formed his own company, and produced a series of motion pictures which placed him in the front rank of artists and in a category of his own in the field of screen comedy. among the more successful of his later re- leases were a dog’s life (1918), shoulder arms (1918), the kid (1921), the idle cluss (1921), the gold rush (1925) and lhe circus (1926). in all of these he was the central figure. in 1923 he directed, but did not personally appear in, a hwomaz of parts, a serious picture, displaying extraordinary skill in con- struction and ensemble, which has been used as a model by subsequent directors. character.—to ask what character is reveals the confusion of ordinary thought about it. instincts, habits, impulses, desires, emotions, sentiments all belong to it. but what relation do they bear to one another? what is the part of character that has to be controlled and what is its controlling part? whence come those things that are called “ principles” of conduct, and “‘ ideals,” and the multitude of ‘ qualities of character ’’—courage, stead- fastness, sincerity, tolerance, generosity, patience and honesty, and their opposites? we do not know. the first general problem of the psychology of character is therefore to transform the chaos of the ordinary conception of it into one in which the parts of character are seen to bear a clear and intelligible relation to the whole. there are certain common but useful antitheses ‘‘ character and intelligence *. “ character and circumstances ”’; “ character and conduct.” conduct is the expression of character; only actions that are in some degree under voluntary control are in- cluded in conduct. reflex actions are not included in conduct; instinctive actions are. character is the driving force; intelli- gence guides it to its destination; together they sum up the human mind and are inseparable in it. stages of character —these may be classed under three heads, which roughly correspond to three levels of mental development: (1) the instinctive; (2) the emotional; (3) the level of sentiment; and again roughly these three are represented in (1) the life of the animal; (2) the life of the child; and (3) the life of the adult human being. the first is the most perfect in organisation; but also the most rigid, in which intelligence has least formative in- fluence. the second is the most helpless and marks the transition from a lower to a higher form of organisation, for which the guid- ance of the adult mind is indispensable. the third is the most plastic and comprehensive; but its organisation is never com- pleted. in it reflection, reason and self-control have their full opportunities; yet it is the region of folly and error, with which we can hardly charge the animals; of mistaken valuations fol- lowed by disillusions; of progress and decadence; of constancy and infidelity. it has never been understood. these three, instinct, emotion, sentiment, each after its kind, are systems. as everything in the body is a system or a part of a system, so is it in the mind. reason and self-control are price- less; but they do not function in a void. they are the properties of the highest systems of the mind—the sentiments. the human instincis animal instincts are inherited dispo sitions having specific patterns of behaviour for the attainment of their ends. an impulse felt in consciousness precedes their operation; attention accompanies it, and serves to adapt the pattern of behaviour to the actual situation. ituman instincts have lost these patterns except in the case of simple instincts, as sucking, shrinking and clinging; in others the child must learn by 9/0 experience to acquire new means to replace the old. apart from these acquired processes his instincts are revealed as impulses innately determined to pursue certain ends. but with the loss of their instinctive behaviour they have become more plastic. how many ways of concealment has not man learnt! the end itself has been conceptualised. the end for an animal is perceived—a hole or cover; the end for man may be conceived—a secret thought. in this sense, as instinctive impulses defined by their ends, we can enumerate the most important human instincts. they are flight and pursuit, concealment and display, domination and sub- mission, attraction and repulsion, destruction and construction, crying for protection and giving protection, curiosity and search, and the food and sex instincts. the ends are only proximate ones, assumed to have been selected first for their biological util- ity; but in man they are also indispensable to the ends which he invents—wealth, power, fame, well-being, happiness, perfection. the instincts sometimes act independently of emotion, finding in their own impulses when unchecked the force to attain their ends; but (1) when their impulses are obstructed they tend to arouse anger or fear; (2) when they attain their ends, joy or satis- faction; (3) when they fail completely, sorrow or despair. the emotions never act independently of instincts, and tend to organ- ise in their systems all that subserve their ends. hence we find concealment not only in fear, but in the anger of revenge; in shame; in envy; in sorrow; in the joy of children’s games. this seems to be the relation between instincts and emotions. difference between instinct and emotion.—they are oiten con- fused because so often combined together. an instinct advancing to its end unchecked does not need to arouse emotion. in itself it is unlike emotion; it is most like habit. both instinct and habit are orderly and stable, showing so little variability in action that we forecast the course of it. emotion unrestrained is unstable and disorderly; its actions often surprise us. we follow our strong habits often without recognising them; they are calm and unobtrusive; we cannot help recognising our strong emotions. hence it is, when emotion and instinct are conjoined, the second as it comes into operation tends to calm the first. it is the mo- ments before action, we remark, that are so tense. for the force which emotion brings is for the needs of a certain situation. it should not therefore persist for long, and if it does, it tends to become pathological, as we see in the case of our morbid fears. but it is the nature of instinct and habit, and love and hate, to persist indefinitely. besides these differences between instincts and emotions there are those based on the nature of their systems. emotion is po- tentially more complex. concealment is only one of many in- stincts organised in fear which may choose this instinct or any other better adapted to the actual situation: flight, shrinking or clutching, or shrieks for protection. from the time of bain it has been recognised that strong emotion is accompanied by a dif- fused nervous disturbance; and this may render emotion more adaptable to a changing situation; whereas when an instinct is unchecked, and following out the normal course of its behaviour, the nervous discharge tends to be restricted to those channels which sustain this behaviour. here the intervention of emotion would be not only superfluous but harmful. the value of emotion lies in these two points of difference from instinct: (1) the force which it brings to deal with a given situa- tion, and (2) its potentially more complex and adaptable system. it is indispensable to the sentiments, and without it there could neither be love nor hate. all great ee of character are initiated by emotion. the stage of the sentiments.—whence comes the power that man has to hold up his emotions and the ideas of action they thrust upon his attention and would forthwith accomplish? that which has to exercise control must have a wider outlook than that which is to be controlled; but unless it moves us its warn- ings are ineffectual. it must move us by some other influence than emotion. the emotions cannot cure their inherent defects of impulsiveness and lack of reflection, being without self-control. self-control comes from a higher system than emotion, and one that by its comprehensiveness more adequately represents the character self. love and hate, the chief sentiments, have this comprehen- siveness. they are that governing part of character to which we have referred; and all the part which has to be governed is be- neath them, under their authority. but if the sentiments are, as we now take them to be, systems of emotional dispositions, how do these provide them with the self-control they need? joy and sorrow, hope, anxiety and disappointment, are the common lot of all of them; but there is something else in their systems. the impulses of their emotions become desires, these grow more ab- stract and general with experience, until at length the desires that change give rise to the desires that are always the same: from meetings and separations, from agreements and discords, the desire for union; from passing enjoyments, happiness and well- being; from acts of love the desire for reciprocity of love. thus love obtains its great organising desires directed to its unchang- ing ends of union, happiness and well-being of the loved object, reciprocity of love, and the desire to be happy in the love of the object. but in hate these ends are reversed: not preservation and union, but destruction and separation; not happiness and well- being, but misery and the worst possible state of the object, and yet withal, the desire to be happy in the separation, misery and destruction of the object. in these great desires love and hate find the principles of their self-control—not in their emotions. here is the governing part of their systems; the centre on which the rest depends. hence the long-continued struggle between this central part and the emo- tions, impulses and momentary desires that surge up against it from the inferior part, the imperfect self-control attained, and from its failures the birth of the highest part of the systems— its ideals. with these ideals come those familiar qualities of character—courage, patience, steadfastness, sincerity, sweetness, tolerance and generosity—some of which every love discovers anew for itself in the mirror of its own failures. these are the three parts of love, restricted in impersonal forms of the sentiment, but still substantially the same, revealing too the mixture of love and self-love in the very desire for union, reciprocity and happiness. repression.—repression is an extreme form of the self-control of sentiments. for if some of their emotions have to be regulated as being either too strong or too weak, others which are judged to be harmful in view of their ends have to be repressed. such repression of things within the mind corresponds most nearly to “ destruction ”’ of things without us. we would destroy some things in our character if we could; but we can only repress them, which means to exclude them from consciousness, and prevent as far as possible their return to it. in this sense we not only try to repress emotions, like unreason- able fears and false shames, but loves that are disgraceful or even unfortunate, and most of our hates. such repressed fears, loves and hates are now called ‘“‘ complexes.’ for as it 1s essential to a sentiment to be accepted by the subject of it, so it is essential to a ‘‘ complex” to be repressed. there are different degrees of repression: (1) those with which medical psychology deals. here the dissociation of the repressed constituents from the consciousness of the individual is so com- plete that unaided he cannot recall them; (2) those, much more common, which, though completely repressed, he could recall to consciousness if he desired to; (3) those which are imperfectly repressed, and after a certain time reinstate themselves in con- sciousness independently of his desire. to this class belong all the vices from which man struggles to escape, which, strengthened by habit, make him recognise his weakness: debauchery, perver- sions, drunkenness, gambling. repressions therefore in all de- grces have great importance for character as indicating the different ways in which self-contro) may be defective. conscience.—there is another sentiment distinct from both love and hate, which, like them, often undergoes repressions. the uniqueness of conscience makes it difficult to interpret, for there is a particular conscience belonging to all love of which its ideals are a part. this is partial to the loved object. the con- science is general, and being neither love nor hate, when it acts, it acts impartially. it has its own emotional system: a calm joy, charleroi, battle of sorrow, remorse, shame, fear and indignation; all are penetrated by its approvals and disapprovals. it is the repository of that part of the moral beliefs of the community in which the individual has been instructed and which he has adopted through authority and suggestion. it is therefore apt to differ from one person to another. but when it is a living force of character, it grows with a man’s experience of life, and through the illusions and disap- pointments of love. these impress certain ideals and duties upon his mind differently from hearsay, however often repeated. they become the most vital part of his conscience, being there freed from the partiality to which love at first confined them. and as the ideals of love are much the same in its different varicties, the most general and important duties come to be impressed, sooner or later, on most men. there are those who have to repress some part of them from remorse, and shrink from having to face it again in consciousness; but their denials of its beliefs, to which they try to make other men conform, never wholly convince themselves. thus is shewn in merest outline how the parts of character are related to one another and the whole—how the instincts, habits, emotions and desires function in the sentiments of man, and there represent the unity of his character. yet how incompletely they represent it. the potentials of his character transcend for better and worse everything that he has drawn from them to build up his actual loves and hates, and remain a perpetual enigma to him. see a. f. shand, foundations of character (1914). (a. f.s.) charleroi, battle of: sce frontiers, battles of the. charles (1839~—1914), king of rumania (see 5.925), died at the castle of pelesh, rumania, oct. 10 rgr4. charles i. (1887-1922), emperor of austria and king of hungary, born aug. 17 1887 at persenbeug, in lower austria, was the son of the archduke otto (1863-1906), and princess maria josepha of saxony (b. 1867). the death of his father in 1906 and the renunciation by his uncle, the archduke francis ferdinand, on the occasion of his marriage with the countess chotek (1900), of any right of succession for the children of this union, made him heir-presumptive to his grandfather, the emperor francis joseph. in oct. 1911 he married the princess zita of bourbon-parma. of this marriage there were several sons and daughters, the eldest of whom, otto, was born in 1912. charles’ relations with the emperor were not intimate, and those with francis ferdinand not cordial. it was only after the death of francis ferdinand that the old emperor took steps to initiate him in affairs of state; but these studies were interrupted almost immediately by the outbreak of the world war. after a period of duty at headquarters at teschen, charles commanded the xx. corps in the offensive of 1916 against italy, later com- manding an army on the eastern front. charles as e-mperor.—on nov. 21 1916, he succeeded to the throne, at a period of the most extreme difficulties. the military and economic resources of the monarchy were beginning to fail after two years of warfare. behind the front there was much shortage and suffering. anti-dynastic feeling was spreading widely, especially in slav and latin territories. charles’ programme on his accession was to combat this feeling, 1o renew the splendour of the dynasty, to achieve peace abroad and national settlement in the monarchy. with this end he made a complete change in the leading military and _ political posts in the monarchy. but the new men—except only the new foreign minister, czernin—were, unhappily, less talented than their predecessors. least of all was charles himself equal to his exacting position. he was an amiable man of excellent intentions, but his abilities were mediocre and _ his preparatory training inadequate. he jacked calmness and en- durance, and was prone to headlong, precipitate actions. he was powerfully influenced by his immediate entourage—his wife and mother-in-law—while distrusting all other advisers. but he was most bitterly—and justly—reproached for insin- cerity. not merely his enemies, but his allies too, particularly german statesmen and the emperor william, soon felt that they could not trust his word. the peoples of the danubian mon- charles i. 571 archy, moreover, gradually began to doubt his sincerity, although he did not spare pains to win them over. on charles’ accession the constitution in austria was still sus- pended. in may 10917, he summoned parliament once more. the earliest pronouncements of the slavonic deputies showed how far their separatist ambitions had advanced, and all the concessions now made to them remained fruitless, merely alienating the majority of the german austrians. in hun- gary, too, charles’ wide concessions to the magyars failed to check the growing separatist movement while earning for him the displeasure of the elements in vienna which stood by the unity of the empire and the ill-will of the non-magyars in hungary. peace proposals.—charles soon grew convinced of the neces- sity in his own interest and in that of the dynasty of securing a peace which would allow of the maintenance of the empire. yet the numerous attempts made, always with his approval and often upon his own initiative, to secure advantageous condi- tions, preliminary to a peace of reconciliation, failed. undoubt- edly charles neither could nor would consider the proposal of the western powers to make a separate peace; not only from regard for his allics, particularly for germany, but also owing to the refusal of the italian govt. to renounce any acquisition promised by the treaty of london. charles therefore in- formed germany that austria could no longer carry on war, and that germany must buy a general peace by territorial con- cessions in the west. count czernin opened up negotiations to this end with the german govt. but met with little sympathy from the civilian government, none from the supreme army command. djis- putes arose, breeding ill-will on both sides. the mistrust for charles’ sincerity entertaincd by the emperor william and his advisers increased, the tension reaching its climax after the pub- lication in the spring of 1918 of charles’ letter of march 24 1917, to his brother-in-law, sixtus of parma, announcing his readiness to support in berlin “ the just claims of france to alsace-lor- raine.” charles’ failure during the ensuing polemic openly to avow the authorship of the letter and his resort to subter- fuges deprived him of his last remnant of authority abroad and at home. in order to propitiate the emperor william and the german govt. he was compelled to accept an arrange- ment with the latter which, if carried into effect, would have rendered the monarchy entirely dependent upon the german empire. at the eleventh hour charles sought salvation for him- self and his dynasty in the manifesto of oct. 16 1918, which held out the prospect of the conversion of austria into a federal state, in which each race was to form a political commonwealth of its own upon its own territory. but the offer came too late, and was in any case unacceptable to the southern slavs, since the mag- yars had insisted on a clause affirming the integrity of the hun- garian kingdom. depariure from austria.—the disruption of the dual mon- archy pursued its way. charles now mainly attempted to protect his dynasty by means of a separate peace with the enemy; but in vain. abandoned within the empire and without, he voluntarily renounced on nov. 11 1918, all participation in the government in order, as he himself expressed it, ‘not to hinder the free devel- opment of his peoples,” but actually because he would otherwise have been compelled to abdicate. two days later he made a similar renunciation in the case of hungary. the german aus- trian republic was proclaimed on nov. 12, the hungarian on nov. 16 1918. but charles did not resign the crown of his dominions. fle retired to his castle of eckartsau; thence he went, the austrian govt. having demanded his denarture, on march 24 1919 to switzerland, where he stayed first at schloss gstaad and later at prangins. his attempt at the end of march 1921 to secure his restoration as king of hungary failed owing to the attitude of the regent horthy and other leading hun- garians and the unanimous opposition of the succession states and the entente. charles returned to switzerland, where a provisional prolonga- tion of his residence was accorded him subject to certain 9/2 conditions. disregarding his undertakings towards switzerland, he made a new attempt in oct. 1921, to assert his claims as king of hungary. having made a surprise air flight with his wife from switzerland to the burgenland, charles was there joined by a small force of armed royalists, at whose head he marched on budapest. but the allied powers, as well as the ‘‘ little entente,” at once made it clear that a coup d’etat would not be tolerated; and there was a strong rally at budapest to the side of the horthy government. the royalists were met near buda- pest and defeated, charles and zita being themselves arrested at tihany. on instructions from the powers, the definite deposition of charles and renunciation of his claims to the throne were in- sisted upon, and he and his wife were handed over to the custody of the allies forinternment. refused the right of asylum by switz- erland, on the ground that he had not adhered to the conditions agreed upon, and accorded a reception by portugal alone, he was conveyed upon the english ship “ cardiff” to funchal, madeira. here he lived in straitened circumstances until released by death on april 1 1922. bibliography.— karl werkmann, der tote auf madetra (1923); aladar von boroviczeny, der kenig und sein reichverweser (1924); r. fester, katser karl und der wendepunkte des weltkrieges (1925). charnay, desire (1828-rors), french traveller and archacologist (see 5.947), dicd in paris oct. 24 1915. chase, william merritt (1849-1916), american painter (see 5.956), died in new york oct. 25 1916. in rot2 he was awarded the proctor prize by the national academy of design for his ‘‘ portrait of mrs. h.” at the panama pacific exposition (1915), a special room was assigned to his works. chateau-thierry, a small town in the northeast of france, on the marne, 47 m. east and north of paris. it was the farthest point reached by the germans in their offensive of may 27 1918. the 2nd and ard divs. of the american expeditionary force were sent to the marne in the chateau-thicrry region to assist the hard-pressed french forces. at chateau-thierry itself a u.s. machine-gun battalion took part in the successful defence of the river crossing, while to the west of the town the 2nd div., under gen. bundy, fought the fiercely contested engagement of belleau woods. (see german offensive; marne, second battle of the.) chekhov, anton pavlovich (1860-1904), russian novel- ist and dramatist, was born jan. 17 1860 in taganrog on the sea of azov. this name is also spelled tchekhov, tchehov and chehov. his father was a tradesman and the son of a serf. the writer was educated at the gymnasium of his native town, and in 1879 went to the university of moscow, where he studied medicine. he took his degree in 1884 but practised very little (except during the cholera epidemic of 1892-3). he began his literary career while yet a student, and soon became one of the most welcome contributors to the comic papers. his early stories appeared over the signature antosha chekhonte. in 1886 some of his stories were published in book form (particoloured stories). the book had a great success and attracted to chekhov the at- tention of the publisher and editor suvorin, who became his friend and through whom chekhov was able to emancipate him- self from the comic papers and from the obligation of being a humorist. in 1887 he produced his first play zvanov. in 1890 he travelled to the convict island of sakhalin and the result of his journey was saghalien island (1891), which had a considerable effect on the mitigation of the penal regime. from 1891 to 1897 he lived together with his parents on a small estate he had acquired not far from moscow. after 1897, as he was threatened with tu- berculosis, he was forced to live the greater part of the year in the crimea and abroad. in 1896 he produced his second play, the seagull, which met with a complete failure in st. petersburg (leningrad). but in 1898 it was revived by the moscow art theatre of stanislavsky and proved a great success. hencefor- ward chekhov’s connection with that theatre became very close. uncle vanya (1899), the three sisters (1901) and the cherry orchard (1904) were produced there. in 1901 he married the charnay—chekhov actress olga knipper. in 1g00 he was elected an honorary fellow of the academy of science, but resigned his fellowship when the election of maxim gorky was cancelled by the government. he died july 2 1904 at badenweiler in the black forest. early work.—the early stories of chekhov, up to about 1886, are chiefly humorous. they are, in russia, the most widely popular part of his work, and more people know him by them than by my life or the three sisters. chekhov’s humour is not strikingly above the level of the papers he wrote for. but very early he began to lay the foundations of that manner which is the essential chekhov. such a story as the chorus girl (1884) is almost a mature masterpiece. it was, however, only after 1886 that he found the necessary leisure and independence to give definite expression to his imaginative experience. the years 1886-8 are a period of transition during which he experi- mented in various directions. to these years belong a series of stories of atmosphere against a background of nature (the steppe, happiness, easier eve) where the lyrical element of his genius received its fullest expression, and short stories of morbid expe- rience in which the knowledge of the doctor is balanced by. the sense of form of the artist. by 1889, however, he had attained perfection in his style. to this and the following years belong a succession of masterpieces, the principal of which are a dreary story (1889), the duel, ward no. 6 (1892), the teacher of literature (1894), three years: an artist's story (in russian the house with the maisonette) (1895), peasants (1897), the darling, ionttch, the lady with the dog (1898), the new villa (1899), the bishop (1902). chekhov’s art has been described as psychological, but his psychology ignores the individual. his characters are not per- sons but just men and women, the genus domo, an indifferentiated mass of humanity, divided into watertight compartments by the phenomenon of individuality, which does not make one being different from another but only inaccessible to him. <a typical story by chekhov is the life-story of a ‘‘ mood,” of a state of mind, usually of the relation of one person to another and the gradual transformation of that state of mind under the action of the incessant infinitesimal and unforeseen pinpricks of life. sen- sitiveness to these pinpricks is the main feature of chekhov’s people, of those at least who are made to kindle the reader’s sympathy, and the standard by which chekhov gauges the worth of a human being. those who suffer and succumb are the higher race, those who do not are unfeeling brutes. hence a deep-rooted aversion (present in pre-chekhov russian literature, especially in turgenev, but enormously magnified by chekhov) for the strong and efficient man. none but “ hamlets ” may receive sympathy. the construction of chekhov’s stories may be described as musical or infinitesimal. it is at once fluid and precise. they are built along exactly calculated curves, of which only certain points are marked in the story, but each two points are sufficient to calculate the whole curve. the curve is the mood which begins as almost a straight line, then under the influence of “ pinpricks ” begins to deviate and at last shoots out in an entirely opposite direction. by far the greater number of chekhov’s stories end on a minor note, ‘ not with a bang but a whimper.” a story where the direction is in the opposite way, as in the lady with the dog (where the hero begins by regarding his love for the lady as a mere insignificant intrigue and ends in self-forgetful passion), is an exception. the ‘ pessimistic,” destructive, descendant tendency of the russian novelists of the mid and later roth con- tury reaches its extreme expression in chekhov, all the more extreme as it is so consistently muffled and “ understated.” to him, better than to any one, the words of m. albert thibaudet apply, that a russian story is always the story of the undoing of a life. somewhat apart from the other stories of chekhov stand, what are perhaps his two masterpieces, af y life (1895) and in the ravine (1900). they have a clearer and harder outline; they are free from the atmospheric, autumnal haze that pervades the others, and animated by a more active sense of moraland human values. jfy life, especially, is a creation of vast and pregnant chelmsford—chemical engineering significance, with a symbolical grasp that gives it an almost reli- gious character. | chekhov’s dramatic work consists of the same element as his narrative work. it includes numerous one-act plays which were extremely popular in russia. belonging to a later period than the comic stories, they are also on a higher artistic level. the serious plays are five in number—ijvanov, the seagull, uncle vanya, the three sisters, the cherry orchard. they have many points in common with his storics; not only is his vision of life the same, but his methods are similar. one main difference is that while the stories are invariably centred round a single person from whose standpoint the situation is developed, the dramas have no such central figure, and all the characters have more or less equal rights on the stage. the plays are, as it were, sympho- nies for an orchestra of parts, and the resultant is arrived at by the complex interaction of the various voices. they are plays of “‘ atmosphere,” the english word that comes nearest to the rus- sian nastroenie(stimmung). the principal thing in them is not the action but the emotional accompaniment of the action. in the “ de-theatricalisation ” of the theatre, in the complete avoid- ance of all traditional stage effects (though he introduced a new kind of “ atmospheric ”’ effect, as the famous string (bursting at the end of the cherry orchard), chekhov is the logical limit of the preceding development of the russian drama. he did not go much further in this respect than turgenev or ostrovsky, but he built a more consistent dramatic system with a completely adequate technique. the novelist’s influence—the influence of chekhov on rus- sian literature has not been extensive. the last realists (andreyev, gorky, bunin, etc.) learned little from him, and soon after his death the rise of an entirely new movement put an end to all possibility of continuing in his tradition. his plays were imi- tated by gorky, andreyev and others, but they invariably missed the constructive principle without which the whole sys- tem is stultified. there has been no school of chekhov, and his work has to be regarded as an end rather than as a beginning. it is the swansong of roth-century russia. to the russia of to-day chekhov is perhaps more alien than any other russian writer of his rank. on the other hand, his vogue and his influence outside russia have of recent years grown immensely and were in 1926 probably neartheir zenith. england has proved particularly sensitive to his charm. he is almost universally regarded as the greatest russian writer and as the greatest story-teller and dramatist of modern times. english critics have even called him the greatest drama- tist since shakespeare. nor can there be any doubt that english literature has profited by his example as russian literature never did, and that if there is to be a school of chekhov it will be in england. the lovers of chekhov are attracted as powerfully by the man as by the artist, and will find an infinite source of joy in his letters. brstiograpuy.—the tales of tchehov, 13 vol., tr. c. garnett, (1916-22); letters a. tchehov, tr. c. garnett (1920); the notebooks of a. tchehov, together with reminiscences of tchehov by maxim orky, tr. s. s. koteliansky and l. woolf (1921); the plays of tchehov, 2 vol., tr. c. garnett (1923, etc.); letters on literary topics, tr. louis friedland (1924); the life and letters of a. tchehov, tr. s. s. kotcliansky and p, tomlinson (1925); letters of a. p. tchehov to o. l. knipber, tr. c. garnett (1926); see also l. shestov, anton tchehov (1916); w. gerhardi, anion chehov ars are mu) eo. jvi. chelmsford, frederick john napier thesiger, 1st viscount (1868- ), british administrator, born aug. 12 1868, was the eldest son of frederick augustus, 2nd baron chelmsford. he was educated at winchester and magdalen college, oxford, and held a fellowship at all souls’ from 1892 to 18099. having been called to the bar he was a mem- ber of the london school board for four years, and in 1904-5 served on the london county council. in the latter year, when he succeeded his father as baron chelmsford, he was appointed governor of queensland and he held that office till 1909. these years saw the inauguration of the new policy of replacing the repatriated kanakas by white labour. it was also a period of 573 bittez political conflict. chelmsford’s action in granting the re- quest of the premier, mr. philp, for a dissolution of parliament led to widespread agitation for the appointment of governors in australia. in aug. 1909 chelmsford left queensland for new south wales of which state he was governor till 1913. it wasa period of great development for the colony, and also of great labour unrest. chelmsford, who was created g.c.m.g. in 1912, served in india with the dorset regt. in the early part of the muropean war. from april 1916 to the spring of 1921 he was viceroy of india. during this period the system of dyarchy founded upon the joint report of the viceroy and the secretary of state, mr. e. s. montagu, was introduced. a considerable measure of au- tonomy was accorded to the provinces. the council of state and legislative assembly were to be elected, and the annual budget, with some reservations, submitted to the latter. in- dians were given representation on the viceroy’s council, and india was given the same power over tariffs as the dominions. but the new reforms were opposed by a combination of hin- dus and moslems under gandhi, and a system of non-co-opera- tion adopted, whilst the repressive legislation recommended by mr. justice rowlatt’s committee to deal with sedition provoked serious riots in guzerat and the punjab, culminating in the amritsar disturbances (april 1919). however, an amnesty for political offences accompanied the promulgation of the reforms which were gradually accepted by moderate opinion. mean- while the viceroy had also to meet a mahommedan agitation directed against british policy toward turkey. this was ac- tively supported by an afghan army after whose defeat the subsidy was withdrawn from the amir, together with the privilege of importing arms from india. the new institutions were inaugurated by the duke of connaught early in r921. on his retirement chelmsford was created a viscount and received indian orders. he was first lord of the admiralty in mr. ramsay macdonald’s labour ministry of 1924. (g.leg.n.) chemical engineering.—the branch of engineering which relates to the “‘ design, construction, erection and operation of plant and works in which matter undergoes a change of state or composition.” this definition, due to the institution of chemical engineers, is rather broad but logical. a chemical engineer should possess a good general knowledge of chemistry and physics, a special knowledge of physical chemistry and thermo- dynamics, a thorough grasp of mechanical and electrical en- gineering, and those branches of civil engineering which deal with the strength of materials and the theory of design of struc- tures. since the object of chemical engineering is ultimately economic, industrial economics and law, business management and factory organisation must be given a primary place. he must be able to devise simple and effective methods of recording operations and determining actual costs, prepare designs, specifications and estimates free from ambiguity and error, report efficiently on any problem investigated, and obtain technical information readily and compile and index it for future use. foundations in practice —the practice of chemical engineering has naturally preceded the scientific analysis of its principles. typical chemical engineering operations have been performed in certain industries to such an extent as to evolve special types of plant peculiar to those industries. the chemical engineer, how- ever, must understand the underlying scientific principles upon which such operations or processes depend, so as to be able to design efficient plant for any particular purpose, rather than to allow it to be evolved by rule-of-thumb guess work with expen- sive large scale experiments and costly alterations in construc- tion before reasonable efficiency is obtained. there is little doubt that the material rewards of scientific chemical engineering are greater to-day than any other branch of engineering can offer, while its national importance cannot be over-estimated. scientific basis —the adoption in the factory of one unit of weight and volume together with the decimal system is a first step and facilitates recording, avoids errors, saves time and makes the scientific control of processes comparatively easy. 574 types of processes —chemical engineering processes are of three general types: (a) the conveyance and storage of materials, (b) the production, transfer and conservation of heat and (c) the treatment of materials. in these processes an exact knowl- edge is required to secure the greatest industrial efficiency, and questions relating to rent, capital cost, repairs, labour and super- intendence, output, material efficiency, character of the market, etc., must be considered. unfortunately some of these conditions vary from year to year and the chemical engineer must be some- what of a seer to achieve the greatest success. trans port—transport is often the most important item of the cost of production; in the factory itself, the cost of carrying materials to a machine is often as great as that of the operation conducted. methods of weighing and measuring materials in their progress through the factory need careful study, for it is only by maintaining the highest rate of output as a uniform thing, that the best results can be obtained. flow of fluids.—in industrial practice fluids may flow in two distinct ways, usually referred to as “ stream-line ” and “ turbu- lent” flow. the former method offers advantages in certain operations, filtration, classification, separation, etc., while the latter is essential to secure the greatest heat transfer. the criterion by which it can be approximately determined whether stream-line or turbulent flow is occurring in a tube is given by d ; ; the value of the modulus “2” where 9 is the velocity of the fluid, iv, d is the diameter of the tube, p the density of the fluid and yp its viscosity. the value of the fraction is the same in any system of units and when it exceeds 2,000 the flow is turbulent. semi-fluids.—the laws governing the flow of semi-fluids such as dry sand, wheat, etc., which occupy an intermediate position between solids and liquids, must be understood. a peculiarity of such materials is that their flow from an orifice is proportional to the cube of the area of the orifice and independent of the head. the transport of fluids in factories is obviously a simple and cheap process, so that a solid material which is used in solution will be transported more cheaply and conveniently by dissolving it at once and pumping the solution to stock tanks, rather than by conveying the solid itself. transfer of heat.—the production and transfer of heat in- volves a knowledge of combustion, the study of fuels, their calorific value and intensity, while the electrical generation of heat is becoming more and more important in the development of industrial processes. the design of furnaces of different types, often a matter of rule-of-thumb evolution, involves questions of heat transmission and radiation, the factors of which are very difficult to estimate. the great diminution in density of the hot gases and the increasing importance of radiation as a factor in heat transmission, as the temperature rises, are points needing the most careful study. the loss of heat from exposed hot sur- faces by radiation and air contact may be fairly closely estimated, a factor often very important in the operation of a plant. the transmission of heat through a metal diaphragm from gas to gas, gas to liquid, saturated vapour to liquid, liquid to liquid, gas to solid, etc., varies so enormously as to demand the most careful experimental research. the transmission of heat from a gas to a gas through copper 1 mm. thick, is of the order of 5 calories per square metre of surface per hour, per one degree centigrade of temperature difference between the gases; under similar circumstances the transmission from gas to non-boiling water is about 20 calories, from liquid to liquid about 350 calories, and from steam to water about 1,540 calories. if the liquid is boiling the heat transfer may be increased greatly; it is usually at least twice and may be over four times that to non- boiling liquid. the importance in steam boilers and evapora- tors of keeping the liquid constantly boiling is obvious. again, an increase of velocity of either fluid will raise the rate of heat transmission considerably by an amount which is capable of estimation. the effects of corrosion, of deposited scale, the influence of salts in solution and of precipitates in suspension on the rate of heat transmission are matters of great industrial im- chemical engineering portance. when a gas or liquid moves over a solid surface or when a gas moves over a liquid surface there exists a film of the moving fluid over the stationary substance in which there is practically no motion. the thickness of this film is mainly re- sponsible for the great differences in heat transmission already mentioned. much chemical engineering research is necessary to elucidate these questions adequately, and great wisdom in design is necessary to secure the highest economic efficiency. solid materials —in the treatment of solid materials, size reduction by crushing, grinding and impact must be well under- stood. the relative cost of the different methods and machines and the different character of the final products must be known, for the size and uniformity of the solid material treated in a chemical operation has, in practically every case, a profound in- fluence on the cost of production of the final product. the sepa- ration of solid particles from each other and from liquids involved in the processes of sifting, electrical, magnetic, hydraulic and air separation, classification, flotation, filtration, centrifuging, etc., often determines the profitable treatment of the material. new discoveries in flotation and similar methods of separation have in recent years proved of the highest value. power.—a study of the power required for different processes is of importance and may prevent false conclusions. in size re- duction for example, the power required is approximately pro- portional to the increased surface produced, so that a simple calculation will readily show how costly it is to produce the finest powders from solid materials. many processes though well understood are difficult and costly; their avoidance or replacement by some other method of sepa- ration at some other stage of the process are important points in the economic possibilities of manufacture. again, it is a com- mon experience in technical manufacture, that a method by which one process is rendered easy may cause a later process to fail and give rise to a faulty product. processes of separation and extraction.—processes of separa- tion in which a change of physical state takes place are peculiar subjects of study to the chemical engineer. leaching and extract- ing, evaporation, distillation and condensation, drying, crystal- lisation, absorption and adsorption, etc., are processes needing the highest research. processes of extraction which formerly took twelve hours are now being carried out more efficiently in one hour as a result of chemical engineering study. evaporation is now being done in many works at one-sixth of its former cost, while distillation and condensation in certain industries are now carried on with a fuel saving of nearly 80% in comparison with the methods of a few years ago. wet distillation—the process of “ wet” distillation, 7.e., distillation by means of direct steam, is used in many industries for separating a particular substance, essential oil, hydrocarbon, etc. ii such substance does not mix with water, then each de- velops that particular vapour pressure which it would have if heated separately to the same temperature, and the sum of the vapour pressures is the pressure in the still. a study of the vapour pressure curves of each substance and the conditions of decomposition of the particular one, will give the most profitable still pressure at which to work. by this alone, materials which at ordinary pressure require 200 parts of steam to distil one part of substance, may be treated under suitable pressure by which only, say, 30 parts of steam are required. again, by a reduction of pressure before condensation has taken place, a separation of the particular substance will take place and the steam may be “boosted ” back into the still again, thus securing a further economy in fuel. | drying processes.—the drying of gases, liquids and solids is a common requirement of many industries. the study of drying and drying plant may mean a change from comparative failure to great success. the drying of gases by chemical reagents such as calcium chloride, which after absorbing moisture is itself dried by hot air or flue gases, cooled and again used, is well understood, but the use of adsorption processes for this purpose is a develop- ment in industry of the last few years. the “ gels ” (silica gel, alumina gel, etc.) are treated in a similar, way to the calcium chemical warfare chloride previously mentioned, but are free from any risk of failure through overheating and have many other advantages. the fuel saving of about 30%, produced by the use of this process for the drying of the air blast of blast furnaces is an important addition to our fuel resources. gas afasks.—the efficiency of the gas mask in warfare is paralleled by the importance of the same means in peace to re- cover benzene and other solvents from air and gas effluents, to remove sulphur from oil and to perform many other chemical functions in a physical way. the absorption of water by “ silica gel’ is so energetic, and the substance can be so readily regen- erated that its general use for refrigeration may be only a matter of time. the chemical engineering problems involved in this process are both interesting and profitable. the treatment of the air of factories to render it constant in temperature and humidity also offers a large ficld to the chemical engineer. chemical reactions —the treatment of materials in chemical reactions such as roasting, calcining, destructive distillation, electrolysis, catalysis, hydrolysis, fermentation, etc., demands careful consideration of physical, chemical and engineering factors of increasing exactitude. an examination of these processes on a laboratory scale must precede their study on a manufacturing scale. the chemist does the former and the chemical engineer thelatter. additional factors involving time of reaction, strength of materials, presence of traces of impurity, cost of materials and plant, continuous or discontinuous operation, the handling and disposal of by-products, etc., arise. great increase in efficiency can be obtained often by changing an operation from an inter- mittent, or batch, method to continuous working. afatertals—the design of plant involves the preparation of flow sheets showing the flow and expenditure of material, energy, time and labour, the experimental study of the nature and prop- erties of the materials involved in plant construction and a con- tinuous search for new materials to meet the conditions of service better than those at present in use. the name of a material, unfortunately, is no indication that it is suitable for a chemical engineering purpose. ‘‘ chemical cast iron’ is a distinct kind of cast iron, characterised by the amount of silicon, sulphur and carbon content and its treatment. other materials, alloys, bricks, compositions, cements, etc., must be specified for their work both as to composition and history if success is to be made certain. in recent years, great advances have been made in the production of chemical enginecring materials of construction, silica-ware, stoneware, glass, alloy steels, alloys, etc., all of which tend to cause modification of design. the effect of heat on the strength of materials is becoming better known every year and the pro- duction of non-scaling steels which are as strong at a white heat as ordinary mild steel at the ordinary temperature will make many developments possible which have hitherto failed. the design of the plant from the point of view of the flow of ma- terial, charging and discharging, facility of erection and repair, ease of control with a limited staff, etc., calls for experience and wisdom. lay-out.—the lay-out and construction of factories involves a knowledge of several branches of civil engineering and cannot be neglected, for the erection of buildings, heavy plant and chimneys on marshy soil is a common necessity in industry. ‘the con- struction of foundations, roadways, railways, ctc., must also be understood. in the provision of power, heat and light, the relative value and use of the different methods must be con- sidered for a sound view to be taken as to whether steam, elec- tricity, gas or water-power shall be used. high-pressure steam providing power by means of turbines which exhaust into re- ceivers from which evaporating steam may be drawn, presents the most efficient power plant in many chemical industries, while electricity gencrally provides the best method of power distribu- tion, and occasionally of heating, in process work. the use of producer or water gas for heating and other purposes must not be neglected nor the value of compressed air and hydraulic water for many purposes. finally the chemical engineer must be famil- lar with the factory acts, trade union law and all those legal points which factory managers have to face. (j. w. hy.) o75 chemical warfare.—the use of irritant and poisonous substances to diminish the resistance of an opponent is probably as old as organised warfare. ‘thucydides describes two instances of the use of burning sulphur and pitch in sieges in the pelopon- nesian war and throughout classical times and the middle ages such methods were frequently employed, greek fire being a de- vice of this kind. as war became more mobile and the range of actions increased, the opportunities for using such a weapon in its primitive form disappeared, but in 1855 lord dundonald pro- posed a scheme for burning sulphur on a large scale under favourable wind conditions in order to reduce the malakoff work during the siege of sebastopol. the suggestion was rejected on the ground of humanity. international law.—the use of toxic substances was foreseen at the hague peace conference of 1899 when the governments represented pledged themselves not to use any projectiles, the sole object of which was the diffusion of asphyxiating or harmful gases. at the hague convention of 1907 the following rule was adopted: “it is expressly forbidden (a) to employ poison or poisoned arms, (b) to employ arms, ete., of a nature to cause un- necessary sitter: g.”’ it has been ‘argued that toxic gases were not contemplated as coming within the scope of this clause, but this was not the interpretation put on it by most of the powers, and the treaty of versailles assumed that their use in any form was contrary to international law. this view was confirmed by the nations represented at the washington conference in 1922. gas in the world war at the outbreak of war none of the combatant nations had made any preparation for the use of gas or were equipped with any defence against it, but after the failure of the initial german attack and the development of trench warfare, means were sought by the germans to assist the artillery preparation for an offensive against entrenched positions, in order to get back to a state of open warfare again. proposals to use gas were made at an early date and on oct. 27 1914, shrapnel containing an irritant substance (dianisidine chlorsulphonate) were used by the ger- mans at neuve chapelle without, however, any success. they were followed by shell containing a strong lachrymator (xylyl bromide) in place of part of the charge of high explosive, which were used on the russian front in jan. 1915, when the low tem- perature made the lachrymator ineffective. the introduction of gas as an effective weapon in modern war- fare really dates from april 22 1915, when the germans dis- charged chlorine from cylinders on a front of about four m. at langemarck opposite a sector held by the french. the effect of the discharge, which came as a complcte surprise, against un- protected troops, was to eliminate all resistance on the front affected, for a depth of several miles. a similar attack was made on the canadian front near langemarck on april 24. owing to various reasons the germans failed to take advantage of the opportunity offered by these first attacks for a decisive stroke and within a few days the allied troops were equipped with a crude form of respirator and the immediate danger was over. the germans soon found considerable difficulties in combining an infantry attack with a cylinder discharge, which was de- pendent on a favourable wind. consequently they abandoned the cloud gas attack except as a means of inflicting casualties on the allies. from dec. 1915, their cloud attacks became more (langerous owing to the admixture of an increasing amount of phosgene with the chlorine, which added greatly to its toxicity, but of course the protection of the allics was improving at the same time. the allies were quick to adopt retaliatory measures: the first british gas attack was made at loos on sept. 25 1915, with cylinders of chlorine, and from then to the end of the war, fre- quent cloud discharges were made as the wind was more often favourable to the allies than to the germans. as a weapon for use in an attack, the gas shell offers great advantages over the cloud discharge, as it allows the use of a much greater variety of toxic substances and its employment is independent of the wind. the germans scored one success with. 576 lachrymatory shell in the argonne in july rors, but the french were the first to realise the possibilities of a gas shell filled with a highly toxic gas such as phosgene, with a small bursting charge just sufficient to open the shell. the french shell of this type surprised the germans in the spring of 1916 and were of con- siderable assistance in the defence of verdun. subsequently the germans modified their gas shell to the same type and made con- siderable use of them both at verdun and in the somme battle. gas in 19137.—in this year gas shell first became a serious factor in the tactical situation, as both the allies and the germans had provided themselves with considerable quantities as a result of their experience in 1916. the german shell contained mainly trichlormethyl chloroformate and chlorpicrin, toxic substances of a semi-persistent nature, the french phosgene, or prussic acid, the british chlorpicrin or lachrymators. gas shell were used mainly during active operations for neutralising the enemy’s battertes, for interfering with the movements of troops and for general harassing purposes. by firing gas shell it was always possible to compel the wearing of a respirator and especially at night this resulted in a considerable diminution of efficiency. also sudden bursts of lethal shell were fired at targets known to be occupied in order to produce casualties by surprise before respirators had been adjusted. in order to achieve this, it was necessary to set up suddenly a high local concentration of gas and the most effective weapon for this purpose was the livens projector first used at arras in march 1917. this was a crude form of trench mortar, firing a bomb weighing 60 lb. containing 30 lb. of phosgene. large numbers could be installed together and fired simultaneously at the same target, producing very high concentrations of gas without any warning beyond the flash and noise of the discharge and the bursting of the bombs. the pro- jector became one of the deadliest weapons of those used in trench warfare. | july 1917 is notable for the introduction of two new gases by the germans, who had seen that with the improved methods of protection, gases such as those mentioned above, which all betray their presence at once by their immediate irritant action on the eyes and respiratory tract, were losing much of their value. they therefore introduced two new substances, dichlorethyl sulphide, commonly known as “ mustard gas ’’ from its smell or as “ yperite”’ from the place where it was first used and diphenyl- chlorarsine. mustard gas was the most effective agent used in chemical warfare and it was responsible for the majority of gas casualties. owing to its slight smell it is less easily detected than other gases and although it produces no immediate sensations of discomfort, exposure to a very low concentration is sufficient to put a man out of action owing to the effects of the gas on the eyes and lungs. as the liquid has a low vapour pressure at atmospheric temperature and reacts very slowly with water, it may remain for days or weeks in the soil and continue to produce a dangerous concentration of gas wherever the temperature is high enough. in addition to its effects on the eyes and lungs, serious blisters are produced either by splashes of the liquid or by contact with ground or any object contaminated by it. diphenylchlorarsine, a solid melting at 46°c., when finely divided in the air causes sneezing, irritation and intense pain in the nose and throat and nausea. there is a slight delay in the onset of the symptoms. bottles of this substance were embedded in high explosive shell, so that on the burst of the shell! it is scattered as a fine dust in the air. unless respirators are pro- vided with a special form of filter they may be penetrated by these small particles and the resulting sneezing may compel the removal of the respirator. however, this did not occur in the held of battle. gas 1n 1918.—for their offensive in 1918 the germans made great use of gas shell on which they relied to produce rapid neutralisation of the allied artillery, thus enabling them to reduce the length of their preliminary bombardment to a few hours without previous registration. as much as 80% of gas shell was allotted for some tasks. the gas shell available at this date can be divided into two classes from the point of view of tactical employment in an attack:— chemical warfare (1) shell containing liquids such as mustard gas, which may per- sist for long periods in the soil and cannot be used on ground which it is intended to attack or occupy. (2) shell containing volatile liquids such as phosgene or diphos- gene, or non-volatile solids such as diphenylchlorarsine, which owing to their low persistence may be used immediately before an attack. the germans used shell of the first class on the flanks of the attack and in other sections of the front to produce casualties, while the preliminary bombardment before each attack was mainly with gas shell of this second class, which compelled the continuous wearing of the respirator and added greatly to the strain and fatigue of the troops and interfered with movement and communication. the weather conditions in each offensive were suitable for gas shell except on july 15 when the attack failed. the allies also were using large quantities of gas shell in 1918, including mustard gas alter june, and so effective had they proved for various tasks, that the proportion of gas shell was steadily increasing. it is noteworthy that no gas was used in naval actions during the world war, or from aircraft. gas as a weapon.—the use of gas has added many complica- tions to war. it compels all troops to carry a respirator involvin g additional weight of equipment and training. the presence of gas compels the wearing of the respirator, thereby reducing a soldier’s efficiency both by the interference with vision, speech, etc., and by the added fatigue, and the respirator cannot be worn for long periods without arrangements which admit of eating and drinking. also the possibility of a gas attack increases the strain on troops both by the constant watchfulness that is necessary and the moral effect of gas which cannot be neglected. gas accounted for a moderate porportion of the casualties in the war. during the last year of the war 16% of the british casualties were due to gas and 33% of the american casualties, but its tactical value cannot be judged by casualties alone; it proved invaluable in the neutralisation of artillery, interference with movement and hampering communication. also, by the use of a persistent gas like mustard gas, it was possible to make a position untenable except at the cost of heavy casualties; this occurred at bourlon wood in nov. 1917 and at armentieres in april 1918. in such ways gas proved itself a valuable auxiliary to existing weapons. again, a heavy gas would penetrate into the deepest dugout which was immune against high explosive or shrapnel, and gas shell might be effective without getting a direct hit, as the gas from each burst to the windward of a target would drift over it. and above all, gas always carries with it the possibility of surprise. types of gas used.—the gases used in war can be classified roughly as follows according to the predominant effect which they produce on the body, although many gases may belong to more than one class:— (1) acute lung irritants, e.g., chlorine and phosgene, which exert an intense irritant action on the respiratory organs leading to acute pulmonary oedema. (2) lachrymators, ¢.g., xylyl bromide, which even in low concen- trations make vision impossible by their irritant action on the eyes, although the effect may not outlast the exposure to the gas. (3) paralysants, e.g., prussic acid, which in sufficiently high con- centration cause death almost instantancously by their effect on the nervous system. (4) sensory irritants of the eyes, nose and upper respiratory passages (also called sternutators as they often cause sneezing), e.g., diphenyl!chlorarsine; these are often effective in very low concentra- tions causing intense pain in the eyes, nose and throat, nausea and subsequent depression. (5) vesicants, e.g., mustard gas, which cause inflammation and blistering of the skin, eyes, and respiratory tract, the effect being produced as a rule some hours after exposure. broadly speaking, the gases in groups (1) and (3) may be re- garded as lethal agents, those in groups (2) and (4) as putting a man out of action immediately though temporarily, while the vesicants are delayed in action but have a great casualty pro- ducing power, even when used against troops trained in de- fensive measures. the following tables give the principal gases used in the world war with a brief summary of their important characteristics:— ~ 7h. i) x chemical warfare roe | | approximate ude ines | concentration eae boilin to incapacitate used by geste date of pane: per aa breathed for we rah substance chemical formula intro- - , _ | more than one | 5: duction cegrees few seconds | or two minutes) £ =lrench centigrade owing to , g = germans lachrymation | would cause | . + bis actual damage | | bones to the lungs acute lung jrritants chiorine . : ; a), folks iqls — 33:6 | 1:10,000 >1:10,000 bfg phosgene , . | coc | iqi5 +8 i :100,000 i :50,000 beg trichlormethyl chloroformate . | cl-coo-cci; 1916 +128 i :200,000 i 50,000 fg chloropicrin ' . | ccelno, 1916 +112 1:200,000 150,000 bfg (cumulative) lachrymators xytyl bromide . ) chis ce li, chebr iqi5 | +218 | 122,000,000 | a, (5 ethyl todoacetate . cilicooc,. fh, i9ig +180 15,000,000 150,000 br paralysants hydrocyanic acid . hcn 1916 +26:5 >1:2,000 no cumulative | bf sa aaa action fata sensory irritants of eyes, nose and chest (sternutators) diphenylchlorarsine (cok ig joasc! 19i7 +333 < §:10,000,000 1:50,000 g (m.p.- 43) | diphenylcyanarsine (cols )oascn 1918 mp oe <1:10,000,000 1 :50,000 cg a1.e.-- 31 ethyl dichlorarsine coh, ascly 1918 +156 1:500,000_ |_1:20,000 g vesicants dichlorethyl sulphide (mustard . gas). , , (chic) ch 2).s 1917 --217 1:1,000,000 | bf g (m,.p.+14) with 60 min. | | | exposure methods of liberating gases.—the method selected for liberating gas depends partly on the object to be attained and partly on the physical properties of the gas. gas can be discharged :-— (rt) from cylinders as cloud gas; (2) from projectiles, e.g., shell, trench mortar bombs, or projectors, either as a true gas or in the form of liquid drops or as a fine dust; +3} from aeroplane bombs as from other projectiles; 4) as a spray from containers carried in aeroplanes or tanks. cylinder or cloud gas attacks were made by installing a large numbcr of stecl cylinders containing compressed gas in the front line trenches, and discharging these in a suitable wind so that the gas was carried over into the enemy’s trenches. the gas used must be denser than the air so that it docs not rise when discharged, and it must be at a sufficient pressure to ensure that the contents of the cylinders are discharged rapidly when the valves are released. chlorine and mix- tures of chlorine and phosgene were employed mainly for this pur- pose. gas projectiles contain a toxic substance and a bursting charge, and the effect on burst depends on the nature of the filling and the size of the burster. a volatile substance like phosgene forms a small cloud which drifts with the wind, while with a liquid like mustard gas part of the filling is dispersed as a cloud, but a considerable proportion will be scat- tered over the ground in or near the shell crater, and may continue ta give off a dangerous concentration of vapour for days. a solid such as diphenylchlorarsine is dispersed as a cloud of fine dust wirich drifts down wind leaving no persistent effect. similar results are obtained with aeroplane bombs. liquids can be sprayed either from tanks or aeroplanes, but in the latter case there may be considerable losses by evaporation if the drops have to fall from a great height. protection against gas.—like all other weapons gas has its anti- dote. this takes the form of a respirator which filters out toxic materials from the air before it reaches the lungs. the early patterns consisted of a pad of cotton waste dipped in a solution or sodium thiosulphate and sodium carbonate which was tied over the mouth. ‘this was replaced by flannel or dlannelette helmets dipped in various solutions, which were worn over the head and protected the eyes as well as the lungs. the measure of protection obtainable by such means is obviously very limited, and the use of a general absorbent such as charcoal has many advantages to offer. all the combatants in the world war finally adopted respirators in which the inspired air was filtered by passing through activated charcoal in a small con- tainer, with various admixtures of other substances to increase the protection against specific gases. pads of cellulose or other filtering material were added to give protection against the fine particles pro- duced by the explosion of shell containing such substances as diphen- yichlorarsine. the contaiuer was attached directly to an imper- meable facepiece held in position by elastic bands over the head so as to make an airtight joint round the face as in the german respirator, or it was carried in a haversack and connected to the facepiece by a rubber tube carrying a mouthpicce as in the british box respirator, in which case it was necessary to prevent breathing through the nose by a nose-clip attached to the facepiece. in the french respirator, which resembled the german, the inspired air passed over the glass eyepieces and prevented the depositions of moisture on them, thus securing clear vision. the ideal respirator represents a compromise between safety and military efficiency. its weight must be small, it must admit of easy carriage and rapid adjustment, and offer little resistance to breath- ing, also it must be comfortable to wear and interfere as little as pos- sible with vision and hearing. at the same time it must give a suffi- cient measure of protection against all gases likely to be encountered in the field. but the respirator alone is no guarantee of safety; the soldier must be able to recognise the presence of gas by its smell or other effects, and thus know when he needs protection. also he must be trained to carry out his duties while wearing a respirator for long periods so as to suffer the minimum loss of efficiency. apart from these measures of individual protection, there are a number of precautions which may be grouped together under the heading of collective protection. these include arrangements for giving the alarm in case of a gas attack, the provision of protected shelters in which men can remain during a gas attack without wear- ing respirators, or to which they can go to eat or drink, and the clear- ing ot gas and the decontamination of ground after a gas attack of any kind. future of chemical warfare-after the experience of the war there is a general feeling that gas may figure again in some future war in spite of international agreements, and all nations are taking steps to equip thcir troops with protection against it. gas proved itself so effective a weapon, it offers such possibilities of surprise and it can be produced so easily in the peace equipment of the chemical indus- try, that it would be rash to discount the possibility of its use under the conditions of war psychology. moreover it is difficult to main- tain that it is less humane than other weapons. for cxample, the total recorded british gas casualties were 180,983 with 6,062 deaths, whilst the mortality amongst other battle casualties was about 25 %, and it was striking how small a proportion of the gas casualties who survived suffered any permanent disablement. most forecasts of future wars assign to gas an important rele in its use from aircraft against mobilisation and manufacturing centres and even against the civilian population, and under certain condi- tions there can be little doubt as to its effectiveness. as regards its use in the field, much depends on whether the type of warfare is such as to permit of its employment in sufficient quantity and concen- tration. position warfare offers exceptional opportunities for its use, 578 but the tank and the aeroplane which favour a return to some form of mobile warfare, may themselves become the means by which gas may be discharged most advantageously. bibliography.—a. a. fries and c. j. west, chemical warfare (1921); ‘‘ diseases of the war,” oficial history of the great war: medical services, vol. 2 (1923); hanslian and bergendorff, der chemische krieg (1925); meyer, der gaskampf und die chemischen kampfstoffe (leipzig, 1925). (hh. be a cgd.) chemistry (see 6.33) is the study of the components of the universe, of its ultimate materials, a branch of natural science. in ordinary life, we judge of man’s character from his actions: so also in chemistry. the science had its beginning when man be- came a living soul and not only began to see and compare the ob- jects about him and to notice changes but also to make logical constructive use of his observations. fire.——fire, in the form of the sun, must have been his first wonder, but the fear of fire will have come upon him by accident, we may suppose—if not from the volcano, in the thunderstorm. his appreciation of its value will have varied with the conditions under which he lived, whether in a cold or a hot climate. the north american continent is without fire, though at times visited by devastating electric displays. england is not far from mounts vesuvius and etna and close to iceland, one of the great volcanic tegions of the world, though a region of ice and snow. the english owe much to their scandinavian ancestry and, as carlyle as told us, the primary character of the old northland my- thology was ‘the impersonation of the visible workings of nature. earnest, simple recognition of the workings of physical nature, as a thing wholly miraculous, stupendous and divine. what we now lecture of as ‘ science ’ they wondered at and fell down in awe before as religion.”” our task to-day is not only to recover this attitude but to put aside mythology and elevate our science into a pure religion—the pursuit and use of truth. discovery of fire-——sooner or later, man will have sought to make fire for himself. the most primitive method is by friction—by forcibly twisting a stick backward and forward in a hole in another piece of dry wood or by rasping one piece rapidly across another. this method may conceivably have been discovered in drilling holes into stones—in making hammer heads—or through pieces of bone, etc. women early wore necklaces of rude beads and perhaps began by threading berries or flowers upon grass stems or rushes, as chil- dren do to-day, so discovering the decorative effect of colour. that red-ochre was used to decorate the body from an early period is clear from its constant occurrence among the remains of primitive man. the production of fire by friction, however, must have en- tailed a vast exercise of thought—as the heat that is generated has to be applied in raising easily inflammable material to the burning point. a second primitive method was to catch the sparks produced on striking the mineral pyrite with a piece of stone. modern travel- lers have found this method in use among the esquimaux, who actually mine the material for the purpose. we know this method came before the use of hint and steel, as pieces of the mineral have been found in the earliest cave-dwellings along with the most primi- tive flint implements: the latter method, necessarily, did not arise until the discovery and use of iron—itself one of the marvels of early human inventive power. the heat in lime.—thunder, as carlyle tells us, to our northland ancestors, was not mere electricity, as it is to us—it was the god donner or thor, god also of beneficent summer heat. savages, when they have first seen fire, have thought it to be a devil or god that bit you sharply when you touched it and that lived upon dry wood. familiar as we are with it to-day, we use it more often than not without a thought of its meaning; indeed the nature of fire has been but slowly disclosed to man, although its effects have long been obvious. some of these, we can easily picture. in england and throughout europe, wherever possible, primitive man has lived in limestone caves and excavations. one of the most inhabited parts of the island was the southeastern district where the soft limestone, chalk, prevails—in this region, indications of early human occupa- tion are everywhere present. living in such caves, man will often have built his fire surrounded by blocks of chalk, as we do to-day with any stones at hand, if we wish to boil our kettle in the open. the harmless, unobtrusive limestone will thus have been burnt (calcined) and necessarily, from time to time, lumps will have been cast out of the cave and wetted by rain. some observant person will have noticed that, when thus wetted, the lumps have burst asunder and grown hot, even giving off steam, whilst falling into the finest powder. thus for all time, the easy method of reducing limestone into powder will have been discovered. sooner or later, also, the greater growth of grass in places where the powder had been spread about will have been noticed and the use begun of lime and limestone as an agricultural fertiliser. children playing with the wet lime must chemistry have felt its caustic effect, and spilling it upon their skin clothes will also have found out its hair-removing power: hence its use by the tanner. a distinction will thereafter have been made between mjld (unburnt) and caustic (burnt) lime. many such “ simple” dis- coveries will have been made, in course of time. other stones will have been collected and burnt, just to see what happened. being burnt in contact with charcoal, metallic ores will have been reduced and thus metals discovered, such as tin, copper and eventually iron. tin and copper often occur together and their ores are very easily reduced—so it came, probably, that bronze was the first metal made, though we may suppose that the conception of metal was first excited in the mind of man by gold, which occurs native. experimental science——-chemistry, above all others, is the experi- mental science. the science began when wise men advisedly made experiments—apparently either with the object of discovering ways of transmuting metals into gold or of finding remedies for sickness, if not of lengthening life. we can almost restore the course of action followed. pyrite, being of household value, will have been collected and stored. when stored, under ordinary conditions, especially if exposed to moist air or rain, it gradually ‘‘ decays,” changing to a soft brown solid, like the rust which so easily collects upon iron that early man must have known well. as when pyrite is burnt a pungent smell is obvious, like that from burning sulphur—a substance well known from its occurrence in volcanic districts—glimmerings of the presence of both iron and sulphur in the mineral will have been ex- cited in observant minds and the foundation laid of modern methods of qualitative analysis. stored in the open, the heaps of decayed pyrite will often have been washed with rain: here and there the washings may have been collected in pools, and when these dried up, in fine weather, green glass-like crystals of green vitriol will have been deposited. glass-like substances generally were distinguished as vitriols by the early workers. they tested everything with fire, so ‘* distilled ” this vitriol and thus discovered oi?! of vitriol; later on this was made by burning sulphur under special conditions. the name oil of vitriol is still popular, though sulphuric acid is that now given to the liquid because of its connection with sulphur. no doubt, the discovery was very soon made that oil of vitriol or vitriolic ac7d was an extraordinarily corrosive substance, and its effect upon substances generally was therefore studied. when added to common salt, it expelled a vapour or spirit—spirit of salt—which was very soluble in water. to the present day, the solution is sold as spirzts of salt or muriatic acid, because of its preparation from salt (marium). vitri- olic acid was also found to act upon nitre, again a natural product often met with near to human habitations, giving rise to a very volatile, corrosive liquid, which dissolved nearly all the metals— hence the name aguafortts, still in use among jewellers, which later gave place to nifric acid. thus were foundations laid. exact scitence.—chemistry came to rank as an exact science with the introduction of the balance. the first systematic inquiry involving the use of the balance was that of joseph black, in 1755, into the nature of magnesia alba and limestone. his account isa classic, to be read by everyone who has the slightest desire to understand chemical method—for black’s method is our modern method and it is to him, more than to anyone else, that we owe the introduction of the logical quantitative spirit into our subject, though it was not until lavoisier had made firm the foundations laid by black that the force of the method was fully recognised and its use became systematised and established. let us endeavour, as far as possible, to put ourselves into black's position. to-day, when cement is so much used in place of lime as a building material, and few of us see lime slaked to reduce it toa fine powder before mixing it with sand, we may best open our inquiry by procuring several lumps of limestone and—if we be unable to make it ourselves—of the lime made by “ burning ” it and begin by slaking a lump of the lime, laid upon a plate, first weighing the lime. as it is always well to deal with known quantities, we may also take a known amount of water. tins are at hand everywhere and it is easy to beat out a spout at the edge of a small tin box and to weigh this, say, half-full of water. pouring the water over the lime but down a rod—a pencil will do—to prevent spilling, distributing it evenly and allowing it to soak in before adding more, we stop when the lime is visibly wet. soon, if not at once, the block grows hot, begins to crack and fall to pieces and much steain is given off. the change is marvellous— that cold water should so produce heat is astonishing! what has happened? !s the water all got rid of as steam? on weighing the cold slaked lime, now a fine, dry powder, it appears that from ioo arts of lime and x parts of watcr, there is produced 100+¥ parts of the slaked lime, only x—y parts of the water having been given off as steam. so the lime has, in some way, been joined to water and apparently the heat has been produced as a consequence of the act. limestone never behaves in this way to water—what happens then when it is burnt to lime? what is the effect of burning things? usually they are more or less completely destroyed. is the limestone? experiment shows that, when strongly heated, all limestones lose in weight, some as much as 42-43 %. the cleaner the limestone, the more it loses, the best whiting (so-called because it is used in making whitewash), prepared by levigating finely ground chalk, losing the chemistry most. sometimes, in limestone rocks, crystalline masses and even crystals are found of the mineral calcite; this also appears in limestone caves in the form of stalactites. when this is burnt, it not only gives lime but more than any other form of limestone. when every pos- sible care is taken to be exact, the amount obtained 1s constantly— within the limits of experimental error—56 °, by weight of the calcite; so 44 % is in some weed lost! precise determinations of the amount of water taken up by the 56 parts of lime so produced show it to be the merest trifle above 18 parts. what of the 44 that are lost in “ burning ’’ the limestone? tesis of calcite.—as calcite is thus found to have a definite com- position and seems to be a pure limestone, the term may be used in preference to ‘‘ limestone,”’ which is the name not of a mineral species but of a rock that is found all over the world. how is it to be tor- tured into displaying its character? its actions must be studied in full. as it is deposited as stalactite by the evaporation of water which has drained through limestone rock, the material must be soluble to some extent even in water. solvents more powerful than water are known—do these affect it? muriatic and nitric acids dis- solve it readily but with effervescence—.e., gas is given off, calcite gas, let us call it provisionally: how much? the experiment being made in an apparatus which can be weighed before and after the escape of the gas, this also being collected and measured, it is found that 100 grammes of calcite afford about 44 grammes of gas and that these 44 grammes of gas measure about 22 litres. the missing 44 are thus caught and shown to be a gas—no wonder that when limestone is burnt nothing is seen to escape. what of lime? is lime soluble in acid? experiment shows that it is and that, as was to be expected, it dissolves without effervescence. it is thus made clear, that a gas is imprisoned in limestone which may be expelled by heating and also by means of acid. hence the name “fixed air,” used by black. what is this gas, this fixed air? is it one of the gases we know? we know air—we feel it as wind—though we do not see it. everyone knows vaguely that air is life—that we inhale it and that we are kept warm by its use; it is also known that fire is in some way promoted by it: that burning involves an interaction of air and the fuel. some few have learnt that less than 150 years ago the discovery was made, that the active constituent of air is the gas exygen, of which there is nearly 21°, all but about 1% of the remainder, as we now know, being nitrogen, which is inert. today, oxygen is produced in large quantities by liquefying air under pressure and separating the oxygen and nitrogen by distillation, just as we separate, for example, alcohol from water or petrol from crude petroleum. to compare these gases with calcite gas, we may ascertain the weights which have the same volume as the 44 parts of this gas obtained from 100 of calcite— the weight of the oxygen is 32, that of the nitrogen 28. oxygen.—oxygen being thus easy to get—it is used on the streets from big iron cylinders into which it has been compressed, in welding iron rails by the oxy-acetylene blowpipe—we may test its behaviour in promoting burning. anything which burns in the air, if kindled and introduced into oxygen, burns far more easily, often with great brilliance and energy. wood, charcoal, coal, oils and alcohol all burn but only the flame is conspicuous: there is neither visible nor obvious product. sulphur, used of old on matches, because it is easily fired, evidently yiclds a product, judging from the smell that is noticeable. phosphorus, which burns with great brilliancy, yields a white solid. why the name oxygen? the terminal gez is an indica- tion that it is a generative material. the name was devised by the great lavoisier—who was decapitated by the french revolutionaries in 1796, because the kepublic had no need of savants—to express the fact that common combustibles were converted by it into ae:ds, from the greek oxys, acid, gennao, to produce. oxygen remains, to-day, the most significant term in chemistry. lavoisier’s prescience in selecting it was absolute. the white snow from phosphorus, the fumes from sulphur, dissolved in water, taste acid and turn a vege- table blue colour, such as violet-juice, red; what of the product from charcoal, if there be one? on kindling charcoal in a current of oxygen and passing on the gas into a solution of blue litmus, the solution is reddened, though not made red. all vegetable matters, when burnt, together with more or less water, give a similar product, in that it is weakly acid. what of the gas from calcite? passed into a solution of litmus, it causes faint reddening: at least a clue to its nature is thus obtained. that it is to be connected with coal or car- bon was known at an early date—not only to black but to his fore- runners, let us now consider how the connection may be established. calcite, we have seen, is easily resolved into lime and calcite gas. can the gas from calcite be reunited with lime to reproduce cal- cite? though but slightly soluble, lime is more soluble than calcite: jime-water has long been used medicinally: so if the ime in lime- water were to associate with the gas, when the two are brought to- gether, the reproduced calcite might become evident by falling out of solution as it was formed. on passing the gas from calcite into lime-water, a white precipitate is formed. having ascertained the solubility of lime, it is easy to prepare enough lime-water and from this make enough of the product to find out whether it can be burnt to lime and, if so, what percentage will be lost, also how rouch gas be set free on dissolving it in acid. the values agree with those obtained with calcite—moreover, seen under the microscope, the crystalline form of the product is like that of calcite. it being thus established o79 that calcite can be reproduced from the two substances into which it is resolved by “‘ burning,’ lime-water becomes a test for calcite gas. on burning charcoal or other ‘‘ carbonaceous ”’ material in oxygen and passing the product into lime-water, precipitates are obtained which prove on examination to be calcite, being like it in crystalline form and in composition, 100 parts yielding 56 of lime and 44 of gas. it is thus discovered not only that carbon is a constituent of limestone but that calcite gas contains both oxygen and carbon: the propor- tions in which these are associated are found, by burning known weights of carbon, to be as 12 to 32 in the 44 parts of gas obtained from too of calcite. as equal volumes of the gas and of oxygen weigh as 44:32, the gas may be said to contain its own volume of oxygen. it is now possible and desirable to use the more significant name carbonic acid gas, in place of calcite gas. having thus resolved limestone into three components, lime, car- bon and oxygen, we may ask, what of lime? what happens when it is attacked by, say, muriatic acid? this latter is a solution of the spirit of salt in water—take away the water, which is known to have but a slight solvent effect upon lime, what will be the action of the spirit of salt? on passing the gas from salt through a tube containing lime, this grows very hot and gradually liquefies; ultimately, with care, a liquid may be distilled off. on examination, this behaves exactly as if it were muriatic acid, a solution of the ‘‘ spirit’ in wafer. apparently, water has been produced from the two interacting materials—what is water? what else is formed? the tube contains a solid, looking much like fused common salt. is this ‘‘ muriate,’’ perhaps, common salt? if so, it should behave like salt and give spirit of salt when “tortured ’’ by vitriolic acid. the experiment being tried, spirit of salt is found to be given off—but the residue differs from that ob- tained on thus treating salt, being but slightly soluble in water. the product from lime and spirit of salt is, in fact, a muriate, a sea-salt like substance—a haloid—but not sea-salt. when the ‘vitriol’ from the lime is studied, it is eventually found to be the well known common mineral gypsum, which thus becomes connected with limestone. clearly, something passes from the spirit of salt to the lime—does the reverse happen, perhaps? is it a case of exchange? what is water? what is spirit of salt? such questions were only recently answered. the compound nature of water was not suspected until towards the close of the 19th century. priestley, in 1781, observed that ‘‘inflammable gas,"’ as it was then called (made by dissolving iron, zinc or tin in muriatic acid), gave dew when exploded with air. cavendish, repeating the experiments, came tothe conclusion that the dew was plain water and subsequently produced water by exploding inflammable air with oxygen. even earlier (1776), macqucr, in france, had recognised that water was produced on burning inflammable air, lavoisier then studied the matter fully and eventually gave the name /ydrogen (water-preducer) to inflammable air. the first step toward proving that spirit of salt was a compound was the accidental discovery of the gas we now call chlorine, by scheele, in 1774, on dissolving a new mineral (manga- nese) pyrolusite, which he was examining in ‘‘ marine ”’ or muriatic acid. gay-lussac and thenard subsequently showed (1809) that hydrogen was produced on passing the gas spirit of salt over heated iron, and that spirit of salt could be formed by the interaction of equal volumes of hydrogen and chlorine gas (cf. t. m. lowry’s iistorical introduction to chemistry). the caustic alkalies—the production of water from lime and the spirit of salt or hydrogen chloride is, therefore, a proof that lime ts an oxide —of what? the nature of the caustic alkalies was scarcely suspected until davy, at the royal institution, in 1807, obtained the metals potassium and sodium from caustic potash and soda, by decomposing them by an electric current. limestone had fong been classed with the common alkalics—soda and potash. loreover, lavoisier had conjectured that the alkaline earths (lime and baryta) were compound substances and like metallic oxides. this view was confirmed when davy prepared calcium from lime (1808). the 56 parts of lime in 100 of calcite are now known to consist of 16 parts of oxygen and 40 parts of the metal calcium. as no further simplifica- tion can be affected by the means at the disposal of chemists, nor even by any mental process, the conclusion has been drawn that oxygen, carbon and calcium are simple matcrials or elements—within the meaning of the act chemical, the act in which an element is de- fined as a chemically unresolvable substance, for chemists are ruled by acts, taking the percentage composition of calcite into account, 2¢ is noticeable that the ratio in which oxygen is present in the two 9xides is 16 : 32=1 :2, which justifics us in speaking of lime as a te (calcium oxide) and of calcite gas as a dioxide (carbon ioxide), a vast‘amount of labour has been expended in determining the composition of water—the quantity obtainable from 56 parts of lime is 18-016, of which 16 are oxygen and 2 x1-008 hydrogen. to pro- duce this amount of water from lime, hydrogen chloride (spirit of salt) must be used in the proportions of 56 of lime to nearly 73 of chloride. the amount of chloride used contains 2 x1-008 of hydro- gen and 70-92 of chlorine, calcite, we have already seen, is a sub- stance of unvarying composition. such valucs found an interpretation in the doctrine proclaimed by the latin lucretius (b.c. 99-55) in his celebrated poem ‘‘on the 580 nature of things.’’ the doctrine was borrowed, in the main, from democritus, a greek philosopher (c. 460-380 b.c.). lucretius taught that everything was formed of indivisible particles or atoms, eternal and unchangeable; these atoms, ‘ by various combinations, in in- finite time, with the void in which they move, formed the universe.” the doctrine was resuscitated and developed by john dalton in 1808; to-day it is the accepted, proved basis of chemistry. matter is known to us in the three states of gas, liquid and solid. in the true gas, the particles are practically independent and very far apart, yet, as they are in very rapid motion, the distance they are apart is constantly varied and they often come into collision; they also constantly come into collision with any object exposed to their blows. gaseous pressure is due to the impact of the particles upon the surface affected. there is a temperature—the critical temperature—above which no pressure will cause a gas to liquefy: below this temperature, if a gas be compressed, ultimately its particles are brought sufficiently close together to exert an inherent attractive force—more or less powerful, according to the nature of the gas. the gas then liquefies. when the liquid is sufficiently cooled, it becomes solid and crystalline: the particles then take up certain definite positions. avogadro's theorem.—avogadro, in 1811, was the first to enunciate the view that the similar behaviour of gases, under comparable conditions, is to be explained by the assumption that eg#al volumes contain equal numbers of particles: consequently, the relative weight of the particles or molecules are as the relative weights of equal volumes at the same temperature and pressure; #.¢., as the densities of the gases. taking hydrogen and oxygen, for example, the latter is found to be 15-880 times as heavy as the former. having acquired a strange affection for the number 16 in connection with oxygen, having so often to deal with oxygen in their analyses, chemists have preferred to retain this number and to raise that of hydrogen to 16 15°88 practically every other respect—being the lightest of known elements. though oxygen molecules are thus determined to be about 16 times, nitrogen about 14, carbon dioxide about 22 times as heavy as hydrogen molecules, it in no way follows that these are more than the relative masses of the molecules. reflection shows that avoga- dro’s theorem has important consequences. if we consider com- pounds, taking water as the most familiar, the gas obtained by vaporising water (dry steam) is only 9 times as dense as hydrogen under comparable conditions. we know that of 9 parts of water, one is hydrogen, whilst eight are oxygen. the oxygen molecule, however, is 16 or 2x8 times as heavy as the hydrogen molecule—so that if there be one particle of oxygen in a molecule of water, there must be two particles of hydrogen. asa matter of fact, we know that when water is formed, by exploding a mixture of hydrogen and oxygen, twice as much hydrogen, by volume, as of oxygen is required—twice as many molecules, therefore, of the one as of the other interact. as the volume is diminished by a third during the explosion, the number of water molecules formed must be only two-thirds the number of hydrogen and oxygen molecules concerned in their production — some division of both molecules, some new association of their parts, must have been effected. i[t is thus discovered that the molecules have parts: how many? we may ask. [¢:xtending the inquiry to the formation of other compound gases from hydrogen, taking spirit of salt or hydrogen chloride, this is found to contain hydrogen and chlorine in the proportion of 1-008 : 35-46. the density of the gas, however, is only about r3=22, compared with that of hydrogen: a = 1-008, although hydrogen is their unit of reference in value, however, one-half of the minimum value (1-008+35-46) which can be assigned to the amount containing the unit weight of hydrogen. interaction of hydrogen and chlorine gases to form hydrogen chloride, moreover, takes place between equal volumes, without change of volume. therefore, the two molecules must be supposed to have been each divided into two, one half of the one going to one half of the other: each molecule is a similar composite, the product being a dissimilar composite. it is as if a couple, say, two lively boys, dancing in a ball room, were to meet a dissimilar similar couple, say two sedate girls, and the two couples exchanged partners: there would still be two couples dancing, their joint effect in the room in occupying the floor would be the same as that of the original two couples, though they might be less agile than the one of these and more agile than the other. chemists have chosen to term the ultimate constituent of the mole- cules, atoms. the chemist to-day constantly applies the term mole- cule to the kinetic unit —the dancing couple, the term atom being reserved for the ultimate chemical unit. physicists, thus far, have not made up their minds to use the terms consistently. the atoms, as in the case of mercury, for example, sometimes elect to dance alone, as molecules. molecules are not necessarily complex units. emphasis may also well be laid here upon the fact, that the molec- ular weight of any uniform substance, in the gaseous state, relatively to that of hydrogen, is arrived at very simply, hydrogen being taken as the unit of gaseous density, by doubling the value of the gaseous relative-density. moreover, representing the hydrogen molecule as hz, as 2 grammes of hydrogen occupy 22-32 litres at 0° and 760 mm. pressure, the gramme-molecular proportion (the molecular weight in chemistry grammes) will occupy 22-32 litres. equations written in terms of molecules can, therefore, be at once read in gaseous volumes, as well as in mass proportions. symbols.—the entire system of atomic weights and of chemical formulae rests upon the foundations afforded by avogadro's theorem, each element is indicated by a special symbol, wherever possible the initial letter of its name—as h, hydrogen, c, carbon, o, oxygen, cl, chlorine, ca, calcium. this symbol represents an atomic pro- portion and with it is always associated a certain numerical value— the atomic weight, 7.e., the smallest proportional weight known to be present in any molecules of the compound, hydrogen being given unit value, thus— hydrogen h =1-006 chlorine cl=35-46 carbon c=12 sulphur . s=32 nitrogen n=1i4 calcium . ca=4o oxygen o=16 properties of elements.—the properties of an clement are not to be defined in terms of any one set of measured values but from its behaviour generally—in fact, the portrait of an element is a great composite into which much must be read that cannot be expressed in exact terms. chemistry is an art as well as a science and, as in all walks of life, few of its adherents have the artistic sense sufficiently developed to be able to appreciate fully the works that may be set out before them. to give an example. we deduce the properties of the element oxygen, not from the gas as we know it—which indeed is itself an oxygen compound o.—but from the behaviour of this and all other oxygen com- pounds. we probably come far nearer in water and in ozone to what would be the behaviour of oxygen-stuff if it were alone than we do in that of the gas oxygen upon which we live. it were far better if we had distinct names for each of the stuffs we think of as an element, and for the compounds which the atom forms with itself. we are told that the diamond consists of carbon, but the conception the chemist has of atomic carbon (carbon-stuff) is as far removed from diamond as any two concepiions possibly could be. no elemental name could be more appropriate than that of azote, given by lavoisier to the inert gas in our atmosphere—no name better for the stuff of which it is composed, one of the most active known, we have reason to believe, than that he had in mind, though unfortunately he did not know enough to justify him in proposing its use: aminogen. ordinary oxygen gas were far better spoken of as azote—unfortunately the name is unpalat- able. chlorine is a particularly fit name for the gas we so-call; the name chlorhalogen (green salt-forming) would be more suit- able for the atomic component of its molecules were it not that it lacks euphony. diverse properties of the elements ——some of the elements are gases, very few are liquids, most are solids. some, the majority, are metals—a term that needs no special explanation; some are very different from metals, mon-metals; some show a half-way behaviour, whilst looking like metals—these are called metal- loids. in all about 90 are known. it is being said that only 92 are possible. the elements are not only thus divisible into three types but into families. —the members of human families tend to be more or less alike in their general conduct—though very different maybe in some particulars; indeed we class animals and plants in families because of resemblances—what is more, we think of the members of a family as genetically related. the lion, the tiger, the leopard, the domestic cat are all cat-like, we call them all felidae. hydrogen stands alone in the esteem of chemists—it is jove: they have made it their unit of adoration, they measure the loves of other atoms by comparing them with the hydrogen atom. oxygen, however, 1s the most potent of all the elements; its character is the most marked, it is the most full of energy and shows the widest range of affection for other elements—few decline to be associated with it; it compels all the active non-metals, except fluorine, to join with it in forming acidic compounds; it marries with all the metals to form com- pounds which neutralise the acids, alkylic (alkaline) oxides— though if the metals be allowed sufficiently to satisfy their polygamic tendencies towards oxygen, they are in the end over- come by it and the outcome of the union is acidic; it also has particular affection for itself. the halogens—as to families, chlorine—the major con- chemistry stituent of common salt—is one of a family of four halogens: fluorine, chlorine, bromine and iodine. they are a striking company, in so much as they are all more or less coloured and directly offensive to the nose and animal tissues, being highly corrosive and poisonous. their chief chemical peculiarity is their ability to enter into association with hydrogen, atom for atom, forming the hydrides iif, hcl, hbr, hi. these are all colour- less gases, very soluble in water; though not acids themselves, they form acids when thus dissolved. ‘the halogens form com- pounds with the metals generally. the oxygens.—oxygen is remarkable among the elements as the dominant parent of water. this is commonly represented as a neutral substance and appears so to us, because it is so much a part of ourselves: actually it is the most universally active and potent of known compounds. with it are to be associated, as members of its family, though somewhat distant relatives in many of their characters, the elements sulphur, selenium and tellurium., these all form hydrides characterised by powerful odours, analogous to hydrone, oh2, the unit-molecule of water, in composition; they also form a series of corresponding aciclic oxides, so2, sos3, etc. they combine with the metals generally. aminogens.—lavoisier hesitated whether he should not give the alternative name nifrogen to the chief constituent of air. in selecting azote—a name which the french have logically pre- 581 several families are to be distinguished. the sodium family containing lithtum (7), sodium (23), potassium (39), rubidium (85-4) and calcium (40), is characterised by the fact, that they are all soft metals which act vigorously upon water, liberating hydrogen and forming hydroxides, such as caustic soda (naoh) and its analogues. they all unite with the halogens, forming halides or haloids similar to common salt, nacl. the metals of the calcium family, calcium, ca, strontium, sr, barium, ba, are also soft and readily attack water, forming hydroxides resembling “ caustic lime ” ca(oli2), and combining with the halogens to form dichlorides, cacl, ete. in fine, if the symbols of the elements generally be written in a continuous series, in the order of their atomic weights, it is obvious that throughout the series there is a progressive altera- tion in properties, accompanied by a periodic rise and fall, cer- tain properties reappearing at intervals throughout the series. this peculiar relationship was specially insisted upon by the russian chemist mendeleefi and is commonly referred to as mendeleefi’s periodic classification. this periodicity comes out most strikingly when the volumes calculated as occupied by atomic proportions are contrasted with the atomic weight, and also when comparison is made of the variation in the heat- capacities of the elements at the boiling point of hydrogen (—253°), as in the following diagram:— 8 80 6 60 atomic volume “o’ atomic i fo al a at lsc specific heat “+” i} ty 4 at 50°a ' dp 40 1 se ; + we 2 ~ ®t & 7 2) 1. ; eee 196 ° i & by ex ge a q 10% ! “4 ges - se by ata peg : 0! peer ee we (" li mage voters, rt cl kca ti vcrminfenica cuzn ga as sebe rb se zr nbmo rn rhpdag cd in snsb =i te cs balacedy ta w ge irpraulg tl pbbi th = ur 0 20 40 60 80 100 120 140 160 180 200 220 240 fic. 1. diagram showing periodic variations of heat capacity and atomic volume. ferred to the present day—he recognised the peculiarity which renders it of value as a diluent in our atmosphere. recognising the remarkable properties of ammonia, he was inclined to use the term aminogen, but was eventually led to select nitrogen, because of the relation of the element to nitre and nitric acid. at that time, little was known of the great part played by nitrogen in nature and of the existence of ammonoids derived from other elements. nitrogen ts to be associated with the elements phos- phorus, arsenic and antimony, because these all form hydrides like ammonia, nhs3; they also form acidic oxides and acids like those formed from nitrogen. carbon is a host in itself, the most wonderful of all elements, in giving rise to a vast number and variety of compounds, all of which may be regarded as built upon the single simple founda- tion stone afforded by its lowest hydride, ch4, methane or marsh gas. it is usual to associate it with silicon and titanium, par- ticularly because of the analogy in the empirical composition of the oxides; the relationship is a distant one, however. methane is an entirely neutral substance. metals ——the non-metals are distinguished, speaking gen- erally, by the formation of simple gaseous hydrides. the metals are not to be thus characterised, though hydrides of many are known. they are to be recognised rather by their behaviour towards acids, from which they displace hydrogen, forming salts; also by combining with chlorine and with oxygen in characteris- tic proportions. radium.—chemists, especially those who are conversant with the manner in which function is correlated with structure in carbon compounds could not fail to be struck by these relation- ships. they have, therefore, long held the belief that ultimately the supposed elements would be found to be composites that were in some way structurally related. theimportant discovery of radium (g.v.), suddenly gave substance to this view, and the modern electronic conception of the structure of matter is no more nor less than its justification. at present, radium is the riddle of our chemical universe. to all appearance an element, in that it closely resembles the metal barium, it differs from all that were previously known, except thorium and uranium, in that it spontaneously undergoes decomposition, at a definite rate, giving rise to helium and another gas (radon), the which gas, in turn, again gives off helium and is ultimately converted into lead (see rapio-activity). strangely enough, we cannot intluence these changes by any of the means at our disposal. whatever lead may be, radium and the intermediate elements seem to be its helides. helium (g.v.) is suddenly become to the chemist one of the most interesting of known substances. tsotopes.—ballistics (q.v.) have played a great part in the further recent development of our knowledge. the molecules in gases are always in turbulent motion. first sir j. j. thomson, then f. w. aston, have developed methods of firing atomic molecules (molecules reduced to their ultimate degree of fineness) through a very narrow tube and directing their course of travel by electric 582 and magnetic controls, so that they are delivered at a photo- graphic plate at points determined by their mass and the electric charge they carry. from the photographs so obtained, it is possible to deduce the masses of the impinging particles (sce isorores). treating nitrogen and oxygen in this way, hits are scored in positions 14 and 16—-showing that the ordinary dia- tomic molecules of the gases are resolved into monatomic mole- cules. hydrogen hits are scored shghtly off position 1, in agree- ment with the conclusion that it is slightly heavier than unity. the strangely fractional atomic weight of chlorine, 35-36, has always puzzled chemists: some have even thought it to be a mixture. aston has shown that this is so. firing the molecules at his photographic plate, he has scored hits at two points, 35 and 37, the impression produced at 35 being about double as intense as that at 37, justifying the assumption that ordinary chlorine is a mixture in the proportion of 2:1 of two sets of molecules, one of mass 35, the other of mass 37. these two constituents of chlorine, apart from the difference in atomic mass, differ so little in chemical behaviour, that they pass as alike: they are like ‘identical’ twins born at slight intervals apart. such are termed isotopes. classification of elements.—chemists are still further indebted to physicists for the aid they have recently received from them in classifying the elements and “ fixing ” their possible number. when a slit of light falls upon a plate upon which fine lines have been ruled close together (a diffraction grating) the slit is spread out into a coloured band or spectrum. in like manner, when x-rays fall upon a crystal surface, striking the atomic centres, which may be regarded as forming lines corresponding to those on a grating, they are deflected to an extent which depends chemistry upon the atomic masses (see crystallography). when the a-ray spectra of the elements are arranged in the order of the atomic weights, one below the other, they form a stepped series. the staircase is seen to be complete, except in very few places— the number of steps indicated between hydrogen and uranium being 92; in the table below the elements are arranged in the order of their atomic weights, horizontally and vertically in great families. as in human families, there may be marked diversity of character within a family. electricity.—having thus sketched, in barest outline, the manner in which chemists have gradually developed their knowledge of the materials open to study and established an atomic theory of the constitution of matter, of which an exten- sion is foreshadowed in the electronic conception of atomic matter, we may pass on to consider the value of the several pieces on the chemist’s chessboard and the manner in which the game of chemistry is played in the laboratory and in nature. progress has not always been premeditated but has often been the outcome of some happy accident to a shrewd observer. such was the case when galvani (1779) noticed that a frog’s leg was caused to twitch when picces of two different metals touching at the one end were placed, some distance apart, upon the bared muscles; hence arose the discovery of what became known as the galvanic current. soon afterwards (1780), volta constructed his electric pile, consisting of alternate discs of copper and zinc separated by discs of paper moistened with a solution of salt. workers were thus provided with a means of producing an clec- tric current. good use was soon made of this, especially by sir humphry davy. his successor, faraday, was the first to show, though not until 1833, that the electricity of volta’s pile was genetic table of elements 1. iivdrogen 1-008 @) 2. he4 3. li6-94 4. beg 5. b 10-9 6. c12 7. n 14-01 8. o16 9. fig (7-6) (11, 10) oo e) o oo 10. ne 20-2 11s na-23 12. mg 24-32 13. al 27:1 14. si 28-3 is. p3104 16. s 32-06 17. cl 35-46 (20, 22) oo (24, 25, 26) (28, 29) ) oo (35, 37) 18. a 39-88 19. k 39:1 20. ca4o:07 21. sc 44:1 22. 11 48:1 23. v 51-06 24. cr 52 25. mn 54-93 (40, 36) (39, 41) 26. fe 55-85 27. co 58-97 28. ni 58-68 (58, 60) 29. cu 63°57. 30. zn 65-37 31. ga 699 32. ge 72°5 33. as 74:96 34. se 79:2 so. . 798 0 79, 81 36. kr. 82-92 37. rb 85-45 38. sr 87-83 39. ¥t 88-7 40. zr 90:6 41. nb 93:5 42. mo 96 ss. (78, 80, 82, 83, (85, 87) 84, 86) 44. ru ior:7 45. rh 102:9 46. pd 106-7 47. ag107-88 48. cd112-4 49. in 114-8 50. sn 118-7 51. sb120-2 52. ter27-5 53. i 126-92 : o 54. ne m30-2 55. cs 13281 56. iba 137-37 57. la 139 (129, 132, 131, ¢) 58. ce 140:25 134, 136) 59. pr 140-6 60. nd 144°3 61. ———— 62. sa 150-4 63. eu 152 64. gd 157°3 65. tb 159-2 66. dy 162°5 67. ho 163-5 68. er 167-7 69, tm 168-5 70. yb 173°5 71. lui7s5 72. tif 178-6 0 0=—6. 73. ta r81-5 74. w 184 75. —— 76. os 190-9 77. tr 193-1 78. pt 195-2 79. au1g7-2 80. iig 200-6 81. tl 204 82. pb 207-2 8&3. bi 208 84. polonium 85. ———— (6) 197 to 204 206, 208 (various radio {various radio (various radio (various radio . elements) elements) elements) elements) 86. nt 222 87. 88. ra 226 89. ac 226 90. th 232-15 91. 92. u 238-2 (th em 220 (th x 224 (ms th ii 228) — (warious radio ux 2 (u il 234) ac em 218) ac x 222) clements) (for latest isotope numbers see isotopes.) chemistry identical with that produced by friction or let loose in the thun- derstorm. the difference was only in concentration or potential. frictional electricity, though small in quantity, is of high po- tential—able to leap across considerable spaces—whilst that from the voltaic pile or galvanic battery (both terms were long in use together) is of low intensity but of any desired quantity. prior to faraday, in 1801, nicholson and carlisle had passed the electric discharge through water, obtaining hydrogen and oxygen; davy, in 1807-8, obtained the alkali and alkaline-earth metals by similar means. electrolysis —yfaraday, from 1834 onwards, systematically studied, in an exact manner, the effect of electric currents upon compound substances generally. some, relatively few, carried or conducted the current and, as a consequence, were decomposed. heestablished two classes of electric conductors—(1) metallic con- ductors, the metals generally (all elements), which carried the cur- rent more or less well, conductivity always diminishing as the tem- peraturerose;(2) electrolyticconductors,compoundswhichcarried the current but were decomposed as a consequence—conductivity increasing as the temperature rose. all such compounds be- longed to the class of ‘ salts,” including acids and alkalies, in thisclass. apparently, no compound acts asa metallic conductor. the term electrolysis was coined by faraday to express decom- position by an electric current; he termed the compound affected the electrolyte; electrolysis being effected by plunging two plat- inum plates attached to the two poles of an electric battery into the fused substance or a solution of the substance in water. he termed the plates electrodes, the one the kathode, the other the anode. the two substances into which the salt was immediately resolved were termed zons—travellers—one the kation, the other the anion. by no means are all salts by themselves electrolytes, in the liquid state. sodium chloride, silver chloride, lead chloride and tin dichloride are all easily electrolysed; beryllium chloride, stannic chloride, sncl,, mercuric chloride, hgchk, to mention only a few, are not, however. in fact, per-salts generally are non- conductors. there is reason to think that only metallic salts are conductors, and proof has yet to be given that these would be electrolytes, if free from all impurity. the liquid hydrides, apparently, are non-conductors. thus, the conductivity of water diminishes rapidly as it is purified and is ultimately so slight, that if the impossible were done and all impurity removed, we may well suppose that it would be a non-conductor. there is no other logical conclusion to be drawn from the facts. liquefied hydrogen chloride behaves similarly. yet if the two be mixed, solutions are obtained which conduct readily: the specific con- ductivity rising rapidly, as the chloride is diluted, to a high maximum, then falling but much less rapidly to nil when water is reached. it seems that two types of electrolyte must be dis- tinguished—(r) simple: certain fluid salts; (2) composite: solutions of salts in water (and a few other media). electrolysis is a very definite operation. the substance affect- ed is always split into two equivalent portions or radicles (ions). ifa current be passed through a serics of solutions, the radicles are separated in equivalent proportions, which are not necessarily atomic. thus sodium, silver and lead chlorides yield their radicles in the proportions cl na ag pb/2 35°46 23 108 103 —faraday recognised that a definite quantity of electricity was associated with the atom and that the unit quantity (the equiva- lent) carried the unit electric charge. much later, helmholtz insisted on the importance of the conception of atomic charge and johnston stoney termed it an electron. finally, sir j. j. thom- son gave precision to the idea, claiming that the electron is, as it were, a material particle of negative electricity, about 1/1800 of the mass of the hydrogen atom. none the less, it seems to be the most masterful unit with which we have to deal. to-day, it is supposed that the atoms consist of highly-condensed, positive- ly charged mass centres surrounded with electrons, in numbers depending upon the mass of the nucleus (see atom; electricity; electron; matter). 583 all such speculation is of infinite interest but at present it is outside the chemist’s ken; he must await the time when the physicist has developed the subject to the point at which it may be of constructive use to him, particularly in explaining dynamic peculiarities which thus far have met with no feasible inter- pretation. his own formulae are sufficiently vague and wooden, in their implication. the poor paraphrase, those who dabble in electrons would substitute, has no real meaning at present. in fact, the time is not yet ripe for the considered use of the electron in chemistry: the substitution of an artifice for a system of proved efficiency, by no means yet exhausted of value, is to be deprecated. at the present day we need more than ever to go back to the laboratory and work seriously and constructively at things we understand and dare speak of truthfully—without pretence of knowledge. nature of chemical change-—the electric current “ reverses ”’ chemical change but is itself produced by means of chemical interactions—in the voltaic cell. faraday was the first to recognise the inseparability of the two phenomena. no student of chemistry should fail to study his electro-chemical researches from this point of view. a cheap reprint is published in the everyman sertes. what is a voltaic cell? how does it function? volta’s pile consisted of discs of zinc and copper with an electrolyte (a solu- tion of salt) in between. this has served as the model of all developments of the “ cell,” which always consists of a metal used as anode, which can be associated with one radicle of the electrolyte, the kathode being an inert metal, usually platinum— or a conducting char (coal). tiree conductors, therefore, are thus coupled in a circuit: one of them, however, is composite and a conductor. this is the inevitable arrangement of an electrolytic couple or voltaic element. originally, common zinc was used but this is readily attacked by acid when “ uncoupled ” and so is used wastefully. gradually, it was discovered that the less impure the zinc, the less readily it was attacked when uncoupled: then it was found that if it were coated with mercury (amalga- mated) it was not attacked in open circuit. notwithstanding this definite statement made by faraday, and his insistence (in 1833) upon the essentially electrolytic character of the change when a metal, like zinc, is attacked by an acid, like sulphuric, practically to the present day, in the text- books generally, little or no heed is taken of his findings. hydro- gen is spoken of as prepared by dissolving zinc in sulphuric acid. hydrogen and oxygen are said to interact to form water, etc. etc., and bare equations are given in illustration. the conditions under which such changes take place are rarely, if ever, pointed out and made clear. during the past 50 years, however, a large amount of exact work has been done, particularly by h. b. baker, which entirely justifies faraday’s statements. it was early observed, by wanklyn and others, that carefully dried chlorine has little if any action on metals which are readily attacked by the undried gas. then h. b. dixon showed, that a mixture of carbonic oxide and oxygen could not be fired, if it were dry. h. b. baker extended the observations to charcoal and phos- phorus, showing that these did not burn in dry oxygen. on this jast occasion (1885), h. e. armstrong insisted that the condi- tions required by faraday’s generalisation must be fulfilled, if chemical action were to take place in such cases. taking the formation of water, as an illustration, he contended that oxygen and hydrogen could not interact, as neither was an electrolyte; further, that interaction would not be induced even by the presence of water, as this was not an electrolyte and did not form one with either oxygen or hydrogen: the presence of im- purity (a trace of acid or alkali) was essential to constitute the needed electrolyte. several years later, this forecast was verified by h. b. baker, and so many similar verifications of the view have been secured that it may now be regarded as an expression of the facts generally. apparent exceptions have been shown, one by one, to fall out, when proper precautions have been taken to secure the necessary freedom from dirt—defining dirt as mat- ter in the wrong place. 584 the equation of chemical change may be written generally a, + 66 + b, = ab + ab + €6 where €5 represents maybe a mere trace of the indispensable electrolytic detcrminant. catalysts —the term determinant should not be confused with that of catalyst (q.v.) which is of frequent occurrence in modern chemical literature. the latter term was first applied by berze- lius not only to the action of sulphuric acid in promoting the formation of ether from alcohol and of glucose from starch but also to the action of platinum black in promoting the oxidation of alcohol to acetic acid, as well as to the action of the enzyme (ferment) diastase in malt upon starch. these are not com- parable changes: the first two occur in solution, the second two at the surface of solids and, as the solid has a specific surface- effect in hastening the change, such actions may be treated apart. it is desirable, in fact, to confine the term catalyst to the solid agent which thus acts, not as mere determinant but in quickening a change already proceeding or which may proceed under the influence of a determinant, the change being one which could not occur in the absence of this latter. the equation of change, when a catalyst (x) is operative, may be written: az + 66x + be. = ab + ab + €dx. even when the necessary condition of impurity (the deter- minant) is secured, no metal can be caused to dissolve in an acid, unless st have a positive heat of dissolution—or, stated more sim- ply, unless the heat of formation of its oxide be in excess of that of hydrogen. thus copper is insoluble in acids generally. the approximate heat of formation of copper oxide being only 40,800 or 37,000 units, according as that of cuprous or of cupric oxide be taken, that of hydrogen being 68,000 (gramme degree) units— these being the quantities of heat liberated in the use of 16 grammes of oxygen at atmospheric temperature. if, as is con- tended here, water be concerned, at least in most chemical inter- changes, this is but a rational result. though insoluble alone, copper is easily dissolved in presence of oxygen—which acts as an adjuvant, throwing energy into the circuit—as shown in the following empirical equation :— cu + so; nr ee h, -+ oz = cuso, + be ae i + h.0.. the action of copper sulphate in the daniel cell and of nitric- nitrous acid in the grove cell is of the same kind: zn + soqq.. . h, + so, .. cu -+ cu = znso, + ae h.so, > + cucu. in a simple zinc-sulphuric acid-copper couple, the copper plate soon becomes “ polarised ’’ by the accumulation of hydrogen. this is prevented by the copper sulphate, as copper is displaced from the salt by the hydrogen and the electrode surface remains uniform; but such displacement involves the liberation of energy, so the compound cell has both a higher electromotive force than the simple cell and gives a steady current. substances which thus act as adjuvants are termed, generally, depolarisers. the importance of this limiting effect, imposed by the need of electrolysing water in a circuit of chemical change, has yet to be recognised. 3 , acid action.—wad simple considerations of this kind and the function of the depolariser been appreciated, the complex series of interactions observed on dissolving metals in more or less impure nitric acid—one of the most involved chapters in chemistry—would have been interpreted without difficulty. it would have been realised that the acid proper acts only in one way-—as a compound of the two ions, h and no;. it must be incapable of acting directly as a depolariser. the depolarising action of the impure acid is to be attributed, if not to nitrogen dioxide itself, to some nitrous compound which this forms with the acid. the various products, other than the nitrate, ob- tained in dissolving metals in the acid, are all reduction products, less or more remote, formed by the interaction of hydrogen dis- placed in the electrolytic current in which the nitrous compound acts as depolariser, the rapidity of delivery ofthe hydrogen determining the extent to which the reduction is carried. chemistry corrosion of metals —in recent years, there has been a vast amount of discussion over the corrosion of metals. in this case also, had the elementary principles of chemical interchange been grasped and taken into account, much of this would have been unnecessary and a more useful direction would have been given to the work. to take only the rusting of iron—this may clearly occur in two ways, either in a simple or in an aided circuit. in so far as the iron itself is concerned, it may be said, without hesitation, that it is acted upon only by acid and in one way: fe + 2hx = fex, + hp» (see rustitess steel). out in the open, carbonic acid is the effective agent; in towns this may be anything. if the liquid film in which the action takes place be free from oxygen or reducible substance, the negative element in the couple (carbide or other active impurity in the iron) is soon polarised and the action takes place irregularly and slowly. if, by the intervention of dissolved oxygen, the polarisation be pre- vented, action will not only be continued but accelerated, owing to the adjuvant effect exercised by the depolariser. such attack is corrosion but not rusting. rusting is due to the separation at the surface of the iron of oxide cither from the ferrous salt which is initially produced or from ferric salt formed from this ferrous salt: these salts are continually being hydrolysed as they are produced. so long as acid can penetrate through to the iron surface, the action must continue. the character of the deposit will clepend upon secondary changes, due, usually, to the inter- vention of oxygen as depolariser. water.—of all substances known to us not only the most active and useful but the most marvellous is water. without water, apparently, ‘‘ chemical change,” as we know it, could not occur—the world would not merely be lifeless but subject only to “mechanical” decay. the contrasts water affords, in its three states, is shown by no other compound—specially remark- able is the change that attends the passage from the liquid to the solid state, involving a sudden growth in volume of about one- tenth. some new “ planetary system ” may well be supposed to come into existence, owing perhaps to a great rearrangement of orbits. when this can be fully explained, in terms of electrons, chemists may well begin to take these seriously in their work— not before. ‘the life-history of water is a wonderful story. com- mencing with the two gases, hydrogen and oxygen, two of the least coercible that are known to us, on interaction (under the influence of a determinant and probably also of a catalyst), these afford the liquid water. much “ energy ” is set free in the process, ultimately as heat, the amount developed in the creation of the gramme-molecular proportion (18.016 grammes) being enough to raise the temperature of nearly 7oo grammes of water from 0° to 100° c. what meaning are we to attach to the word water, however? it should be reserved for and applied to the liquid alone, which undoubtedly is a complex. the fundamental unit molecule, represented by the symbol ohn, is best spoken of as hydrone. this is a gas under ordinary conditions. the formation of water from this gas may be pictured as a chemical process or interaction in no way distinguishable, in principle, from that involved in the primary interaction of the gases hydrogen and oxygen. aitken’s expcriments are held to have proved that the condensation of “aqueous vapour ” and the formation of drops of (liquid) water in the atmosphere—of cloud—only takes place around a solid nucleus—a catalyst, in fact. it is more than probable, that it will eventually be found and admitted that a determinant—a trace of some ‘salt ’—is also necessary. such impurity is always present, in the form of carbonic acid, nitrous and nitric acids, if not of sulphurous or sulphuric acid, an ammonium salt or sea salt. the nature of the interaction, the composition of the product, is undetermined. probably, water is a mixture of vari- ous liquid components, of folyhydrones (h.o),, (11,o)y,, etc., saturated with the gas hydrone oii., the proportions of the constituents depending upon the temperature. even above 4°, the point of maximum density, the liquid must be saturated with ice-molecules: the complexity of these is also undetermined— maybe the hydrone unit simulates the carbon unit and preferen- tially combines in sixes. it is a matter of interest that ‘‘ ices ” chemistry of greater density than ordinary ice may be obtained by sub- jecting ice cooled to various temperatures to great pressure. all suggestions hitherto advanced as to the composition of “ water ” molecules, under various conditions, may be regarded as purely speculative. water is a specially active solvent of compounds—after its own heart: of compounds of oxygen and of the halogens, in a lesser degree of nitrides (compounds of the ammonia type), not at all of “neutral ’’ compounds of carbon (the hydrocarbons). dissolution—whatever the solvent—presumably, is a chemical process, in the main: not a mere intrusion of the dissolved mole- cules among those of the solvent but the consequences of some degree of ‘“‘ affinity ’’ between the contending molecules. the process cannot, therefore, well be considered without reference to the affinities of molecules and of their constituent atoms. affinity and valency—the gas hydrogen, as we know it, is an almost neutral material. it is condensed to a liquid only under high pressure, at a low temperature; the liquid boils at —253°. the molecules of hydrogen, therefore, have but little affinity for each other. the molecule is diatomic, being represented by the formula h,. as the two atoms are firmly held together in the molecule, they must have considerable affinity for each other and nearly satisfy one another: the molecule has but a slight, ob- vious, residual affinity. the same may be said of gaseous oxygen. being far heavier than those of hydrogen, the molecules are, in a measure, less swift in movement and more easily ‘‘ caught ” by other molecules. oxygen is definitely more active and displays a high degree of residual affinity. moreover, we must picture atomic oxygen, like atomic hydrogen, as gifted with intense affinity—with an almost indiscriminating affinity, as excepting the argonides and fluorine, it forms compounds with all the ele- ments, most of which are of a relatively high order of stability. it is a far more companionable element than hydrogen. bring hydrogen and oxygen together, in presence of the necessary negotiators of change, allow them to interact in the sense of the equation, 2h, + dx + os = 2h20 + €bx they give rise to hydrone and eventually to water. these prod- ucts differ in an astounding way from their generators. the molecule of hydrone has little more than half the mass of that of oxygen, yet-—-given proper conditions—it condenses, with the greatest ease, to water. not only so, the amount of energy set free in the interactions of the molecules of hydrone, x oh: = (oi1,)x, is about one-tenth of that liberated in the original gaseous interaction. the molecules of hydrone are thus shown to be possessed in a far higher degree of residual affinity than is even oxygen. hydrone, indeed, may be said to be a really active form of oxygen-stuff—far more so than oxygen itself. ilence water is so good a solvent: at least, there are molecules in the liquid mass which are very active, chemically speaking. water, we shall see, must be regarded as a complex mixture, in which are present molecules of varying degrees of complexity: j1.0, (h:0),, (11:0),, etc., in proportions which depend upon tem- perature. hydrogen and chlorine similar considerations apply to hy- drogen and chlorine and to hydrogen chloride, the product of their interaction—under appropriate conditions. although chlorine is much more easily condensed than is oxygen, and therefore is to be credited with an even greater store of residual affinity than is oxygen, strange to say, hydrogen chlorice, though a more massive molecule than hydrone, has little attrac- tion for itself, being far less easily liquefied than is hydrone; moreover, the liquid is a poor solvent compared with water. nevertheless, hydrone and hydrogen chloride attract each other irresistibly—the chloride is very soluble in water. we have to consider what the nature of the interaction may be in this and in other cases of dissolution in water. azote.—azote is more extreme in its behaviour than is even hydrogen. the molecule n; is all but inert under ordinary con- ditions, yet we have every reason to believe that its component, atomic nitrogen, is gifted with intense aflinity. whereas hydro- 585 gen and chlorine, respectively hydrogen and oxygen, interact readily, when merely brought together in presence of the neces- sary determinant and the mixture is sparked, azote and hydrogen interact only under high pressure, at a fairly elevated tempera- ture and in presence of special catalysts. the interaction, more- over, is very partial: in fact, the product, ammonia, is formed reversibly: ne + 3h: 2nhs3, interaction taking place far more readily backwards than forwards. ammonia.—ammonia, like hydrogen chloride, has little affinity for itself, though more easily liquefied than the latter; the liquid has special solvent properties of a most interesting character. the gas is readily dissolved by water but is easily ex- pelled from the solution. most characteristic of ammonia is its behaviour with hydrogen chloride: the two interact, when properly impure, on admixture, forming the white crystalline solid, ammonium chloride tic] + «5 + nh; = nh,ci + «6 a salt which bears the closest possible resemblance to common salt. | carbon.—lastly, we have to consider the most attractive to the fair sex of all elementary materials—carbon. we ought to confine this term to the ideal represented by the symbol c— which we cannot directly handle. we only know it in its com- pound polyatomic form, as diamond: a compound of extraordi- nary interest. if the chemist were properly mindful of the wondrous power of carbon as the foundation stone of the organic world, he would wear the biggest diamond procurable— as ‘“ mark of the beast.” it is customary, in the text-books, to speak of forms of carbon other than the diamond—to wit, graphite and the charcoal-carbons. no proof has yet been given that these are carbon—much may be said in favour of the view that they are but highly condensed hydrocarbons. carbon and hydrogen interact only under special conditions— at the high temperature of the electric arc—the product being the gas acctylene, c2ii1,. the simplest ‘‘ hydrocarbon ”’ is methane, cl, known generally as miners’ fire damp (dam}f, vapour) and as marsh gas, as it is often met with as the product of the natural decay, under the influence of special micro- organisms, of cellulosic materials. methane is an inert material, in so far that the four affinities of the carbon atom appear to be satisfied by the four hydrogen atoms and, reciprocally, the affinities of the hydrogen atoms by those of the carbon atom: it is one of the least coercible of gases. derivatives are only to be obtained from it by displacing one or more of the four hydrogen atoms by some equivalent radicle or radicles. the four hydrides considered, taken in conjunction with hydrogen, form a remarkable series:-— h, hicl h20— nh; cg: three of these are eminently active compounds, obviously possessed of residual affinity, whilst the fourth, methane, appears to be individually inert: in this compound, carbon and hydro- gen, apparently, are mutually satisfied. what is to be the con- clusion from such evidence? is it to be, as appears from the behaviour of hydrogen itself and of methane, that the hydrogen atom is a single-minded individual, able to grasp at most a single other atom: that the unsaturated character of the hydrides of chlorine, oxygen and nitrogen is a consequence of the inability of one, two and three atoms of hydrogen respectively to satisfy the desires of these elements? this, indeed, has long been the opinion of chemists generally. hydrogen is considered to be a consistently monadic or univalent element and those with which it associates are often elements of variable valency, the desires of which it cannot fully satisfy. in recent years, the reputation of hydrogen as a simpleton has been impugned—yet not seriously: on careful consideration of the statements made, in the light of the facts, there seems to be little reason as yet to regard them as of more than imaginative value. | the hydrides of fluorine, bromine and iodine—all elements of the chlorine family—are in most respects scarcely to be | distinguished from hydrogen chloride. | _— ——f 586 water may be said to be entirely peculiar in that the “ re- straining ” effect of hydrogen upon the oxygen atom, in the unit molecule ohkg, is so slight. the hydride of sulphur—the element akin to oxygen and next below it in the oxygen family—al- though similar to hydrone in composition, hydrogen sulphide, has none of the properties of the oxide. it is gaseous and not easily liquefied and the liquid is a poor solvent. strangely enough, however, if the hydrogen in the two hydrides be dis- placed by the hydrocarbon radicle (c.h;), compounds are ob-~ tained in which the properties are, in a measure, reversed. ether, (cshs).0, has little tendency to associate with other compounds. the diethyl sulphide (c.h;)}.s, however, is reaclily combined with the iodide c.h;i, forming the iodide s(c2i;)3i, a beautifully crystalline substance in which sulphur appears to be definitely quadrivalent—like carbon in methane. in short, affinity, the valency of a radicle, like human affection, is clearly a relative rather than an absolute function: valency is a variable, not a constant, at least in many cases. perhaps the only element of constant valency is hydrogen—but this is singular in many ways. this assumption is, at least, a desirable one to make, so long as it cannot be disproved: im fact, it 1s that upon which our entire system of structural formulae in organic chemistry has been builf up. the consistency of that system is so marvellous, that our confidence in it will not easily be disturbed. accepting the conclusion that oxygen has more or less residual affinity when associated with two hydrogen atoms, as it is in hydrone, what interpretation is to be placed upon the process of dissolution in water? what is water, as compared with hydrone? by what act do two diverse liquids give rise, upon admixture, to a solution conducting more or less well, which apart are without the power of acting as electrolytic conductors? when hydrogen chloride is dissolved in water, a highly conduct- inz solution is obtained; when ammonia is similarly dissolved, the conductivity of the solution is low, at best. what is the differ- ence? when hydrogen chloride and ammonia gases are mixed in equal volumes, they at once interact in the sense of the equation nh3 + 66 + hcl = nh,ci + 66. the product is a crystalline solid, a definite compound, the salt ammonium chloride, which most closely resembles common salt, nacl. we cannot well do otherwise than assume that whilst only tervalent to hydrogen, the nitrogen in ammonia becomes excited to a higher valency when a fourth positive hydrogen atom is offered to it together with a fifth negative (chlorine) atom. the two molecules, ammonia and hydrogen chloride, do not merely combine but that of the chloride, apparently, ¢s divided and dis- tributed upon the ammonia molecule, the nitrogen functioning as a quinquevalent radicle. if the same simple assumption be made, the interaction of hydrogen chloride with hydrone, in water, may be represented in the following manner of anes = o of et= oc as, however, oxygen and chlorine are observed to act in a similar and equivalent manner, interaction should also take place as expressed in the equation h o +clh = nat if oh the interaction of ammonia and hydrone molecules, in like manner, should give rise to ee of two kinds, viz., h h ni and “sot . ho h nh in such compounds, ae by the exercise of secondary affinity, the xegative radicle in each complex is clearly less firmly held than in the simpler compounds from which it was formed and, therefore, should be more easily separated, we may sup- pose: the ‘‘ residual ” affinity of the radicle must be greater than chemistry it was in the simple molecules. for example, in the complexes formed from hydrogen chloride and hydrane, ii;0:cl and h.cl]-oh the chlorine radicle in the one, the hydroxyl in the other, is less firmly held than it was in the original simpler molecule. the atoms are all less firmly knit together in the complexes. their condition is, perhaps, that sometimes spoken of when such mole- cules are said to be “ electrically charged.” complexes such as are here contemplated are also formed, it is to be supposed, from the fundamental units which constitute the gaseous substance. on liquefaction, these undoubtedly become associated in various ways. thus, liquefied hydrogen chloride may well be supposed to consist of complexes such as hh h h h cl cl cl c1—cl hcy na noa and ok | h h ccl—cl h oh saturated with the simplex hcl. it is impossible to say in what proportions these are present: possibly the one form is dominant. water, we may aver, is equally a mixture of the fundamental unit, hydrone, oh, w ith complexes such as he ho ha, hw, he o qo oh—o h0” so” soz” non and 10 don he h, carbon compounds of these types are well known as stabie structures, such as th us th ti te cc—c hc” arr a7 are and h.c < ys h, h, c=c h, hy, there is general agreement among chemists and physicists that the carbon compounds are thus constituted. the angles at which the carbon atoms meet in the diamond, the distance apart of the atomic centres (of the carbon atoms), have been’ exactly deter- mined, in recent times, by means of x-rays. the carbon atoms meet at 109°28’, the tetrahedral angle; the centres are little more than an angstrem unit (one hundred-millionth of a milli- metre) apart. there is no reason why we should not see, with the mind's eye, in the liquefied hydrides of chlorine, oxygen and nitrogen, a structure such as we have seen, largely with the actual eye, in hydrides of carbon. common water will convey or conduct an electric current— electrolytically. the more it be purified, the less readily it con- veys the current. jf 1s logical to assume, that water free from every contaminaiton, would be a non-conductor. such water is an ideal. water cannot be dealt with without a containing vessel: whatever be the nature of the vessel in which it be received and stored, the surface will be more or less contaminated and more or less subject to attack. the “ best water” that has been made, has been made in glass and measured in glass—glass we know is attacked by water. in testing electrically platinum electrodes are used—platinum, we know, is an absorptive material and pure platinum is inconceivable as a reality. a pure substance is the thing itseli—there may be degrees of impurity but not of purity. we are so accustomed to an impure world, that it is difficult to rise into the empyrean of ideal purity: physicists have long been noted for their lack of the sense of cleanliness; chemical sanita- tion is not yet generally at the height at which it should be— and gullibility, of the order pictured by carlyle, still plays a large part in our society. naughty and undisciplined as we may scem to be, the general tendency is to obey and follow the pretending leader. electrolytic action~-to explain the observation that any electromotive force, however small, would produce electrolysis in a solution, causing the ions of the solute, say the hydrogen chemistry (h) and chlorine (cl) of hydrogen chloride (hci) dissolved in water, to pass to opposite electrades and there unite and appear as hydrogen (h{.) and chlorine (cl.), clausius long ago “ pre- tended ” that some few of the molecules of the chloride “ banged themselves to pieces ’—so that no work had to be done by the electric current in separating the ions: it only was necessary to give them direction and set the one to wander to the negative, the other to the positive electrode. this electrical test, however, is one of infinite delicacy—no thought has been given fo the fact that the recluction of the “ impurity ” at an electrode surface to an extent beyond or even equal to that of the delicacy of the electrical test is a practical impossibility. chemists have been led to base their faith, the entire theory of chemical change, upon the observations of two german physicists working in the dim and distant past of 40 years ago—both honourable men but both physicists and mathematicians, not practised chemists alive to the need of the most excessive sanitary precautions, if a chemical clean bill of health were to be secured. helmholtz is supposed to have electrolysed water by means of non-polarised electrodes. in fact, he used two platinum plates and a third plate of palladium charged with hydrogen: his solution was, there- fore, necessarily charged with hydrogen and one or other of his plates was “ hydrogen polarised.” arrhenius, in 1885, extended the clausius hypothesis but dropped his mechanical explanation. to account for the de- velopment and increase of electrical conductivity on dissolving a “salt? in water, to an extent varying with the nature and the proportion of salt used, he assumed that the molecules of the dissolved salt just fell to pieces into separate electrically charged tons. why or wherefore they did so, where the energy to break them up came from, was never explained. as a matter of fact, what has to be explained is the appearance of electrical conductivity and also of chemical activity, on bring- ing together two substances which, if logic have any meaning, by themselves are inert. logic seems to indicate some interaction as the only possible cause of the change. the electrolytic dis- sociation school did, after a time, attribute the change to the high ‘‘ specific inductive capacity ” of the solvent—whatever that may mean. directly the solvent is called in, the explanation becomes chemical, however, not merely mechanical nor based upon a display of mere wilfulness. “‘ we will dissociate, nothing shall prevent us,’’ was the war cry of the molecules, according to arrhenius, the chemist had more belief in their moral character and that they would observe the marriage tie. what arrhenius really did—and the service was a great one at the time—was to lay great stress upon the existence of an ac- tive as distinguished from a passive part, in a chemically active medium, by correlating the electrical conductivity developed in a solvent by the addition of a “ salt ” with the chemical activity of the dissolved substance—assuming the dissolved substance (in the form of its ions) to be the sole active agent. he also de- veloped kohlrausch’s conception of molecular conductivity, as distinct from that of specific activity (of the solution as a whole), by referring the conductivity to the ions of the solute alone and correlating this, to some extent, with chemical activity. the generalisation came at a time when much attention was being paid to the determination of molecular weights of dissolved substances. raoult especially had shown that equimolecular proportions of many substances produced the same effect upon the properties of a solvent: for example in raising the boiling point; moreover, that, within limits, the effect was proportional to the concentration, af low concentrations. van’t hoff also had advanced a kinetic explanation of the phenomena of so-called osmotic pressure—the pressure developed within a cell, contain- ing a solution, by water passing through the lining membrane without the solute passing out. | osmotic pressure-——the pressure developed within a cell, by the entry of water (as shown by the rise of liquid in a gauge tube attached to the cell) into dilute solutions, appears to be the same as would be developed by the entry of a gas, in equivalent amount, into a cell already filled with the gas, at a known pressure, through a wall permeable only by the entering gas. for 587 example, when a cell of palladium (which is permeable by hydro- gen and not by nitrogen) filled with nitrogen at atmospheric pressure, is surrounded with hydrogen at atmospheric pressure, the hydrogen passes through until equilibrium is reached—when the hydrogen pressure is the same within and without the vessel: at this stage, the molecules of hydrogen are travelling at equal rates and in equal numbers both ways. the pressure within the vessel is thus raised to two atmospheres—by the addition of the atmosphere of ‘ pressure” due to the hydrogen. in the same way, when a dilute solution, say of x grammes of sugar in 22°3 litres of water, filling a finely porous cell provided with a gauge tube, is plunged into water, the liquid rises in the gauge tube ; oe ; until the pressure is ae of an atmosphere, 342 being the relative weight of the molecule of sugar. the late prof. e. f. fitzgerald, a distinguished physicist of unusual breadth of outlook, speaking of this phenomenon, says: — it is a most remarkable thing that osmotic pressure should be even roughly the same as what would be produced by the molecules of the body in solution if in the gaseous state but to imply that the dynamical theory of the two is at all the same or that the dynamical theory of a gas is in any sense an explanation of the law of osmotic pressures is not at all in accordance with what is generally meant by the word ‘‘explanation.”” this so-called explanation is not a dynam- ical explanation at all, it is only a very far-fetched dynamical analogy. these osmotic pressures are much more closely connected with laplace’s internal pressure in a liquid, which is essentially de- pendent on the forces between the molecules than with the pressure of a gas, which is essentially almost independent of the forces be- tween the molecules. there must be some dynamical reason why the solvent gets through the membrane while the body in solution does not. it must be due to capillary forces between the solid and the molecules of the solvent (helmholtz memorial lecture, chent, soe. jour., 1806). an understanding of osmotic phenomena is a matter of great importance, because of the part they play in the exchanges be- tween the cells which constitute living structures: the cell walls acting as discriminating septa. it should be noted that solutions in water have a lower vapour pressure and therefore a higher boiling point, also a lower freez- ing point than has water. this is true of solutions generally, whatever the solvent. in fact, all the properties of a solvent are modified by the presence of dissolved matter, whatever its nature may be, the alteration being proportional to the amount dis- solved—so long as the solution remains dilute. the striking contribution made by arrhenius in discussing van’t hoff’s gencralisation was in associating the superior, if not abnormal, eflect of electrolytes upon the solvent with the increase in molecular electrolytic conductivity of dissolved salts upon dilution. whereas non-electrolytes produce the unit osmotic effect, molecular proportions producing the same effect, elec- trolytes have more than unit effect and as the solution is diluted the effect increases, until, in the case of binary compounds such as hydrogen chloride, hc], for example, the molecular effect 1s practically doubled—as if the radicles h and cl were acting independently. arrhenius made the assumption that they were, but that the water remained unchanged. it is impossible to grant such an assumption. no valid reason has ever been given which will account for the separation, which is one involving a great ab- sorption of energy. actually, a not inconsiderable amount otf heat is evolved when hydrogen chloride is dissolved in water, part of which, of course, is due to the liquefaction of the gas. again, the assumption is one that involves a sharp distinction being drawn between hydrogen chloride and hydrone—speaking chemically, this is impossible, what is generally true of the one being true of the other. the nature of the change which it is conceivable takes place when hydrogen chloride and hydrone interact has already been pictured. in view of the known behaviour of hydrogen chloride towards ammonia, the chemist is in a position to assert that hydrogen chloride and hydrone must be able to interact and do interact in a similar manner. he can produce and exhibit in a crystalline form a compound formed from methylic oxide, (ch3)-0—the analogue of hydrone—and hydrogen chloride. 588 the question then arises—how are the alterations in the properties of water and of solvents generally induced by the presence of a substance in solution to be explained—how, in particular, is the peculiar and enhanced effect of (potential) electrolytes as compared with non-electrolytes to be pictured. the first assumption that may be made is—that, in all cases, the primary, chemically active unit is the simple molecule, hydrone, ohp, in the case of water. it will easily be granted that water is saturated with hydrone, the proportion varying with the tem- perature. asa matter of fact, the vapour pressure of an aqueous solution is lower than that of water. one effect of the solute molecules is, therefore, to capture and restrain a certain propor- tion of the hydrone molecules. it may be urged that as soon as hydrone molecules are withdrawn, others should come forward— produced by the breaking down of polyhydrones—to take their place and restore the equilibrium. the facis negative this as- sumption: the dissolved substance exercises an abiding influence. it is almost necessary to assume that the residue of the solvent is modified: that the complexes present along with the simple, fundamental molecule exist in a different proportion: that inas- much as the freezing point is lowered, the crystallisable form is diminished in amount. water near to its freezing point must be saturated with “ ice-molecules ” whatever the complexity of these may be. when a substance is dissolved in water, the hydrone solute complexes which are formed—whatever their nature—doubtiess exercise a disturbing influence upon the rest of the liquid and the equilibrium is perhaps altered in such a wav that fewer “‘ ice-molecules ” are present. as to the peculiar influence of electrolytes—we know that the departure from the “ normal” behaviour of non-electrolytes varies with the compound dissolved and the strength of the solution, the specific molecular effect being always greater the more dilute the solution. let it be assumed that hydrone and the solute, ab, interact in the following manner ar + on ar " ab ) 90 = ab non h +— ‘s ab + oh, = h,0% fach of these products will be an active unit—one that is more active than the molecule from which it is derived—than hydrone on the one hand, than the salt molecule on the other. the rela- tive proportions in which the two are formed will vary with the concentration. in concentrated solutions, however, a large proportion of the salt molecules will not form active complexes _ but, tt may be supposed, will be associated in grouped or closed systems, @.g., : 1g. tg ci ee ab + joh, = ae | oo il, te which are non-valent and only possessed of slight residual affinity. non-electrolytes may be regarded as differing from electrolytes in that they are not clivisible against hydrone, interactions taking place only in one way +- —+ sl xy + oh, s xve oh to explain the enhanced effect of potential electrolytes and the increase of the effect as the solution is more and more diluted is more difficult. as these are effects of dilution, they are clearly due in some way to the action of the water. the solution of the problem suggested by h. e. armstrong (rey. sec. proc. 1923, vol. a103, p. 610) is, that when the “ couple ” formed of the two systems h rs eae ; hoc and hydrone (oh;) is resolved, it may and h b , chemistry h ——a more active unit even oh than hydrone itself. further, that as dilution proceeds, ab is more and more completely resolved against hydrone and con- does give rise to hydronol, hoc . a verted into hoc . when this action is complete, ab has br exercised its maximum effect. hydronol, however, being pro- duced concurrently, is ultimately present in an amount equivalent a to that in which the system hoc is formed. finally, two b active systems are present: if the action be complete, the com- bined effect they produce is twice the unit effect. when a solution is placed in contact with water, separated by a diaphragm through which only the water can pass, hydrone is attracted into the solution, molecule for molecule of the active systems present. the so-called osmotic pressure within the cell may be conceived of as due to the directed oscillatory impacts of the hydrone molecules paired with the active systems. in a sufficiently dilute solution, ultimately, two osmotically active, reciprocal molecules would be produced, at the expense of each single molecule of the salt: in other words, the single molecule of the potential electrolyte, hydrogen chloride, would apparently have double the effect of a single molecule of a non- electrolyte. assuming that electrolysis involves the interaction of two diverse ‘ distributed ” systems, under the influence of an electro- motive force, the (molecular) conductivity of the dissolved chlo- ride would also be at its maximum in the fully diluted liquid. solutions.—the activities operative within solutions are too little considered. they are best realised by studying the inter- actions of soluble salts. when, for example, potassium chloride and magnesium sulphate, mgso4-7h.o, are dissolved in equivalent proportions and the solution is sufficiently concentrated, a large amount of the double sulphate mgso,-k:so4-6h.o, gradually crystallises out. it follows that much of the chloride is converted into sulphate and of the sulphate into chloride, in fact, mag- nesium chloride is ultimately obtained from the liquid. often, in such cases, a number of double salts and of salts with varying amounts of water of crystallisation are produced, the product varying with the concentration and relative proportions of the matcrials present. the presence of the variety of salts met with in natural salt deposits, such as those in alsace and hanover, is thus accounted for. finally, it may be urged that extreme caution is required in dealing with the problems of solution, because of the fact that the molecules are crowded together. whatever seeming analogies their behaviour may present with that of the gaseous state, the effects cannot be really gaseous effects—as intermolecular affinities come into play which are practically excluded in the gas. the conclusions deduced by studying solutions made by dis- solving substances all to the same volume—a method in no way comparable with that involved in dealing with equal volumes of gases—are obviously not comparable, as the molecular propor- tions in which solute and solvent are present will vary more or less, according to the nature of the dissolved substance. most of the peculiarities to which attention has been directed are traceable to this illogical practice. at most, very dilute solutions prepared in this manner will afford comparable results. on the other hand, if the molecular proportions of solvent and solute be kept constant, there is always the difficulty that the ultimate volumes vary—that the volume occupied within the solvent by the solute is subject to variation. in fine, it would seem to be impossibie to make any strict comparison of solutions—the con- clusions must always be open to many corrections. electrolysis of water-—the production of hydrone by the interaction of hydrogen and oxygen has already been discussed. the inverse change must be subject to similar conditions. water itself and by itself cannot be electrolysed—ex hypothesi, it has chemistry no eonducting power. to speak of the production of hydrogen and oxygen by electrolysis, as if the process were simple and direct, is as wrong as to speak of the production of water itself from oxygen and hydrogen: the electrode face must be the seat of a whole series of changes. without considering the nature of the internal process (within the liquid), it may be assumed that the eomplex oe (formed from the acid hx) at the one oh electrode surface is initially converted into a perhydrol + of). h such compounds are well recognised products of electrolysis. at times, they undergo hydrolysis and perhydrone ho-oh is formed, but this, apparently, is never an initial product. at high concentrations and particularly at high current densities, the attack by oil becomes more and more concen- trated upon the molecule and probably higher perhydrols are formed, which break up at the electrode surface into oxygen or ozone—whether directly or owing to hydrolysis or perhydrolysis. actdity: apparent and fe ffective-—the term acid has long been a bone of contention among chemists and there is great need of a clear understanding on the subject. a latin term, the equivalent of the teutonic sour, it appeals to the ear and is familiar because of the occurrence of acids in foodstuffs—in vinegar, fruit, etc. the opposite of an acid—an alkali or base—in the sense that it will neutralise the acid and destroy its sourness to the palate— is unfamiliar, as such substances are not in ordinary use, at least in connection with food. when acid and ‘ base” interact, a salt is formed. the base, however, is no more the base of the salt than is the acid: it happens to have been so-called, only because “acid ”’ was already appropriated and had a distinct, identifiable meaning, ‘‘ alkali’’ has no etymological significance in itself and the conventional use of base is misleading when transferred to chemical practice. | acids were known long before the isolation of the vital prin- ciple of air. when this was isolated, lavoisier gave it the name oxygen, because the oxides formed on burning common com- bustibles, such as carbon, sulphur and phosphorus, were “acid.” the oxides of the non-metallic elements then became known as acids. ‘to the present day, the public speak of the acidic oxide of carbon as carbonic acid, 2 far better name for general use than that of the chemist, carbon dioxide, which by a silly and most reprehensible practice is now often converted into see-oh-too (co.), especially in biological circles. formulae should never be used as spoken words. lavoisier supposed that acids generally contained oxygen and, on this account, being a constituent of muriatic acid, chlorine was supposed to be an oxygen compound. when this was disproved by davy and “ spirit of salt ” was shown to consist simply of hydrogen and chlorine, the swing of the pendulum set in and acids were defined to be compounds of hydrogen (hydrogen salts) in which the hydrogen could be dis- placed by metal, if not directly, through the agency of a metallic oxide or base. the name sulphuric acid was then transferred from the oxide so; to the hydrate, so3;+oh2=i1.s0g, oil of vitriol or vitriolic acid, as it was long called. vifty years or so ago, there were two contending schools—one calling the oxide the acid and the hydrate either simply monohydrate (a name long used in commerce) or hydric sulphate. a salt was said to be formed by the union of acid and base and, in hydric sulphate, hydrone was supposed to take the place of the base soda in sodic sulphate: the acid, in fact, was regarded as a hydrogen salt. the other school regarded a salt as derived from its acid by the displacement of hydrogen and the hydrogen as itself present in the form of hydroxyl (oth). the halhydrides were again treated as peculiar. the basicity, we may say equally well the acidity, of an acid varies with the number of displaceable hydro- gen atoms. phosphoric acid h3po, has long been supposed to be an acid in which the three atoms of hydrogen are of different h it hx + 2(oh) = xc ou 0-0 a a pk a a een rr value but sulphuric acid has almost always been formulated as if the two hydrogen atoms were alike in function. it has been customary to represent the latter acid as symmetrically con- oh stituted (so) when the matter is studied historically, oh | it is clear that this view is largely an academic conclusion. no significant evidence of structure can be adduced in proof of such a formula and we must admit that we do not exactly know how the acid is constituted—simple as it is. acidity—the issue is complicated by the fact that “ acids ”’ vary greatly in strength—some are “strong ”’; the majority are weak, defining apparent acidity as the equivalent proportion of “ acid ” present in a solution, which is measured by determining the amount of standardised alkali required to neutralise the liquid, the effective acidity is measured by using the acid as a hydrolytic agent, for example, in effecting the resolution of cane sugar into glucose and fructose:— , cpl eor; + ohs = 2c 6} oe. the activity of an acid such as acetic contrasted with that of an equivalent amount of chlorhydric or nitric, is very slight—it has not one-two hundredth of the strength of these strong acids as a hydrolytic agent. there is very little, if any, doubt that the explanation of this fact is, that but little of the acetic “ acid ”’ becomes real and active. on the other hand, almost the whole of the dissolved hydrogen chloride in muriatic acid seems to be in the active state—as the electrolytic conductivity, referred to the molecular proportion of hydrogen chloride present, is relatively little changed and increased by high dilution. nearly go% of the chloride appears to be present as the active acid even at low dilutions. instead of representing real or effective acidity as a fraction of the apparent acidity, thus avoiding the introduction of any hy- pothetical interpretation of the facts, an unfortunate practice has grown up of representing real acidity in terms of “‘ hydrogen- ion-concentrations.”’ nay, worse, the hydrolytic effect has been represented as due to the hydrogen ion and not to the ions of the acid acting in conjunction. terms are thus used which only the elect can understand—which is undesirable in all interests. at the moment, the term acid has no clearly defined meaning. much light is thrown upon the nature of multiacidic (multi- basic) acids by the study of their action as hydrolytic agents. especially is this true of sulphuric acid. this acid readily acts upon a variety of hydrocarbons and other compounds, forming sulphonic acids, e.g., cehe + h.so, a c.hs-so,h + ohg. the sulphonic acids are strong unibasic acids. it is usually said that they are formed simply by the displacement of one of the two hydroxyl groups (oh) in sulphuric acid by a hydrocar- bon or similar radicle. if so and the two (oh) groups be of equal value, the sulphonic acids, it might reasonably be supposed, should have about half the effective strength of sulphuric acid. as a matter of fact, tested by cane sugar, they have little less than go% of its strength. hence, it would seem probable, that sulphuric acid is in reality uniacid (unibasic) but has a slight residual acidity. the argument may be extended to all multi- acid inorganic acids. these seem to be comparable with lactic acid, ch;-ch(oh)-cooh, which from early times has ranked as part alcohol, part acid—as essentially uniacidic. the argu- ment is of consequence as pointing to some dissymmetry in-the structure of sulphuric, carbonic and other multiacidic acids. (compare roy. soc. proc. 1914, vol. ago, p. 73.) function as determined by structure —llaving thus considereda casein which function and structure are clearly in close connection, attention may now be directed to carbon compounds, which afford a vast mass of evidence of the absolute correlation of function with structure. the structural basis of chemistry is very simple—one of astound- ing simplicity, in fact. it isexpressed in the fixed series: hci, h.o, h3n, wic. taking the hydrogen atom as unit, the atom-fixing power or valency of the four elements indicated is one, two, 590 three, four-fold. chlorine and its analogues are monads, oxygen and its analogues dyads, nitrogen and its analogues triads, carbon and its analogues tetrads. all other elements (excepting the inert) fall into one or other of the four classes. the facts of chem- istry generally show that hydrogen is consistently a monad. the facts also show that generally carbon does not exceed the tetradic power of which ch, is witness. the other elements and their analogues are not so fixed in their affections. thus nitrogen, in the ammonium compounds, such as ammonium chloride nic, carries two additional units, five in all. oxygen and chlorine also may carry two additional units but their hold upon these is never so firm as is that of nitrogen. the problem of varying valency (atom-fixing power) has given rise to much discussion, over a long period of years; it is in no way ended. at one time, the view was held that in ammonium chloride, the two mole- cules h;n and hcl, were still existent, as radicles; such com- pounds were in consequence termed “ molecular.” phosphorus pentachloride, pcls, in like manner, was thought to be a com- pound of the chloride pc]; with a molecule of chlorine cl. of late years, the alternative view has prevailed, that the two molecules interact and do not merely “‘ associate,” so that the units are distributed and arranged about a central atom. chemistry, however, is an art as much as a science and the chemist is full of feeling which cannot be quantified. he is sat- isfied that, in some way, there is a difference which he is in no way yet able to define between the two orders of compounds. fancy pictures have been drawn of late, in terms of the electronic hypothesis, to represent the two kinds—but these are but para- phrase and as they carry us no further are premature. at most, we know, from the behaviour on electrolysis, that the various atoms carry atomic electric charges (electrons) corresponding to the primary valency—the hydrogen atom one, oxygen two, nitrogen three. the evidence thus far seems to be against the view that the atomic charges may be varied. what then is to be our explanation of secondary valency and still further of the residual affinity which is manifest when secondary affinities are engaged! no compounds, not even the inert gases, helium, etc., nor hydrogen, methane, etc., are entirely without attractive power or affinity. if they were, they would not be liquefiable. all dis- play a certain amount of residual affinity: in other words, what- ever the nature of primary and also of secondary affinities, some affinity is left over in the compounds in which such affinities are exercised. in the early days of structural formulae, chemists were satis- fied with plane representations upon paper, in which lines were drawn proceeding from the symbol of the clement in accordance with its valency, thus | | then models were constructed of balls with holes drilled into them, in number according to the valency of the elements rep- resented. other atoms were attached by inserting rods into the holes in the balls. no attempt was made to give any special direction in space to the affinities thus signified. gradually, it was realised that such formulae and models implied both too much and too little. on the one hand, they gave rise to expec- tations which were not fulfilled. thus, two pictures can be drawn of a compound of the type ch.cl h- —oo—- cl cl | | h—c—ii h—c—cl | | cl h in the one, the two atoms of chlorine are opposite, in the other they are contiguous. exhaustive inquiry failed to discover any difference in the compound, however prepared. on the other hand, many compounds were found to exist which were of the same composition but structurally similar—differing only in one peculiar respect: in that one was the morphological and optical chemistry opposite of the other. when the crystal of the one form was compared with that of the other, they were scen to be identical, except that the one was a mirror-image of the other, as a right hand to a left hand. there was a corresponding difference in the behaviour of solutions of the two compounds in plane polarised light—the rays of light being twisted in one direction by the one, equally (if the solutions were of identical strength) in the oppo- site direction by the other. this was pasteur’s great discovery, made in 1848. van't hoff, in 1875, building upon pasteur’s suggestion, that such compounds were geometrically different in structure, resuscitated and expanded pasteur’s suggestion that carbon was itself a tetrahedral unit and in his chemisiry in space fully developed a doctrine of spatial structure already fore- shadowed by kekule, which has proved to be very generally applicable. representing carbon by a regular tetrahedron (such as may be made by joining together four equilateral triangles), he drew attention to the well-known fact, that tf one, two or three faces only were different, two being alike, object and mirror image were alike—they could be superposed. hf all four faces were different, the image could not be superposed upon the object —such compounds were asymmetric, their models could not be halved, as could those in which only two or three faces were different. he was able to show that all known optically active compounds might be regarded as constituted in the manner suggested and to predict that all such compounds would be optically active. his forecast has been verified in all respects (see isomerism, 14.881). van’t hoff represented the four affinities of carbon as pro- ceeding from the centre of mass of the regular tetrahedron to the four solid angles. they therefore meet at an angle of 109°28’. he represented compounds in which carbon atoms were united by single affinities by tetrahedra joined at their apices—not as filling space. sir william bragg has shown, by means of x-rays, that in the diamond the atoms of carbon are thus related—each being surrounded by four others, each of the four meeting it at the tetrahedral angle (sce crystallography). a model of the diamond—a sheet of atoms in the diamond—may be made by arranging cardboard tetrahedra side by side, placed alternately base downward and base upward (choosing any face arbitrarily as base). the van’t hoff generalisation has thus been verified in its entirety in principle. } van’t hoff doubtless found more than sufficient material needing discussion to extend his explanation and correlate it with the crystalline form of solids. the “ solid significance ’’ of the doctrine was never considered by him. before dealing with this, it is desirable however to consider certain peculiarities in the behaviour of carbon. carbon contbinations —the atoms of most of the elements seem to be capable of uniting with themselves and even with others only in very limited numbers. the number of carbon atoms which can unite with one another, however, appears to be illimitable and there seems to be no falling off in grip as the number grows. the simplest hydride, ch, is but the beginning of a long serics of hydrocarbons, known as the paraffins, in all of which carbon and hydrogen are present in the relative pro- portions in which they occur in methane, so that they may be represented by the general formula c,ho.+2. like methane, these are all saturated, in the sense that they do not combine with any substance whatever. the name paraffin is derived from the fact, that especially chemically, they have little affinity for chemical agents in general. they may be oxidised, they are acted upon by chlorine and bromine, yet not easily. they yield only substitution derivatives, i.c., one or more hydrogen atoms are exchanged for an equivalent radicle. thus— | ch;cl + cl, = cierch + hcl ch.cl, + cl, = chc) + hcl ciich + ch = cc + hcl the solid paraffin, used in making candles, is a mixture of higher members of the series. petrol contains low terms—such as hexane, cshu, heptane, c;his, etc.—the illuminating and ll chemistry lubricating oils from petroleum are mixtures of terms inter- mediate between those in petrol and paraffin. organic chemistry has often been spoken of as the chemistry of the hydrocarbons and their derivatives, because all other compounds may be derived from the hydrocarbons by processes of simple substitution, by the introduction of various simple atoms or compound radicles (groups of atoms) in place of one or more of the hydrogen atoms of the hydrocarbon. the paraffin hydrocarbons may be built up to any desired degree of complexity by various simple methods. thus methane is converted into methylmethane or ethane by the process in- dicated in the equation: ch,i + ch,i + 2na = ch;:-ch; + 2nal etnane is converted into the next term, propane, in a similar manner: chi -- ch;-ch.i -b 2na or into tetrane: ch;:ch.l +- ch,-ch.i a 2na = ch;:ch.-ch,chs3 a 2nal it will easily be seen that there are two ways of introducing ch; (methyl) into propane: | ch;-ch2:ch.:chy ———~ ch;-cha: ch; —— ch3-ch(chs3)e tetrane propane isotetrane in one the “ chain ” is simply extended, in the other, two links are associated with the one terminal link. three and even four links may be attached to one, as in trimethylmethane ch(chs); and tetramethylmethane c(chs3 )4. compounds of the same gross or molecular formula, differing in structure, are termed tsomeric (sce 14.881). the successive terms in the series are termed homologues. they are homolo- gous in the sense, that apart from differences in physical prop- erties, boiling point, density, etc., they are generally alike in their chemical behaviour. this is true also of the isomeric hydro- carbons. hydrocarbons are all more or less easily attacked by chlorine or bromine but not by iodine; the iodo-derivatives are obtained by indirect methods. they are also easily oxidised but the product is often, if not usually, a mixture, as the products are more easily oxidisable than the original hydrocarbons. we speak of oxidation but in reality the process is always initially one of hydroxylation and, for the sake of simplicity, may be represented as effected by perhydrone, h.0.. thus ethane is converted into ordinary fermentation or ethylic alchol: ch;-ch; + ho-oh = ch;-ch.(oh) + hoh the primary product of the oxidation of methane, in like manner, is methylic alcohol—the alcohol of wood spirit ch, + ho-oh = ch;-oh + hoh the alcohols are the organic analogues of caustic soda (sodic hydroxide) thus— na-oh + hcl = nacl + hoh c.h;-oh + hcl = c.h;cl + hoh this is true so long as only the (oh) radicle be attacked. in the carbon compound, however, the hydrocarbon radicleis attackable, as in the oxidation process: ch;-ch2-oh + ho-oh = ch;-ch(oh), + oh: ch3-ch2-oh + ho-oh = ch;(oh)-ch.,(oh) + ohe both actions take place, according as one or other oxidising agent be used. the two products differ in a characteristic manner, the one being unstable, the other stable. whenever two hydrox- yls are associated with a single carbon atom, the product is unstable, readily losing the elements of a molecule of hydrone ch;-ch.(oh)z = ch;-coh + oh2 aldehydrol aldehyde in aldehyde, the dyad oxygen atom takes the place of two monad hydrogen atoms in the hydrocarbon and of the two monad hydroxyl radicles in the alcohol which is the initial product of hydroxylation. hydroxylation may be carried a stage further ch:;: ch.-chs3 + 2nal 591 ch;:ch(oh). + ho-oh = ch;-c(oh); + oh: the trihydrol thus formed is even jess stable than the dibydrol and easily loses hydrone ch;-c(oh); = ch ;-co(oh) + oh2 the product, acetic acid, is methane in which a single atom of hydrogen is displaced by the radicle carboxyl, co(oh). this radicle is characteristic of organic acids generally—the term acid is given only to compounds which contain it or an equivalent radicle, such as so3h. methane may be oxidised in the following manner:— chs+ho-oh = ch;-oh+oh, methylic alcohol ch.(oh)+oh, formalde- hydrol ch(oh)3s+ohs formacid- hydrol ortho- carbonic acid. formaldehydrol passes by dehydration into formaldehyde, ch,(oh)., formacidhydrol into formic acid, orthocarbonic acid into carbonic acid, co(oh)s, ultimately into carbon dioxide. the possibility of the formation of isomeric compounds must not be overlooked. thus, propane may be hydroxylised only to two monohydric alcohols but each of these may conceivably be oxidised in several ways, thus ch;-ch2ch,-oh propylic alcohol ch.(oh)-ch2-ch,-oh ch,;-ch(oh):ch,-oh ch;3:ch,ch(oh)e | these dihydric alcohols are all known, though they are not produced exactly in the manner indicated. attention should be drawn to the isomeric compounds ch;-ch2:ch(oh): deprived of hydrone, these yield ch;-ch2coh propionic aldehyde both keto-compounds, closely related in character, the one, how- ever, an aldehyde, the other a ketone. the difference between these is particularly well brought out by their behaviour on oxidation ch;-ch2ch(oh): + ho-oh = ch;-ch2-c(oh)s + oh2 ch;-c(oh)2-ch; + ho-oh = ch;-c(oh); + ch;-oh the one yields the corresponding acid, a characteristic of alde- hydes, the other is broken down. actually, the methylic alcohol shown in the equation is further oxidised as it is produced and escapes recognition. both propaneglycols should yield a stable trihydric alcohol on further hydroxylation ch,(of)-chzch.(oh) ch,(oi)-ch(oh)-ch, ~sch,(oh)-ch(oh)-ch,(oh)— actually, this change has not been realised but the alcohol indicated is the well-known substance glycerol (glycerine), obtained as a by-product in making soap, by saponifying hard animal fats and fatty oils with caustic soda. reduction.—hydroxylation (oxidation) is the process in- volving the displacement of hydrogen by hydroxyl (oh); it is one of the most important of natural processes, especially of those in a downgrade direction. the reverse operation, the dis- placement of hydroxyl by hydrogen—reduction—is equally frequent and important, especially in upgrade changes. more often than not the two occur, if not in conjunction, in rapid ch,oh+ho-oh = ch.(oh).+ho-oh = ch(oh);+ho-oh = ch;:-ch(oh)-chs isopropylic alcohol ch;:ch(oh):ch2-oh ch;-c(oh)s:chs3 ch;-c(oh)2:chs chs3-: co: ch; acetone 592 succession. all the changes above considered are reversible by hydrogen (atomic) acting “in circuit’ with the hydroxy compound. hydroxylic interactions.—although similar in their functions to metallic hydroxides, the alcohols are in one respect strikingly singular in their behaviour, inasmuch as they do not give rise to conducting solutions when dissolved in water. metallic hydrox- ides and acids interact immediately; alcohols are but slowly attacked by acids. the apparent outcome of the interaction of alcohol and acid is the substitution of the acid radicle for the hydroxylic radicle. actually, the interaction may be more com- plex and involve a structural change. to give a specific illus- tration, alcohol and hydrogen chloride do not interact, except in the presence of water. hydrogen chloride and water together, however, form an electrolyte. the process of interaction, in their presence in association (as a composite electrolyte), may be less direct and more complex than is commonly supposed, perhaps broadly as follows :— h | h | cl | ch,-cu,(oh) oc j) gaech ones hi ist ho-che h ella ve ——> [oh.+]chs-chci(h) cl+ the if in brackets is that which may be supposed to take the place of (oh) oviginally in the alcohol. some such process as this may be at the root of the walden inversion, in which an asymmetric compound is produced of opposite sign to that taken, the change being reversed when the inverse interaction is effected. it is probable that such “ inversions ” often happen unperceived, and that not a few inferences of structure may be affected by the occurrence, particularly in the sugar group. the active part taken by “ a neighbouring hydrogen atom ” may also be at the root of the “ steric” hindrance observed in “ etheri- fications.” | unsaturated hydrocarbons. —so soon as hydroxyl] is introduced into a saturated hydrocarbon—one in which the four affinities of the carbon atom are separately satisfied—a condition of in- stability is established. the hydroxyl tends to separate with hydrogen as hydrone—thus alcohol gives ethylene, c:h;-oh = c.hy+oh:. “ dehydration,” in reality, is an indirect process and may be effected in various ways, as by heating alcohol with either sulphuric or phosphoric acid: a sulphate or phosphate is first formed and decomposed. the loss of ohm and h by alcohol is equivalent to the withdrawal of two atoms of hydrogen from the hydrocarbon ethane, c2hs. the operation may be repeated —ethylene may be converted into acetylenc, c2h2, now a com- mon frequenter of society in company of the motorists and largely used in welding and cutting steel. it is also made more directly by heating carbon together with lime, cao, in an electric furnace, so producing calcium carbide, ca:cs, which ts trans- formed back into lime and acetylene by the action of hydrone (water) thus: casc.+oh2= 2ca0+c.he ethylene differs by two units, acetylene by four, of affinity from ethane. both hydrocarbons combine with bromine, giving rise to compounds of the ethane type, cohybrz and coh.bry the structure of these unsaturated hydrocarbons is not yet settled. frankland said originally: ‘‘ let it be assumed that two affinities of the one satisfy two affinities of the other carbon atom in ethylene, three of the one, three of the other in acetylene— write h.c=cit, and hc=ch.” it was so assumed—the con- ception was simple and easily committed to memory. van't hoff said, join two tetrahedra edge to edge torepresent the carbon in ethylene, solid-face to solid-face to represent acetylene: the mandate was obeyed, so open to suggestion are we. whether or no such conjunction be possible, the fact remains that both compounds behave as if they were unsaturated and full chemistry of energy. julius thomsen, as the result of his determinations ef “heats of formation,” has contended that actually less work 1s done in ‘“‘ doubly ’-combining two carbon atoms, still less in “ trebly ’-combining them, than in combining them by single affinities. for the present, it is better to term the one “‘ linkage” ethenoid, the other acet(yl)enoid, than double or treble bonded. the ethenoid linkage is commonly repeated but not the acetenotd. the paraffins (c,hen+2) and the corresponding ethenes (cshoa) and acefenes (c,hon+) are all open-chain hydrocarbons: car- bon atom is united to carbon atom in a continuous series, we mav now say, in a zigzag, each setting to the other at the tetra- hedral angle 109° 28’. this conception is now found to be tn agreement with the verdict given by x-rays. phenoid carbon.—a change comes over the scene as more and more hydrogen is removed and the compounds become less and less saturated algebraically. faraday, a hundred years ago, discovered in the liquid condensed from “ oil gas ’’—the gas ob- tained by decomposing oil at a red heat—the hydrocarbon, c,li,, which is now known as benzene. theoretically, it is de- rived from the parafiin hexane, cshu, one of the chief con- stituents of petrol of low boiling point. it is a highly refractive liquid, whence the name phene, which was given to it by laurent, obvious to-day in phenol (carbolic acid). it crystallises readily. benzene is nearly saturated. chemists account for this fact by supposing the six carbon atoms arranged in a “ closed chain or ring,’ and that each carries a single hydrogen atom. the distribution of the fourth affinities has given rise to much controversy, in large part futile, because no clear conceptions were behind it and discussion was based upon imperfect appre- ciation of the facts. chemical formulae, in the main, are but symbols of character—“ shorthand ” expressions indicative of the general behaviour of the compounds represented. they also portray the general structural relationships or arrangement of the atoms. they do so, however, only in terms of certain con- ventions. it has been customary to represent ethylene as hz.c=ch.. to represent benzene as containing three pairs of carbon atoms related as in ethylene, which is often done, is to use a symbol that is in no way an expression of the facts. the general chemical behaviour of benzene is that of a but weakly, though not of a highly, unsaturated compound, and it is ob- viously peculiar in its behaviour. fortunately, the extraordt- narily complex chapter of the chemistry of its derivatives may be written irrespective of the structure of the hydrocarbon itself. regarding it as a closed system, with six symmetrically arranged hydrogen atoms, all that is necessary ts to represent it by a regular hexagon with h written at each of the corners. deriva- tives are formed by displacing one or more of these hydrogen atoms: when several are displaced the derivatives vary in char- acter according to the relative positions of the displacing racticles these are easily indicated by numbering the positions relatively to some one, thus i 6 2 5 4 the relationship of thousands upon thousands of compounds may be satisfactorily represented by this simple device. by, as it were, soldering phene upon phene, polyphenes of any desired complexity may be produced. coal tar contains three a to a tehet ies) such: \ ae benzene naphthalene anthracene calls croll cul these are the foundation stones upon which the great modern dyestuff industry is built. the various “ chars” (charcoals) chemistry are probably highly complex compounds of this pattern with but a very small number (in proportion to the carbon atoms) of hydrogen atoms, which prevent the carbons from lapsing into the diamond state. diamond is one great carbon-phene—the benzene unit is but a small, highly symmetrical block dissected out from a single layer of atoms in the diamond and clothed with six hydrogen atoms. model representations —to obtain a model of the diamond, it is only necessary to make a considerable number of regular tetrahedral groups of equal spheres and to arrange these inter- locked in sheets, placing them alternately upon base and upon apex, then piling sheet upon sheet, all closely interlocked. tach unit tetrahedral group within such a close packed mass will be equally surrounded with four other like tetrahedral groups inter- locked in face contact. each face-centre between two blocks being a centre of affinity, the model will embody the conception that the carbon atom has four equal affinities ranging outwards and operating, in so far as other carbon atoms are concerned, at the tetrahedral angle, from the centre of the mass. occasion may be taken here to point out that the individual atoms at the surface of any mass of diamond must each have an affinity free. this must generally be true of all compounds. it does not follow, how- ever, that such aifinitics have their full force. an attempt to correlate crystalline form with chemical struc- ture and develop solid models of complex carbon compounds was first made by barlow and pope in 1899. they advanced two primary propositions—first, that valency may be given volume significance. taking an arbitrary sphere of unit volume to represent a monad atom such as that of hydro- gen, a sphere of twice the volume was used to represent a dyad atom such as oxygen, one of thrice the volume to represent a triad (nitrogen), and one of quadruple volume to represent the tetrad carbon. second, that the relative valency volume re- mained the same in a scries of related (corresponding) compounds, though the absolute volume might vary. this assumption is made to satisfy the facts of isomorphism—for example, in a series such as that of the three halides, nacl, nabr, nal. if the den- sities of these salts, referred to molecular proportions—the volume occupied by the gramme molecular proportion-—be taken and the assumption made that the sodium maintains its relative volume in the three compounds, the volume increases from chlorine to iodine. this is true generally. pope and barlow assumed that there was mutual adjustment and that the 1:1 volume ratio was retained in all the compounds. this is not only rational but apparently necessary. unfortunately, the use of spheres varying in volume entailed the construction of models on which the units were not close packed, and the attempt was unsuccessful on this account. mr. barlow has elaborated a simpler method of treatment which appears to satisfy the conditions to be met. using a sphere as unit of valency, the dyad is represented by two, the triad by three, the tetrad by four such spheres. models so con- structed can be ‘‘close packed”’ to any extent. if a mass of spheres be compressed, the units are ultimately reduced to dodecahedra and are then in contact over their entire surface. mr. barlow adopts such a dodecahedral unit in constructing his models. the carbon atom is represented by a pyramid of four dodecahedra. when two such are brought together to represent atoms united as in the diamond, the faces interlocked may be said to be eerfaces, as surfaces of three of the four constituent units of the tetrahedron are present. ascries of tetrahedra united in this manner, in a rectilinear zigzag, represents the parafiin structure. lines drawn between the mass-centres of contiguous units meet at the tetrahedral angle in a zigzag. whilst such straight chains may be dissected out of a sheet of diamond atoms to form the paraffins and their derivatives generally, benzene and the phenoid compounds may be built up from hexagonal blocks—sets of six carbon units— dissected out from the diamond sheet. to produce the benzene model, three ‘‘ sameway” oriented tetrahedra should be placed symmetrically, each resting upon a surface, apex meeting apex at a common centre; then, 593 three other similarly arranged tetrahedra should be placed upon these, so that each rests upon an apex, thus filling the three spaces between the lower three, the six together forming a block in which three affinities appear at the upper and three at the lower surface, each of the carbon units in the mass being united to two contiguous units. in such models there are two layers of valency units. to typify benzene, six hydrogen units have to be attached around the hexagon, one being assigned to each carbon atom and alternately placed one in the lower, the other in the upper plane of valency units. the engaged affinities are thus all operative in two planes, as it were. mr. barlow has thus constructed solid, close-packed geo- metric models of a large number of benzene derivatives, taking into account the crystallographic data. in all but a few cases the models are a direct representation of the compound. in some instances, notably in that of parabromophenol, to obtain a model which is in harmony with the crystallographic data it is necessary to effect a slight readjustment of some of the units attached to the carbon complex, which remains fixed and in- variable. the shift is of an entirely rational and simple character. the hydrogen unit remains attached to its appropriate carbon atom but is moved from an upper into a lower—or the reverse— plane of the carbon unit. the models serve to bring out relationships which are patent to the chemist but not hitherto quantified, particularly in connection with the residual affinities shown by compounds generally. the higher paraffins and fatty acids are solid compounds, maybe of high melting point. it has always been difficult to account for this fact. in the model of a paraffin, the carbon skcleton is a two- layered structure like that of benzene; but whereas, in benzene, the carbon units rest upon “ terfaces,” in the paraffin the chain rests upon a succession of simple dedecahedral faces: the carbon units are, in fact, skewed. the hydrogen units are arranged in pairs on either side of the chain, therefore wot at the tetrahedral angle; again, the affinities are exercised in two planes, those of the single carbon atom. in consequence, although each carbon affinity is engaged, it is but “‘ partly covered or spoilt ’* and there is a considerable uncovered carbon surface. when the unit models are superposed or conjoined these surfaces come into apposition, thus typifying the exertion of what for want of a better expression, may be termed residual affinity. it is impos- sible, using such models, to typify carbon atoms as united by more than single “ full ” affinities. only two forms of union seem possible, one that described, characteristic of paraflin and bezene; the other less complete in one sense, though it is such as to affect and “ spoil” two affinities of each atom. in the paraffins, three dodecahedra in each carbon unit are concerned in the single union. in the second geometrically possible mode of union, the jaws as it were of two atoms are interlocked—the result is that only two dodccahedra of the one are in contact with two of the other; the dodecahedra, however, do not belong to one “ affinity face ” as in the parafiin but to two. the model does indeed typify the eminently unsaturated condition of the ethenoids. in the acetenes, the third affinity ot each of two carbon atoms is frankly to be regarded as unsatisfied, if the model be in any way a representation of the actual con- ditions. whatever their ultimate value in connection with crys- talline forms, such solid geometric models are undoubtedly bound to prove of great importance in the study of structure; their use, however, would seen to entail the use of a “‘ geometric sense ’ but little developed hitherto. colour.—whatever be the nature of theethenoid form of union, it is the cause especially of marked optical peculiarities and in many cases of visible colour. it is almost possible to assert that coloured compounds are all of one type—all ouinonoid. quinone is a benzene derivative, formed by the removal of the two hy- drogen atoms from the two hydroxyl groups in paradihydroxy- benzene (the photographer’s hydroquinone) or quinol son 0 yo the white quinol becomes yellow. to mention other simpler ho 094 cases, mercuric iodide, which is a yellow or red crystalline solid, is colourless in certain solutions. probably it is present in these as the simple molecule hgi2, and in the solid form as a complex (hgi,)x. iodomethane and diodomethane, chi3l and chel:, are colourless liquids; triodomethane (iodoform) is a yellow solid. in these iodo-compounds the appearance of colour is probably determined by the “residual affinity ’’ of the iodine. it is un- certain whether or no the simple molecule of iodoform be col- oured; perhaps it is not, and thesolid may be better formulated as (ch) i i i i i j (ch) and the assumption made that the three unsaturated centres de- veloped between the three iodine atoms co-operate to produce visible colour. if so, a sufficient number of simple molecules of mercuric iodide may be supposed to associate to give at least three unsaturated ethenoid centres. the faint blue colour of liquid oxygen may well be due to the association of several mole- cules in a complex system. the three centres in quinone are conceivably the phene nucleus itself plus the two unsaturated co groups. it is, however, pos- sible that the simple quinone molecules are associated—through the co group—and that the origin of the colour is in part extra- molecular. this is certainly true of a number of cases in which colour is apparent. when the number of unsaturated centres is increased, the colour is intensified and almost reaches black. the blackness of charcoals is perhaps to be explained in this way: probably these and graphite are highly complex molecules in which carbon is present not in one form as in diamond but as ethenoid carbon, together with phenoid and paraftfinoid. it 1s possible that it will ultimately be found that there is but one form of carbon—diamond—and that the supposed allotropes contain a very small proportion of hydrogen—that they are com- plex hydrocarbons in fact. organic chemistry.— organic chemistry, now a vast science, in- cluding hundreds of thousands of compounds, is entirely built upon the carbon foundations which have been described: the paraffinic and the benzenoid, the one open, the other a closcd system. infinite as is the variety of compounds, they are nearly all formed from the hydrocarbons by the introduction of oxgyen (in relatively few cases, sulphur) or nitrogen, sometimes both, in place of one or more atoms of hydrogen. no two compounds are alike, and yet, within families, the resemblances are close. at bottom, the power of the carbon atom to combine with the carbon atom almost indefinitely is the reason why so many carbon compounds are possible. no other element appeals and clings to itself in the same way. no other element could well give rise to life. we are essentially creatures of carbon, using water as lubricant and oxygen as stimulant. perhaps the greatest work before us is to interpret molecular structure and the func- tions of the materials made use of by the organism in terms of solid geometry. we shall then begin to have feeling knowledge of ourselves. to be a chemist, it is necessary to have full appreciation of the characteristics of the families that enter into the world of carbon and to be in close acquaintance with many of its individuals. it is a difficult but fascinating occupation: once engaged in, the proper spirit of wonder and reverence being developed, it will be found to be the forecourt to many mansions of marvellous beauty. we can only deal with life as built upon life, but our know!l- edge of the materials upon which its images are graven and of the graving processes is already astounding. yet we are only on the outermost fringe of the inquiry, the difficulty of the problems to be solved is clear only to those who are absorbed in the study. the beauty of the solutions already found is in many cases be- yond description, but to how few is this revealed! the plant is the great builder. beginning with the simplest materials, it raises these to levels at which they become available to the ani- chemistry mal organism, whose constructive power is limited to the arrange- ment and incorporation, not of simple bricks such as are handled by the plant, but of larger units previously fashioned by the plant. plant, in turn, is dependent upon soil, as well as upon sun. we are indeed of the earth, earthy whilst children of the sun. plant activities —falstaff, in his day, could well say, ‘“ the world is mine oyster, which i with sword will open:” such was the method of old. to-day, we work with knowledge, and hope to have done with swords—for a time, at least; the more we use our knowledge the more our cry may be, “* the world is one great gasholder, whose holding we with our lungs devour.” as the rays of the rising sun strike the earth, they enter upon their daily task of keeping the holder filled, whilst its contents are constantly consumed by plant and animal alike, chiefly by the latter. our great luminary has been thus engaged throughout time, and much of his energy has been founded for us in ways and forms of which we take too little cognisance. we dispute much over coal and oil but take scant notice of oxygen—without which they would be worthless and life impossible: yet we have no full understanding of the ways of that oxygen, we pay little heed indeed to its marvellous power. the initial act, on the part of the plant, is the absorption of carbon dioxide—present in the atmosphere in the minute pro- portion of only about three parts in ten thousand. under some conditions, where much organic matter is undergoing decay, more may be present and there is much evidence that growth is more rapid when the concentration is above the normal. it is beyond question that oxygen is evolved, in proportion to the amount of carbon dioxide assimilated, as if action took place in the sense of the equation:— co.+ oh2= com2+ 02 that is to say, as if the final oxidation product of carbon had been lifted back and up twosteps towards methane, ch,. noone doubts the explanation, although the compound coiis, formaldehyde, has never been shown to be present in the plant cell by means which preclude the idea that it has not been developed in the course of testing. chemists generally accept the explanation, because it appears to be the only one that will satisfy the con- ditions of the problem, the visible products of assimilation being such that not only may their production be accounted for by assuming that ‘“formaldehyde”’ is their progenitor, but it is scarcely possible to suppose that they are produced in any other way. moreover, formaldehyde, in the guise of ch.(oii).,, its hydrol, is a compound of intense chemical activity, and it is not to be supposed that it could accumulate in the vegetable cell. this is not to say that we know precisely how the aldchyde 1s produced: we do not. still, it is already proved that assimilation only takes place under the influence of light absorbed by the chlorophyll, in the green region of the visible spectrum. the process may, therefore, be regarded as an electrolysis. every chemical interaction, be it remembered, is an electrolysis ef- fected by light, in which water is electrolysed in circuit with carbonic acid, this latter being eventually reduced to the alde- hyde, whilst the complementary product, perhydrone, is resolved into oxygen and water. written empirically, the change may be expressed by the equation :— co(oh).+ (h 6 aed oh), _ coh,+ 20h»+ 2ho-oh if so, the oxygen in reality is derived from water. the carbonic acid primarily serves the purpose of taking charge of the hydrogen which must be separated from hydrone to produce oxygen. the reduction product is alone of special (constructive) value to the plant; oxygen is returned to the atmosphere, in place of the car- bon dioxide removed, sooner or later to piay a destructive part, but, in so doing, to let loose and pass on the energy derived from the sun. much energy from the sun is also stored in the form- aldehyde. the quantity of solid formaldehyde corresponding with the formula (cii.o) expressed in grammes (30¢ grammes, since c=12, h=1, o=16), when burnt, gives rise to 122,880 grammce-calories, that is to say, sufficient heat to raise the tem- perature of this number of grammes of water 1° centigrade. chemistry 995 the contained carbon and hydrogen, if burnt alone, the former | once suffers internal change and is converted into the corre- in the form of charcoal-carbon, would furnish 96,960+-68,360 gramme-calories. formaldehyde, therefore, has within itself about three-fourths of the energy of the contained carbon and hydrogen. it is thus shown how great a work is done by the sun. chlorophyll.—as chlorophyll is concerned and solar energy made operative through its absorptive action, it is necessary to assume that the electrolytic circuit 1s one in which the chlorophyll is included. chlorophyll is a nitrogenous compound of great com- plexity and one of the most remarkable known. it is closely re- lated to blood haematin, but, whilst iron is a characteristic con- stituent of the latter, magnesium is similarly the outstanding constituent of chlorophyll. haematin has the power of com- bining with oxygen; it combines even more firmly with carbonic oxide (co), but not with carbon dioxide. chlorophyll shows no such associative tendencies, yet to explain its action we are al- most forced to assume that it can combine, at least loosely, with carbonic acid. it has been surmised—it is only a surmise—that the association is through the magnesium atom, that this be- comes partially unclasped through the action of carbonic acid, so that an acid carbonate, xo-co (oh), is formed. that such a carbonate might undergo reduction, in an electrolytic circuit, to the formaldehydrol derivative x-o-ch2(oh) is possible, to say the least; indeed, it is probable that it would. still, as chlorophyll is a pyrole derivative and laden with nitrogen, it is conceivable that it may act basically, apart from its magnesium. more it is impossible to say: the problem is one, however, which should not be put aside. whatever be the precise nature of the operation whereby form- aldehydrol is produced, we have no reason at present to be- lieve that it is otherwise than the sole immediate product of solar activity. in like manner it is at least probable that the higher carbohydrates which are formed by its condensation are the only compounds which are in the direct line of succession as solar products; of these, be it said, cellulose is the only one which is of structural value as cuticular material. the plant cell is a laboratory of wondrous activity. within it are built the great variety of products which form the plant—quietly, without per- ceptible ostentation, at ordinary temperatures, often in the dark, underground, as in the potato tuber. thus we have been unable to prepare starch or even cane sugar. to imitate the operations of nature we need most elaborate and expensive appliances, and often work at high temperatures and pressures. when we think of the way in which nitrogen and hydrogen are converted into ammonia in the root nodules of leguminous plants, apparently by a minute organism living an imprisoned, airless life—when we contrast this with the great array of pumps, compression vessels and many other mechanical appliances used in the factory to the same end, we may indeed hang down our heads in very shame at our ignorance of all that is fundamental in the minute operations of nature. to pour such material, so made, as ferti- liser upon the soil, when the humble bacterium by which it is populated can do the work on the spot if only properly encour- aged, may some day come to be regarded as soil sacrilege. formation of carbohydrates—under laboratory conditions, formaldehydrol rapidly undergoes change in presence of a mere trace of an alkali. the product is a complex mixture and has never been successfully unravelled: it contains fructose, however, one of the components of cane sugar. the process of change is only partly understood, and is in doubt, so far as the precise nature and succession of the changes between aldehydrol and sugar 1s concerned, but is, in essence, a condensation and typical of a great numbcr of up-grade changes which take place under natural conditions. it may therefore well be discussed at length. perhaps three molecules interact simultaneously thus:— chh-oh chh-oh | chi-oil = ch-oh+ 20h2 | ch-oh-oll ch (oi). this product, glyceraldose (hydrol), the aldehyde of glycerol, at sponding isomeric ketone—glyceroketose (hydrol), chh-oh ch,-oh ch: oh | | | | | ch-oh:-o ch-oh ch,-oh these triplets interact, in pairs, in various ways. the production of fructose may conceivably take place in the following manner, by the condensation of glyceraldose and glyceroketose, ch:2:oh ch, -oh | | gly ceraldose ch-oh ee (hydrol) | 7 ch(oh)s ch-oh = | ch, -oh chilo glyceroketose | | | (hydrol) coe ais ch2-oh ch.-oh the production of glucose may be represented as involving the interaction of two molecules of glyceraldose (hydrol), ch,-oil ch.-oh ch-o oil lees: ch-oh+oh, ch.-oh | 7 lats cil-ou er laat: ch(oi). the formulae here used are mere paper-written expressions and not intended to indicate actual structure—they do so only broadly. it will be noted that in the glucose formula four of the carbon atoms, and in the fructose formula three, each carry four different radicles; the two sugars are therefore struc- turally asymmetric materials and should be optically active. the natural products are but the compounds produced in the labo- ratory, are not optically active simply because the latter are mixtures of compounds of opposite optical activity. in point of fact, variations in internal structure are brought about by merely varying the relative position of the (oh) groups in the ch(ohl) member of the structure. in all, 16 isomeric glucoses are possible: these form two sets of eight, corresponding terms in which are of equal, opposite structure and optical activity. the three isomeric natural sugars, glucose, mannose and galactose, are represented by the following expressions, showing the relative arrangement of the hydroxyl groups in the asymmetric members:— -ch(ow)2 ch(oh)2 ch(oh)2 hc:-oh ho-ch hc:oh ho-ch ho-ch ho-ch eed oe ho-ch hc-oh eon itc-oh ieee me -oh ie -oh glucose mannose galactose the structural relationship between these three forms is of a very simple character. if the position of the topmost oh group in glucose on the right of the formula be reversed, the formula becomes that of mannose. as a matter of fact, this change grad- ually takes place, to a slight extent, when merely a little alkali is 596 added to a solution of glucose. the process is probably that already pictured of glyceraldose:— ch(oh), ch(oh)2 ch.oh j hc-o1 | = | + oh, | hc-on c-oh \y ch(oh): ho. [ ja | the peculiar ethenoid linkage developed by withdrawal of hy- drone from the aldehydrol may be broken on either side and the oh may be restored, either in its original position or reversed. the change from glucose to galactose may be pictured in an equally simple manner. assuming either that the glucose be first resolved into two molecules of glyceraldose, or that the two sugars be each formed directly from two such molecules, ch(oh). chow), = ch(om): i ‘a ss dts hc-ow | h-chh ho-ch ho-ch a b- ho-ch-ot hcoh ho-ch on 11c-oh he-ou ch, oh ch-oh ch;oh either glucose will be reproduced or galactose will be formed, according as either the oh group marked (a) or that marked (b) be removed in the extruded molecule of hydrone. the position of only one of the oh groups is changed. these are not mere matters of speculation: such changes actually happen, before our eyes, in the laboratory. optical activity-—-when compounds are produced artificially which are potentially (by structure) optically active, the two optically active forms, of equal opposite activity, are both pro- duced and in equal amounts, so that the product is optically inactive. the chances of the action going this way or that, un- less specially directed, are equal. in nature, all such compounds are produced initially in the one optically active form—nature, as it were, is one-handed and wears but a single glove. nature’s factory turns out only gloves for, let us say, right-handed wearers. when both appear, as happens in a few cases, there is reason to believe that a change has taken place after nature has ceased to exercise her directive influence. | of all the facts disclosed by the study of natural products, this restriction placed upon herself by nature is the most remarkable. the discovery is the outcome of pasteur’s initial, most wonderful, prime discovery that racemic acid, an optically inactive product got from wine-lees, could be resolved into equal parts of ordinary right-handed tartaric acid and of a left-handed twin thereof. it is an important consequence of this generalisation that natural chemistry is, in a sense, simpler than laboratory chemistry. how is the natural process by which a sugar such as glucose is formed to be pictured? it is as if the formaldchydrol molecules were threads the two ends of which are passed through contiguous holes in a piece of canvas. a number of such threads, being thus arranged, may obviously be tied together at the back of the canvas in various ways and the loose ends then clipped off, leaving distinctive elements of the thread arranged in some pattern on the front. such a pattern might conceivably be produced by lowering upon the canvas a plate with holes through which the threads could be drawn only at certain points, and thereby deter- mining the ways in which they could be tied together. in the plant, more probably, the reverse influence may be at work. the pattern may exist in the plant in the form of the substance to be produced: a sugar molecule may conceivably be formed upon what is practically a sugar molecule; that of starch upon a starch molecule; hence the apparently immediate appearance of starch. if such be the case, we can understand the formaldehydrol chemistry molecules becoming properly placed upon the guiding moleeule, particularly in virtue of the attraction exercised by the (oh) groups in this upon those in the corresponding positions in the formaldehydrol molecules, leaving others in the position of loose ends to be snipped off at the right moment. when models of benzene derivatives such as have been described are packed together to form the crystal, more often than not they form a stepped pavement, as it were, alternate units being at one or other of two levels. starch may well be so constructed, and it is possible to picture a series of formaldehydrol molecules dropping into place, in orderly arrangement, upon such a platform, ready to be tied together, enayme action.—how is the tying done? it may be asked. the operation is so easily effected in the laboratory that no special mechanism may be required. a trace of alkali or even acid may suffice. on the other hand, there is much evidence that, under natural conditions, the more complex carbohydrates are usually broken down through the agency of special agents, known as enzymes, therefore, it is at least probable that they are formed by the converse process, as such interactions are known, in many cases, to be reversible, and should be in all, though the point of equilibrium may be so near to the side that the change may appear to be unilateral. the general equation of enzymic hydrolysis may in fact be written thus:— a'b’ +e5xohsss4/(h) +b’(oh) eax. the difficulty that arises in the attempt to apply this general- isation is that the necessary agent is not always obvious. thus, it is known that the constituents of cane-sugar, glucose and fructose both travel down in large quantity from the leaf to the bulb, and there become associated as cane-sugar: the bulb, however, does not contain the enzyme invertase, although this is present in the growing leaf. ‘the enzyme appears to travel down into the bulb only when the growing period sets in, and the store in the bulb is utilised in forming a new season’s growth. a further structural peculiarity in the sugars may now be referred to, asit isone that must be taken into account in discuss- ing their formation. in the paraffins, as already explained, the carbon atoms are simply arranged in a series or row, atomic centres meeting at an angle of 109/28”, at successive corners of a zigzag. in the phenes, the angle of the approach of the carbon atoms may be supposed to be the same, but they are arranged in compact closed systems—in sheets of more or less frequently repeated hexagons. the sugars are also peculiar. glucose is derived from the alcohol mannitol, which, in turn, is derived from the paraffin hexane, by the displacement of six of the hydrogen atoms, one from each carbon atom, by the radiclc (oh). glucose bears to mannitol the relation of aldehyde to alcohol, but the aldehydic properties are so feebly displayed that chemists have always dubbed it an aldehyde with hesitation. one peculiarity of glucose is the ease with which it is etherified. when it is dissolved in methylic alcohol, and the solution is slightly acidified with hydrogen chloride, it is soon converted into a mixture of products chief of which are two monomethylic derivatives—a- and #-methoglucoside, cl] uos(ochs). in neither of these is the slightest trace of aldehydic behaviour to be found. a (third) y-glucoside isomeric with the a and 8 forms has also been isolated, which is chemically a far more active substance, a solution of glucose appears to contain but a minute proportion at most of this form, and consists mainly of the a and @ forms in equiltbrium. chemists are now of opinion that the glucoses and these glucosides are closed systems, analogous to that of phene (ben- zene), but saturated. phene itself may be converted into a saturated system, cehie (hexahydrobenzene or hexamethylene), which jis scarcely distinguishable chemically from the parafhn hexane. h, he cas : hcc dekh c=c h, he chemistry a hexhydric alcohol, cshe(oh)., derived from this hydrocarbon, is a natural product. being closed systems derived from phene, but saturated like methane and its substitution derivatives, such compounds are conveniently spoken of as phanes. phanes.—a simple and rational formal expression of the pe- culiar behaviour of glucose, and especially of the methogluco- sides, is given if it be assumed that they are oxophanes, phanes in which several atoms of carbon are linked in a closed system by means of an oxygen atom. if so, one end of the paraffinic chain of mannitol becomes, as it were, soldered to a link along the chain, when, by hydroxylation, the terminal carbon atom is converted into the aldehydrol and a molecule of hydrone is thereupon withdrawn from the compound. to what “ hnk” down the chain is the terminal atom thus united? the problem has given rise to a large amount of work and an equal amount of speculation, extending over years—we are not yet satisfed that the solution is in our hands. the most probable ‘“‘ inter- pretation ” of the character of glucose and the glucosides, how- ever, is now thought to be that given by the assumption that they are phanoids: that a- and 6-glucose and the corresponding glucosides—are hexaphanes (hexoxophanes) and +y-glucose and the y glucosides pentaphanes (pentoxophanes). ho-hc—ch-0oh ho-hc-—ch-oh | | ho-hc ch-ch,0h ho-hc ch-ch(oh):-ch2oh | : de ho-hc—o o a and y assuming such to be the case, what is mannitol—is it truly paraffinic or is it potentially phanoid? c—c he \ g cc £ nf when hexane is gradually hydroxylised, does the carbon chain remain essentially a straight one, like a billiard cue, or does it bend? if the latter, when is the ‘‘ screw ”’ put on? this is an in- quiry into the art of the chemical stevedore which the x-ray analysts must help to solve. whenever it occurs, the “‘ bending ” is doubtless a necessary consequence of the loading of the molecule with oxygen and the attraction which oxygen has for oxygen. it may be added that although the formulae are written as ‘rings’: actually in the model the carbon atoms are close packed either in clumps or in closed systems. four and five may be united by an atom of oxygen, but the minimum number of carbon atoms in a closed system is probably six. returning now to the consideration of the manner in which carbohydrates are formed mm the plant, it may be pointed out that although glucose is the fundamental carbohydrate unit, the opinion prevails, at the moment, that cane sugar, not glucose, is the primary product; starch may also be a primary product, but, as it is scarcely present in the leaves of monocotyledons, it is no longer supposed, as it once was, that this is ‘ke one and only initial product of assimilation. in any case, the carbohydrates should be regarded as immediate primary products of solar activity, if built up, as such, from carbonic acid, as this is reduced under the immediate influence of chlorophyll. if formed from formaldehydrol first sct free in the cell fluid they are but sec- ondary products. the fact remains that in some plants the chloroplasts become laden with starch; in others, in’ which cane sugar rather than starch seems to function as reserve material, they do not. yet in these latter, if the concentration of the sugar within the leaf be raised by dipping the cut end into a strong solution of sugar, their chloroplasts equally become laden with starch. apparently, in monocotyledons, the conditions of concentration are not normally those required for the production of starch; or maybe they are such that the starch is no sooner formed than it is hydrolysed and passes out as a lower sugar. the more probable explanation seems to be that the units as- a ee ee 597 sembled upon the template are tied together perhaps only in pairs and that these float away. dilution would operate against continued linking up of molecules. the essential carbohydrates are certainly glucose and fructose, cane sugar, starch, inulin and cellulose. whilst cane sugar is compounded of glucose and fructose, inulin is composed of fructose, starch and cellulose, being formed of glucose alone. the units are differently arranged and in diflerent numbers in the higher sugars, in unknown numbers in inulin, starch and cellulose. the difficulty of dealing with starch is enhanced by recent discoveries: that what is commonly called starch is not a single substance, and that, apparently, a single layer in a granule may be a mixture of “ starches.”” though starch and cellulose are ultimately resolved by hydrolysis into the same glucose, diverse products are obtained on the way—the one yielding maltose, the other cellobiose, both isomerides of cane sugar. the relation of these three, however, is simple, as fructose, which is associated with glucose in cane sugar, is but glucose slightly modified, and the other two are perhaps respectively a and § glucosides corresponding to the a- and $-methoglucoside already con- sidered, the difference between these being simply that the methyl group is attached in one or other of the two possible positions to the carbon atom vrext to the oxygen link in the oxophane. there is still much uncertainty on these points. taking all the peculiarities into account, which are thus apparent, it is clear that the formation of sugar is a directed process from the be- ginning—that the sugars are all, as it were, formed against tem- plates or patterns present in the plant cell. whether formal- dehydrol be produced and sent into circulation, or whether it be directly laid down to one or other carbohydrate, matters litthe— the primary elements are ultimately arranged and linked up in definite ways. the pattern cannot well be other than the thing itself. cane sugar, however, being an intensely soluble material, cannot be thought of as acting as such. yet it is not difficult to picture molecules of cane sugar being built into the protoplasmic structure of the chloroplast and the assembly, at such centres, either of formaldehyde or of glycerose molecules, which there- upon interact and give rise to cane sugar itself. but how? some mechanism must be imagined to tie the threads (oh-+oh) and cut off the spare ends (as oh.) in the way previously considered. formaldehydrol and the sugars are in themselves inert—they are not clectrolytes. they must be made into electrolytic con- ductors, by means of acid or alkah, before they will act together or give way to attack. we know that, in the fermentation proc- ess, glucose is first associated with a phosphate. we know that in the plant phosphate plays a determining part. it is not going far to assume that phosphate comes into play in the formation of carbohydrate: how exactly, whether in the shape of a floating mechanism—such as an enzyme—or as a molecule held in the protoplasmic complex, much as the crane is now placed on a building in course of erection, it is impossible to say. that the phenomena are of suchan order would seem to be highly probable. away from the leaf, leucoplasts are met with in which transi- tory starch is often found, so that the enzymic mechanisms would seem to be widely distributed. these mechanisms are clearly things apart—little factories in which special operations are carried on. for example, in sorrel, which is a strongly acid plant, the chloroplasts in the leaf are to be seen tucked away, as it were, in corners of the cells and are clearly independent of the acid in the fluid in which they float, their lining membrane being impervious to acid; for if this mem- brane be broken down by exposing the leaf to chloroform, at once the chlorophyll is changed in appearance. normally, it would seem, sugar must be able to pass out, although acid cannot pass in—but sugar is not an electrolyte. such observations are the 598 clearest possible evidence that the reduction of carbonic acid takes place within the chloroplast: that the formation of carbo- hydrate is effected under its influence would also seem to be open to little doubt. in the starch granule, there seem even to be traces left, between “ the starch molecules,” of the erecting mechanism. we have yet to learn whether the silica in the cereal stem be not such a survival, not a mere strengthening inclusion. constructive afetabolism.— having made sugar, the plant pro- ceeds to use it in its many wondrous feats of constructive metabolism. the micro-organism—the yeasts and all unicellular organisms—we know is able from sugar alone as organic pabulum, with the aid of a few mineral salts, to reproduce itself to an un- limited extent. raulin’s nutrient solution, much used by pas- teur, was composed as follows:— water . 1,500 carbonate of magnesia 0-4 sugar candy 70 sulphate of ammonia . 0-25 tartaric acid . 4 sulphate of zinc . 0:07 nitrate of ammonia 4 sulphate of iron . 0:07 phosphate of ammonia 0-6 silicate of potassium . 0-07 carbonate of potassium 0-6 apart from the singular power possessed by the higher plants, with the aid of chlorophyll, of reducing carbonic acid and of meeting the many requirements of cells of different orders, the chemical functions of unicellular and multicellular organisms would seem to be similar. when the compounds other than sugar present in the plant and more particularly in the animal, in which sugars play a very minor constructive part, serving mainly as fuel, are considered, it is obvious that they all contain very much smaller proportions of oxygen than the sugars. the life of the plant is essentially a reductive process—as indeed it is in the beginning, as the evolution of oxygen is but an accident of the reduction of carbonic acid by means of hydrogen derived from hydrone, the oxygen being cast aside as a by-product of no account to the plant. we have to explain the constant with- drawal of oxygen. only one agent is at disposal for the purpose ——-that used in the first act: hydrone. we have to account for the disposal of its oxygen—without further direct assistance from the sun. inasmuch, however, as starch contains about half the energy the carbon and hydrogen that are in it would furnish if burnt alone, the plant actually continues to work even in the dark with energy derived from the sun, the more as it also makes use of oxygen. whatever the carbohydrate reserve material, it is brought down to a hexose, chiefly glucose, for use. experi- mental evidence favours the view that glucose first undergoes resolution, by hydrolysis, into two molecules of glycerose. this seems the first stage in alcoholic fermentation under the in- fluence of the complex enzymic mechanism in yeast (zymose). ae ciloh | es asec ie = 2 ne ho-hc—o ciw(oh)2 it is noteworthy that the presence of phosphate is essential, and that, in a preliminary stage, the phosphate and hexose interact. the argument has already been put forward but may be re- peated, that, in the converse process, in the plant, phosphate is also operative and that this is an indication of at least one reason why phosphate is essential for plant growth. the reason why phosphate is essential is perhaps not far to seek. glucose by it- self, in aqueous solution, is not an electrolyte and, therefore, should not be open to attack—by the introduction of an acidic racdicle into its structure, it becomes an electrolyte and can there- fore be included in a circuit of change. the two isomeric trioses, glyceraldose and glyceroketose, like the two isomeric hexoses, glucose and fructose, are mutually interconvertible—under the influence of a trace of alkali. the process is probably of the following order:— ch,-oh ies ch.-oh | | fee = c-oh+or, = c(oh)e ch-oh-oh ch:-oh ch; oh chemistry this change takes place rapidly and, when equilibrium 1s at- tained, both compounds are present in large proportions. glucose is only very partially changed into fructose and the reverse, by a similar isomeric change. in the fermentation process, this type of change is carried a stage further, apparently under enzymic influence, though it can be effected with the aid of alkali:— — ch ch; | | — — pee <; c(oh): ch(oh), ch(ot), ch(oh). the compound thus produced (pyruvic aldehydrol) is eminently oxidisable and easily oxidised to pyruvic acid—ch3-co-co (oh). it is thought that this acidis formed and, by hydrolysis, re- solved into aldehyde and carbonic acid—ch;3:co(oh)+oh2= ch3-coh+co:+-oh2. it is known that yeast contains a peculiar enzyme, carboxylase, which will effect this change. also, that if the fermentation be carried out in presence of a sulphite, alde- hyde may be obtained in large quantity, in place of ethylic alcohol. further, if the liquid be maintained alkaline, much of the glyceraldose (ketose) escapes oxidation and is reduced to glycerol—which is but a very minor product of fermentation under ordinary conditions. it is thus seen how the glycerol of fats may be produced. the production of alcohol in the fermentation process may be regarded as one in which two separate molecules are concerned and reciprocally hydrolysed in circuit, the one being hydrogenised, the other hydroxylised:— the ordinary hydrolysis of cane sugar may be regarded as a change of this order but one in which two separate halves of the molecule are affected, the one being hydrogenised, the other hydroxylised. to bring the two processes into complete agreement, proof is required of some mechanism in the fermentative process, where- by the two aldehyde molecules are assembled in circuit with hy- drone. possibly, only suitable determining conditions of acidity and concentration are necessary—no special catalyst. it is possible to ferment sugar in a variety of ways. thus, from it may be produced normal butylic alcohol and acctone, in- stead of ethylic alcohol. it is not difficult to explain the process. aldehyde is easily condensed in the following manner:— ch;:ch-oh-oh+ch;-ch(oh).= ch,:-ch(oqh):-ch-ch(oh)+0oh2 this compound is convertible, by direct reduction, into normal butylic alcohol, whilst on oxidation it gives acetoacetic act:, ch;:co-ch.co-oh, which is easily resolved into acetone and carbonic acid. it is not diflicult to visualise the formation of com- plex fatty acids as a consequence of continued condensation and reduction, accompanied by the necessary amount of hydroxyla- tion to form the necessary hydrogen. proteins.—the origin of proteins is to be sought in this same direction. it is known that these are but collocations of simple molecules, formed by condensation of molecule upon molecule, a great variety of molecules being thus linked together. the units range from amino-acctic acid, ch(n hy)-co-oh upwards, as shown in the following table. glycine cliz(nh2), cooh alanine chs-ch(nh.)-cooi! valine (ch3)2:ch-ch(nh2) cooh leucine (ch3)2:ch-ch2-ch(nh»)-cooh isoleucine (ch3)(coh;) >ch-ch (nit) -cooh serine cihloh-ch(nh,z)-cooh lysine h,.n-ch2,cilch2ch (nh) cooh nh#l, arginine iin = me nh-ch2-ch2-ch2zch(nh:):-cooh chs-chom):+ 55 aa chemistry phenylalanine csh;-ch2-ci1(nh2)-cooh tyrosine ho-c.h4-chechi(n h.)-cooh aspartic acid hooc-ch,-ch (nh2)-cooh glutamic acid hooc-ch,.-ch.-ch(nh,) cooh hydroxyglutamic acid hooc-ch2-choh-cii(nh:2)-cooh cystine iooc-ch(nh,2)-ch:s—sc h2:ch(nh:)- cooh proline chz—ch; | ch, cli-cooh boa nei hydroxyproline ho-ch—ch), | cll, ch-cooh bed nil histidine ch a ne. a el | | he =c—ciih-ch(nh,}-coom tryptophane c—cll2-ch (nie) -cooh \ c,h, ch hues nil the production of such amino-acids is to be accounted for without much difficulty, bearing in mind what is said above, of the manner in which hydroxy-(keto) acids, such as pyruvic acid, are formed in the fermentation process and the readiness with which these are attacked by ammonia:— ch,-c(oh)co-oh-+nh;=cil;-c(oh)-(nh,)-co-oh + 11.0 such acid, on reduction, is converted into aminopropionic acid or alamine, a constituent of many proteins. aminoacetic acid (glycine) is conceivably derived in a similar way from glyoxylic acid, ch(ohd)..co-oh this being one of the normal oxidation products of glycerose. the only series of compounds present in plants of which the origin is at present obscure are the phenoid derivatives, phenyl- alanine, tryptophane and tyrosine, which are present in most of the proteins. broadly speaking, however, it is clear that they are formed from simple materials by condensation processes such as those explained. as to the structure of the proteins, we have no conception, at present, whether their molecules are long-drawn-out systems like those of the fatty acids or compressed like the saccharons. the latter is the more probable. regarding them as forming sheets of a pavement-like character, it is possible to conceive the arrangement of the several units upon pre-existent molecules of the protein and the consequent determination of the order of arrangement. without some such interpretation, it is impossible to explain the persistence of particular proteins in particular materials of either animal or vegetable origin. nitrogen absorption—dplants of non-leguminous orders ap- parently derive their nitrogen, at least for the most part, from ammonia in the soil. nitrate, we know, passes into the plant and may even be stored in the cells in considerable amounts. nitrates are not easily reduced, however. still, proof has yct to be given that they are directly utilised by the plant. the re- markable direct absorption of nitrogen by organisms in the soil and by others living in the nodular growths found especially upon the roots of leguminous plants is in no way understood at present. probably, it is to be associated with the occurrence of intense oxidative changes, which make hydrogen disposable at a high potential. the absorption of so inert a material appears to be less remarkable than it did, now that vast quantities of ammonia are produced by the direct interaction of hydrogen and nitrogen under the influence of a catalyst—but this is effected at a high temperature and under 4 high pressure not within the cold soil. strangely enough, the production of ammonia by direct reduc- tion of nitrogen has never yet been observed under ordinary simple laboratory conditions. methyl alcohol —a- reference may be interposed to modern synthetic methods of producing organic materials which may well 599 put fermentation processes and natural sources into the shade. methylic alcohol has long been produced as a by-product in the manufacture of charcoal—formerly much used for gunpowder. formaldehyde, which has been greatly in demand of late years, has been prepared by oxidising such alcohol. it has recently been shown that, in presence of a suitable catalyst, under appropriate conditions of temperature and pressure, carbonic oxide and hydrogen interact directly and may be converted all but completely into methylic alcohol. at higher pressures the product is more complex, and apparently a whole series of paraffinic alcohols may be produced. clearly, it isa case in which formaldehyde molecules are formed and brought into interaction and condensed, as they arein the plant, the product being, how- ever, at once reduced. | oxidation.—in the animal, oxidation is at the root of muscular activity. the extent to which it is effected as an independent process is not clear but, at least, the fats must be primarily oxidised to some extent before they are rendered available for the purposes of muscular activity. oxygen is so essential to plant life that the gas must take part in its vital activity, but it is in no way clear what special function oxygen subserves. many organisms can live without air, the yeasts all do; oxygen becomes necessary, however, at the reproductive stage, though only in minimal amount. aerobic organisms use up a large amount of oxygen. in the animal, oxygen is stored in haemoglobin as oxyhaemoglobin and thence passes into solution as required, a definite equilibrium being maintained between the oxygen within the red-blood corpuscles and the solution without the cell. oxy- haemoglobin itself, apparently, has no action as an oxidising agent. at root, the oxidation (hydroxylation) process in plant and animal is alike in its nature, it may be supposed. usually, if not always, a catalyst as well as a determinant, is involved in the change—the oxidising catalysts are known generally as oxidases. these have been classed as enzymes, but modern work is tending more and more to show that, though they may differ and be limited in their range of activity, they are not enzymes in the sense of being selective agents, in some way structurally related to the compounds they affect. the enzymes, as a class, are apparently all hydrolytic agents; at least, it may be desirable to confine the use of the term to agents exercising this function alone. thanks to the refined work of fletcher, hill and hopkins in particular, it is now clear that the act of muscular contraction derives its energy from an essentially enzymic process, akin to that of fermentation, whereby hexose (glucose) is converted into lactic acid, ch;-ch(oh)-co-oh—only then does oxygen be- come directly operative. it may well be that the lactic acid is merely hydroxylated and that the product, ch3:c(oh)2co-ol,, is resolved into carbon dioxide and, a residue which is rebuilt to hexose. in this connection, it may be well to discuss more closely the phenomena of oxidation in general. it may be submitted that not only, as already stated, (1) is oxidation primarily, in so far as the oxidised compound is concerned, a process of hydroxyla- tion, but (2) that oxygen or whatever oxidising agent be used 1s active only indirectly—as depolariser and adjuvant in an elec- trolytic circuit. the oxidation of hydrogen has already been formulated from this point of view, thus:— fh 1c. 6 sraeearee cl o- 2h.0+ho-oil h ho +.2. 4 o note.—dots are used here and elsewhere to indicate the electro- lyte of which iio and h are the terminals. whereas hydrogen and oxygen interact readily, at the surface of a platinum plate (in presence of the necessary determinant), a mixture of carbonic oxide and oxygen not only remains una ffect- ed but, if carbonic oxide be added to the mixture of oxygen and hydrogen, it actually inhibits their interaction, under the in- fluence of platinum. | carbonic oxide and hydrogen have very nearly the same heats of combustion, that of hydrogen (to liquid water) being slightly 600 above, that of carbonic oxide, slightly below, 68,000 units. it may be suggested that 68,000 is a limiting value and that no interaction in which a less amount of energy is developed will take place directly—without an adjuvant or depolariser. this seems to be an immediate corollary to the view, that as the action is electrolytic the determinant is necessarily liquid and composed of water and a salt. carbonic oxide should be incombustible in the absence of a depolariser, if this view hold good, as water must be electrolysed in the circuit of change. the fact that it explodes when moist may be accounted for by the assumption that the spark or flame applied to the mixture causes the production or introduction of a slight amount of hy- drogen, which is burnt along with it, a supply of hydrogen being kept up by a slight decomposition of water in the wave front as the explosion spreads. prof. bone has found that the mixture be- comes less and less easily exploded, requiring ithe application of a greater and greater intensity of current to force a discharge across the sparking gap, as the drying is more and more com- plete. using phosphoric anhydride as drying agent, a limit is reached but only after several months. explosion ultimately takes place but only when a very powerful electro-motive force is applied and is attended with a most brilliant flash of light, but the interaction is far from complete. what is the explana- tion of this behaviour? it may be either a case in which a sufficient amount of the electrolytic determinant is expelled from the platinum wire clectrodes by the discharges in the form of previously imprisoned hydrogen molecules and “ splut- tered ’’ platinum motes, or one in which the gas is dissociated inte its elements and the released carbon is exploded in stutx nascendi under the influence of the traces of determinant liberated from the sparking wires and the walls of the vessel. there is urgent need to consider problems of this kind, in view of the importance attached to the discharge of electricity through gases by physicists, who are paying no attention whatever to the purity of the materials and the possible variation in the system through which the discharge is passed. carbonic oxide is perhaps the most interesting of all oxidisable gases. it needs little drying to render it incombustible, and its combustibility grows as the amount of moisture present is in- creased over a considerable range. the probable explanation of this behaviour is that it is hydroxylised, not as such but indirectly through the determinant which becomes associated h , being of a very low order of | oh stability, would necessarily be in very small proportion unless a considerable proportion of hydrone molecules were present. its condition is comparable with that of a very weak acid in solution. the influence of hydrogen and of hydrocarbon in promoting the combustion, when present together with the gas, may be ascribed to the initial formation of perhydrone from the hydro- gen, which then functions as active depolariser in the carbonic oxide circuit. al ho... ho oul _ co 4- + | = coc +ohs+ | -+2h20 nou ho...h ho ou va in other words, carbonic oxide, in reality, is burnt at the expense of pre-existent perhydrone, not in any “ direct’ way, at the expense of oxygen. in most cases of oxidation under laboratory conditions, the agents used are salts and therefore electrolytes. the only agents which are not are perhydrone and oxygen (or ozone) itself, there is much evidence to show that these are inert in themselves; they need the aid of a determinant. thus, to make perhydrone effective, it is commonly associated with ferrous sulphate and 503h va 3 with it. the compound cog is probably active as the perhydrol ee , an electrolyte. 0-0h the oxidases, to which reference has been made, seem to be, in the main, colloid catalysts—substances which are reversibly hydroxvlisable and convertible into perhydrols. some are un- | chemistry doubtedly iron or manganese compounds. apparently, the activ- ity of these is largely dependent upon the effective acidity of the media in which they are placed, and they are mostly active only if it be near to the point of neutrality. control of oxidation.—warm-blooded animals are gifted witha remarkably efficient heat-controlling mechanism. considering the high average temperature of the blood and the amount of easily oxidisable material available, it is probable that without such control temperature would rapidly rise to ‘ impossible ”’ heights, as in fever. the question may be put: to what extent, if at all, is any chemical control exercised? it is only during recent years that special attention has been called—particularly by moureu and dufraisse—to the way in which an oxidation may be antagonised and potential oxidation prevented by the pres- ence of a second oxidisable substance. the aldehyde acrolein, ch2:ch-cho, a highly volatile, tear-exciting liquid, 1s extraor- dinarily sensitive to oxidation; it soon becomes acid and then rapidly passes over into a hard, resinous condensation product. this and similar changes are prevented by a whole series of oxidisable substances—phenol, quinol, pyrogallol, even by po- tassium iodide, only a minute proportion of the antagonising agent being necessary. many such instances are known. phosphorus does not glow in the presence of a trace of volatile oil. solutions of ferrous sulphate and of alkaline sulphite, taken separately, are easily oxidised by air: in admixture, they are not. perhaps the most remarkable case is that already referred to—the prevention of the interaction of hydrogen and oxygen at a platinum surface by carbonic oxide, which itself is not oxidisable at such a surface, however. it may well be that such antagonisms play a determining part, at least at times, in the economy of animal and plant hie. poisoning by hydrogen cyanide has long been thought to be a consequence of the inhibiting effect on oxidation which it exer- cises at certain nerve centres. it at once puts a stop to the evolu- tion of oxygen from perhydrone by yeast and also by finely divided platinum. arsenic may perhaps have a similar influence. it is conceivable that the intense poisonous activity of some alka- loids may be of a similar order: it cannot be a mass eflect, the quantity required is so minute. the nearest explanation of such antagonistic action would seem to be that the oxidisable ma- terials in competition are ‘‘ reversibly ”’ oxidised and converted into “ perhydrols,’’ which in turn interact, reproducing oxygen and the original substances. such matters are assuming great technical importance in connection with the internal combustion engine, using vaporised liquid fuel (see internal combustion engine). the various petrols differ greatly in explosive behaviour—in the rapidity with which they are “ burnt.” the most successful regulative agent hitherto used has been lead tetrethide, pb(c2hs)s. it would seem likely that the effect this exercises—whatever its precise nature—must depend upon the lead functioning as an oxidising ‘‘ catalyst.” lastly, we are becoming more and more alive to the fact that life is regulated by a number of mysterious secretions from special glands, in different parts of the body—the pituitary, the thy- roid, etc. (see endocrinology). our vegetable food is proved to contain accessory factors or adjutants, in minute amount, in absence of which nutrition breaks down (see vitamins). another case in point is insulin (q¢.v.), a characteristic pan- creatic secretion but of frequent occurrence in animal tissues and apparently also in yeast. hf used in very small amount, this material makes good the disturbance in function, whatever it may be, from which diabetics suffer; actually, it causes the dis- appearance of glucose from the blood. such agents are all active in very minute amount and their effect would appear to be regulative. one of the most striking cases yet brought forward is the apparent need of a most minute, indeed altogether in- finitesimal, amount of borate by the nodules which form on ihe roots of leguminous plants. unless borate be present, the nodular organisms are not brought into effective, reciprocal relationship with and fed by the plant. chequers the chapter is one of infinite importance in its vital connection but scarcely entered upon as yet, especially on the theoretical side. the colloid nature of natural products-——apart from the compounds dissolved in the cell fluid and certain reserve ma- terials (the simpler sugars), the components of animal and plant structure are all highly complex, slightly soluble, if not insoluble materials—proteins for the most part. the term colloid (q.v.) was early applied to them by graham, because of their glue- like character. it is to be deplored that the term has been widened and applied generally to finely divided materials in suspension in liquid media—still more that a bastard, hybrid nomenclature has been developed which successfully serves but to obscure the obscure. as jacques loeb has shown, when the proteins are fairly considered from a chemical standpoint, they are as other compounds in general behaviour. thus far, the phenomena of solubility have been dealt with in the vaguest possible manner; structural considerations have scarcely if at all been taken into account. solid paraffin is not even wetted by water: the hydrogen in it would appear to be unattractive and in the “ saturated state ”’ in which the carbon is present, this also, apparently, has no residual affinity to water. yet the molecules are not without residual affinity. sir william bragg’s x-ray measurements show that when paraflin is fused upon glass and then cooled, the molecules become ranged like scaffold poles side by side, and these interlocked poles become erect and ranged in rows. when the terminal group is oxidised and the paraffin is converted into stearic acid, it is wetted by water but only at the carboxylic tip: in other words, it is soluble at the tip but not as a whole. the higher fatty acids form such films upon water, the molecules standing upright, side by side, the carboxylic tips resting upon the liquid. the paraffins are efficient lubricants, because they are so slightly attracted to solid surfaces. all other fluids are more or less ‘“‘ held” by the surface, their “ grip’ depending upon the nature of the surface and the character of the material; this is clearly a function of structure, and the effect would seem to be exercised at and upon the centres of residual affinity in the molecules. it would seem to be permissible and rational to extend this point of view to substances in solution. difficult as it may be to define the term solubility and confine its use, it were time that we had some definite conception of the nature of the reciprecal relationship of solvent to “ dissolved ”’ substance. in view of what is said above, stearic and oleic acid may be said to be in solution only at the carboxylic tip. when the alkali-metal salts of these acids (soaps) are dissolved in water, again only the car- boxylic tip is in solution; definite reciprocal relations are estab- lished between it and the near-by water molecules, but the rest of the molecule is to be thought of as merely making a hole in the water, as it were. hence, perhaps, we may arrive at a distinction between dissolved and undissolved substance and picture this as, in a measure, analogous to that to be drawn between airship and balloon. the balloon but makes a hole in the air. it is a mere floating body, itself mechanically inert but knocked about by the impacts of the air molecules. so is the body of the airship—like the balloon, it merely makes a hole in the air. in virtue of the engine and propeller, however, as the propeller grips the air, the airship is brought into more active relationship with the air; at icast, it has a directing mechanism, though, as in the balloon, the interaction between ship and air is purely kinetic—no selective affinity of any kind comes into play. a neutral particle—if there be such—suspended in a fluid may be pictured as in the condition of the balloon; under the micro- scope, the particles are seen to be in rapid movement (brownian motion), due apparently to their bombardment by the active unit-molecules within the hquid. perhaps the only strictly neutral particle conceivable is that of a paraflin—all other ma- terials seem to be possessed of some clegree of surface attraction, to display some affection for fluid molecules in general. the airship, however, 1s the analogue of nearly all organic molecules more or less soluble in water. there is an all but oo! insoluble body, often very large, which is associated with a radicle more or less avid of water. alcohol is a derivative on the one hand of the hydrocarbon ethane c,ii¢, which is insoluble in water; on the other hand, of hydrone, being formed by the with- drawal of an atom of hydrogen from each and the fusion of the residues. it is miscible with water in all proportions—such is the avidity of the residual oh for water. none the less the ethane residue is to be thought of as but dragged under by the associated oxygen. benzene, cshs, spreads out as a layer upon water and is practically insoluble; phenol, cshs-oh, is but mod- erately soluble; the sulphonic acid, colts-sosh, formed by the interaction of benzene and sulphuric acid, is intensely soluble. a large class of dyestuffs, the direct cotton dyestuffs, is formed from benzidine, n e2:celiy-cel i: nh, an insoluble material, bv coupling it through the agency of the nhe groups with certain more or less complex sulphonic acids. congo-red is one of these. +nh2 nee-+ > n-nh-colls-colfa: nhn: —hsos sosh— the slight “solubility ” of this huge molecule may be ascribecl to the two primary so3h groups. as a matter of fact, there is reason to believe that the dissolving intluence this group usually exercises is greatly lowered in amino-compounds of the type shown by the “ control’ exercised by the basic nitrogen atom. the lower sugars are easily soluble—cane sugar liquefies in one- third of its weight of water. as already explained, in these each carbon atom carries an oxygen atom and the oxygen atoms undoubtedly are centres of attraction for “‘ water.”? as complex- ity grows, the sugars become less soluble and starch is practically insoluble; in some way, the residual affinity of the oxygen atoms becomes lowered. starch, however, is a typical colloid when properly distributed in water. the proteins are equally so. in these the centres of attraction are cither oxygen or nitrogen, ancl such centres are frequently repeated. such colloids may be pictured as having “ water ” collected about them at the various active centres. they are “ held up,” as it were, by these in the liquid. only compounds of this type deserve the name of colloids. if such be a true picture, we cannot well say where dissolution begins and where it ends; the passage from soluble to insoluble must be continuous. degree of solubility must be a question of relative affinity, as between the molccules of solute, between the molecules of solvent and between the molecules of solvent and solute, that of the molecules of solute being more and more easily overcome, the greater the attraction exercised by the molecules of solvent. from this point of view, the plasticity of clay is practically the ‘ plasticity ” of thin films of water. very finely divided (deflocculated) particles of clay, in an alkaline medium, may be pictured as the condition of soap molecules swimming in water; if the medium be made acid, in either case, molecules are formed which have less affinity for water and, therefore, tend to aggregate. finely suspended matter may be of three kinds: acid, alkaline or neutral. neutral particles show no tendency to wander to either electrode in an electrolytic ficld; the acid form wanders to one electrode, the alkaline to the other, and in this behaviour we may have before us what may be visualised as happening to dissolved (potential) electrolytes. ch ban.) chequers.—chequers court, buckinghamshire, a typical e:nglish country home of the early renaissance period, became an official residence of british prime ministers in 1921. it is situated in a beautiful part of buckinghamshire, not far from princes risborough and 38 m. from london. the house and estate, about 31,500 ac. in extent, with adequate means for maintaining them, were generously put in trust for this purpose by their owners, lord and lady lee of fareham. here caractacus had a stronghold, of which the earthworks are still visible. ‘‘ radulphus,”’ clerk to the exchequer, was 602 owner under henry ii., and the place appears to have taken its name from his office. here, in 1565, his descendant, william hawtrey, remodelled the house of his ancestors and gave it much of its present character and appearance. here in the 18th century, came, and still remains, a unique collection of crom- well portraits and other relics, the russells, who had inherited the estate, being descended from one of the protector’s daugh- ters. the russells maintained the elizabethan house with hitle alteration, but robert greenhill, who inherited from them early in the roth century, plastered the whole of the outside and redecorated the interior in strawberry hill gothic fashion. when the lees entered on a long tenancy in 1909 they sought to reveal all the remaining ancient features, and to introduce others characteristic of the days of the hawtreys and the rus- sells. their activities covered not only the interior and exterior of the house, but its immediate environment, forecourt and for- mal gardens with due architectural features completing the pic- ture. to much that was interesting in the way of pictures, books and furniture belonging to the house, a great deal of fine quality was added, and thus chequers became one of the most beautiful and complete expressions of the historic english country house. in 1917 lord and lady lee changed their tenancy into a free- hold, and proceeded to create a trust, which, on their deaths should make the house an adequate seat where the prime min- isters could entertain guests. the original draft for the chequers trust declared that:— the main features of the scheme are, therefore, designed not merely to make chequers available as the official country residence of the prime minister of the day, but to tempt him to visit it regular- ly, and to make it possible for him to live there, even if his income should be limited to his salary. with this object a sufficient endow- ment is provided to cover the cost of a permanent nucleus staff of servants, of keeping up the gardens and grounds, of maintenance and repairs, and other necessary outgoings. there is also a residential allowance for the official occupant calculated in a fashion deliberately designed to encourage regular week-end visits. the draft, however, insisted upon the unaltered preservation of both house and contents:— another cardinal object of the scheme is to preserve, so far as possible, the main architectural and archacological features of the house and surroundings in their present restored condition. it will, therefore, be provided andl strictly enjoined in the trust deed that no alteration, mutilation, addition or subtraction shall be made to the principal features of the house. in 1920 lord and lady lee resolved that this generous scheme should not await their demise but should take immediate effect. all the preparations for establishing and working the trust hav- ing been completed by the end of that year, mr. lloyd george, then prime minister, held his house-warming on jan. 8 1921. after that date mr. lloyd george and his successors, mr. bonar law, mr. stanley baldwin, mr. ramsay macdonald, and mr. baldwin again spent part of their time here during their respec- tive terms of office. (h. a. t.) cheque writer: sce office appliances. chess (see 6.93)}.—chess has gained very considerably in popularity since 1910, and especially since the conclusion of the world war. during the war, tournaments were promoted and financed by local authorities at hastings, scarborough, weston- super-mare, stratford-on-avon and other places in england; and at san sebastian, scheveningen, carlsbad, baden-baden, mari- enbad and several other resorts on the european continent. although no international contests were held during the war, 18 first-class international tournaments were played in different parts of europe and america between r1g10 and 1925. the principal events were:—san sebastian, 1911 and 1912, the first won by j. r. capablanca, and the second by a. rubinstein; petrograd, 1914, first e. lasker, second capablanca, third a. alekhine; london, 1922, first capablanca, second alekhine, third milan vidmar of yugoslavia; and new york, 1924, first lasker, second capablanca, third alekhine. in the tournaments mentioned only three new players came to the fore, namely, alexander alekhine, of moscow; e. d. bogol- juboff of ukraine; and richard reti of czechoslovakia. alekhine won several first prizes in compctitions only slightly less impor- cheque writer—chetwode tant than the petrograd, london and new york tournaments. he established a record for blindfold play, by playing 28 games simultaneously sans voiy in paris. bogoljuboft’s best performance until 1926 was winning the first prize in a strong tournament at breslau in 1925. reti, a strong original expert, won some notable honours. at geteborg in 1920 he won the first prize from rubinstein and bogoljuboff, and at the new york mecting in 1924 he was the only competitor who won a game from capablanca. an expert blindfold player, he became the leader of a new school, and published a book, afodern ideas in chess. honourable mention should be made of sir george thomas, bart. and f. d. yates, england; max euwe, holland; f. samisch, germany; and the clever mexican plaver, c. torre. after many years of negotiation a match for the world’s championship was contested at havana in 1921 between lasker and capablanca. the result was disappointing. the conditions stipulated for 24 games, but after the fourteenth game, with the score capablanca 4, drawn 10, lasker o, lasker resigned the match and the chess championship of the world. an inter- national masters’ tournament was held at moscow in dec. 1925, being subsidised by the russian govt. to the extent of about £3,000. the competitors included the champion, capa- blanca; the ex-champion, lasker; the united states champion, f, j. marshall; also rubinstein, reti, tartakover, torre, several very strong russian players, and last, though by no means least, bogoljuboff who, despite the fact that he was beaten by capa- blanca and drew only with lasker, nevertheless won the first prize, with a score of 153 points out of a possible 20. in great britain excellent work has been done by the british chess fed- eration, the organisers and managers of the london inter- national congress, 1922, and of the annual national chess congresses. afethods of play.—no vital changes in the actual playing of chess since 1910 can be recorded. a slight alteration in the technique of opening games has been observed, though none of it is new. the development, for example, of the king’s bishop, at k ktz2, instead of at q3, in the queen’s pawn game, is, at least, as old as the days of blackburne and steinitz. the selec- tion of kt to kb3 for the first move was consistently practised by zukertort, in the london tournament of 1883. “ reti’s open- ing” (l.at. to kb3, p to q4, 2.p to qb4) is an unimportant deviation of the customary development of the queen’s pawn game. finally, there is the so-called “‘ alekhine’s defence ” (p to k4, kt to kb3), first adopted by alekhine in a tournament at budapest in 1921, but, as a matter of fact, often played in london before alekhine was born. the games played for the world’s championship in 1921 appear only slightly different from those contested between lasker and steinitz in the world’s championship match of 1893. bibliography.—j. r. capablanca, chess fundamentals (1921); e. lasker, afetn wettkampf mit capablanca (1922); l. ht. dawson, a short guide to chess (1923); a. emery, chess openings (1923) and chess of to-day (1924); rk. reti, modern ideas in chess (1923), trans- lated by john hart; j. du mont, the elements af chess (1925); i’. j. marshall and j. c. h. macbeth, chess step by step (1925). (l. van v.) chetwode, sir philip walhouse (1869- ), british soldier, was born sept. 21 1869, and in nov. 1889 was com- missioned to the roth hussars from the militia. he saw active service in burma and south africa, and later became assistant military secretary to sir john french at aldershot. promoted to the command of the 5th cavalry brigade in may 1014, his brigade accompanied the expeditionary force to france and helped to cover the retreat from mons, bringing off at cerizy one of the rare cavalry charges of the war. he went out to egypt to command the desert column in 1916, and won early distinction by the decisive surprise attack at rafah, which finally freed sinai from the turks. after the second battle of gaza in april 1917, he succeeded general dobell in command of the whole eastern force. when general allenby came out to take over the supreme command he based his plan on chetwode’s plans, and the latter, commanding the xx. army corps, after chevalier—chicago the reorganisation of the forces, played a distinguished part in the advance to jerusalem and in the crowning victory in sept. 1918. shortly after the war, chetwode was appointed military secretary at the war office, then in sept. 1920, succeeded general harington as deputy chief of the imperial staff, and two years later became adjutant-general to the forces. this post he gave up in april 1923, taking the aldershot command. chevalier, albert (1861~10923), british comedian (sce 6.113), produced at the lyceum theatre, london, in 1920, a play my old dutch, based on the famous song of that title. he last appeared in nov. 1922 at the same theatre in a revival of this play. he died in london july 10 1923. cheyne, thomas kelly (1841-1915), british divine and biblical critic (see 6.116), died at oxford feb. 16 1915. his later works include the two religions of israel (1910); afines of isaiah re-explored (1912); the veil of hebrew history (1913), and fresk voyages on infrequented waters (1914). chicago (sec 6.118).— with a population in 1920 of 2,701,705, an increase of 23:6% over 1910, chicago easily maintained its position as the second city of the united states. the census bureau estimated the population on july 1 1925 at 2,995,230. on the basis of the daily increase it was announced that the city had passed the 3,000,000 mark aug. 10 1925. while the city’s growth from 1910 to 1920 was greater proportionally than that of new york it was considerably lcss absolutely. the percentage of increase was less than that of any other decade, and the estimates of present growth indicate a still smaller rate of in- crease for the present decade. in common with most american cities, the population growth of chicago has decreased relatively to the growth of the outlying communities of its metropolitan area. the total population of the city and these districts was estimated officially as 3,986,331 on jan. 1 1925. the rate of regional growth about the city seems to be increasing as the rate of strictly urban growth declines, laxgely because of the extension of motor traffic and hard surfaced highways. chicago’s percentage of population increase in the last census decade was smaller than that of detroit, 113-4%, and cleveland, 42-1%, these two cities being chicago’s closest rivals in the middle west. negro population.—in 1920 the negro population was 100,594, an increase of 148-5 % over the preceding census. the influx of negroes was due to the demand for unskilled labour, especially in the packing industry, during the period of the world war, when european immigration was slight. a shortage of housing facilities for these negro labourers was one of the underlying causes of the race riots of r919. the negro influx slackened during the industrial depression of 1920-1, to be resumed in 1923. in the following year it again declined, and with the rapid develop- ment of conveyor and construction machinery to displace manual labour the movement has probably passed its crest. by annexa- tion of suburban areas and accretion on the lake front the area of chicago increased from 191°4 sq. m. in 1910 to 204-9 in 1925. indusiries.—the value of manufactures produced in chicago increased enormously between 1921-3, but as 1921 was a year of industrial depression and 1919 a year of very high prices, the rates of change between the three censuses are not an accurate index of physical volume. the value of all products in 1919 was $3,657,424,471; in 1921 $2,185,819,374; in 1923, $3,323,341,460. but the physical volume of the output of 1923 was undoubtedly greater than that of 1919. in 1923 there were 9,334 manufactur- ing establishments within the city limits of chicago. these employed 385,685 persons, paying wages which amounted to $571,724,743. | | despite financial difficulties and reorganisation of two of the great corporations the packing industry has maintained a growth in its receipts and output, in the face of the pronounced trend toward decentralisation of the industry. in 1924 the in- dustry showed the turnover of livestock to be 18,653,539 head, valued at $528,489,268. the trend of the grain trade is shown by the following facts. between 1920-4 flour increased from $955,000 to $1,858,000, wheat from $28,997,000 to $69,012,000, corn from $85,487,000 to $99,524,000 and oats from $74,939,000 603 to $82,831,000, and in the case of corn and oats higher figures were reached in intermediate years. the growth of the city’s financial power has been marked by the growth of the indepen- dent suburban banking, fostered by the illinois laws, and asso- ciated with real estate and suburban operations building up the ting of communities about the city. some of the outlying insti- tutions can now rival the central banks. the city plan.—the most striking feature of chicago’s recent history is the plan for the reconstruction of the city and the progress of its execution. this plan had its genesis in a report, prepared under the guiding spirit of mr. daniel h. burnham. the first step was the appointment of the chicago plan commis- sion, composed of aldermen and citizens. in furtherance of the chicago plan, roosevelt road was widened between ashland avenue and michigan avenue; michigan avenue was widened between roosevelt road and the river, and between the river and chicago avenue. widening the part of the street between randolph street and chicago avenue was a difficult matter, involving the acquisition of valuable private property and the construction over the chicago river of a large two-level bascule bridge. the new thoroughfare was opened to traffic in 1920. twelve major street improvements are now either under way or finished. the strect scheme in the plan of chicago is divided into four phases, the first of which is the project to reduce con- gestion by means of the development of a quadrangle of wide streets about the business centre. other phases of the plan, all of which are designed to provide through traffic systems by the widening of streets, the creation of boulevards, drives through the growing park system, and bridges over the river and railway depressions are in process of piecemeal execution. the chicago plan is being carried out in co-operation with the park boards and forest preserve system with the view of realising the artistic and humanitarian advantages of three features of the city, the lake front, the chicago river and the belt of wooded country about the city. the south and lincoln park boards have been reclaiming land from the lake until nearly half of the city’s water front now consists of parks and artificial lagoons. over two sq. m. have been added to this area and a further extension of lincoln park northward has been authorised by the voters. the lake front park system and the smaller inland parks have a total of 71 bathing beaches and pools attended in 1924 by 3,523,393 people. the large and small parks together number 211, with an area of 5,524 ac.; there are 25 free and 4t private golf courses, and 73 playgrounds frequented by 5,000,000 annually. inland, the city is being gradually encircled by the forest preserves, which con- tained over 28,o00 ac. in 1925 and are being extended. the recreational facilities of the forest preserves were used by over 3,000,000 visitors in 1924. the development of the south park system on the lake front south of the chicago river, is proceeding hand in hand with railway terminal development and the opening of new boulevards through the park to provide better access to the south side of the city. the illinois central railway, formerly on the lake front, is now inland occupying a depressed area in the parks. electrifica- tion of this railroad within chicago will be completed in 1932. the new building for the ficld museum, located on made land on the lake front, was completed in 1920 at a cost of $6,000,000, which was provided by the will of marshall field. it is 350 ft. wide and 700 ft. long, and is built of georgia white marble in the ionic style of architecture. south of the field museum is a large. stadium—soldiers’ field, the ultimate seating capacity of which is expected to be 100,000. railways — although chicago is the greatest railway centre in the world and the hub of the american rail system, its terminal problems have not yet been solved, although a great advance toward that end has already been made. in 1911 the new pas- senger station of the chicago and north western railway, a dignified structure, was opened to service. the railways using the union station—the pennsylvania, the burlington, the chicago and alton and the chicago, milwaukee and st. paul—completed in 1925 their terminal just south of the 604 northwestern station at a cost of $75,000,000. with the con- struction of a mail terminal this settled the problem of the six railroads with terminals on the west side of the chicago river, but the 32 railways using the three stations on the south side of the business district have not worked out a comprchensive plan among themselves or with the city. the new illinois central station to be constructed at 12th street may be used by all, or other terminals may be built further south, but any plan involves the straightening of the chicago river and the opening of five new direct north and south streets. chicago took front rank in the great building revival that marked the end of war conditions. under the zoning ordinance the height of buildings is limited to 264 ft.; but towers, if set back, are permitted. municipal undertakings —one of the most important munic- ipal undertakings is the municipal tuberculosis sanatorium, erected after 1909, in which year a site of 164 ac. was acquired in the north western part of the city. its revenues, derived mainly from taxation, amount to more than $1,000,000 a year; in 1920 there were about 1,000 patients. a notable structure completed late in 191§ is the municipal pier. it projects 3,000 ft. into lake michigan just north of the mouth of the chicago river. the outer portion, 660 ft. in length, is a three-decked structure devoted to recreation purposes. the new pier has not been much used by shipping interests but the recreation part of the pier proved popular from the outset. industrially the trend of chicago is toward the electrification of manufacturing and transport. the city’s electrical equipment now includes the largest steam generating station in the world, and a series of great stations to the north and south inter- connected for the exchange of current. within the city proper the consumption of electric current in 1924 was 845 kw. hour per capita against a general american average of 518. education and the fine arts—in chicago there are two large universities of national reputation—northwestern university and the university of chicago. students to the number of 25,400 were enrolled in the seven recognised universities in chicago in 1924. there are 304 public schools with an enrolment of 485,885 pupils, employing a teaching staff of 12,125. three large public libraries contain a total of 2,000,000 vol., with an average daily circulation of 33,300 volumes. the art institute of chicago has a larger attendance than any other art school. five of the city’s music schools alone had an attendance in 1924 of 19,000 pupils. the trustees of the art institute administer the ferguson monument fund, left by the will of benjamin franklin ferguson, to be used for the erection of statuary and monuments in chicago. among others, two notable pieces by lorado taft have been purchased; one ‘‘ the fountain of the great lakes,”’ stands just to the south of the art institute; the other “ the fountain of time,” at the head of the midway, between wash- ington and jackson parks. chicago was the first american municipality to give direct official encouragement to local art. in 1914, at the suggestion of mayor harrison, the city council appropriated $2,500 for the purchase of works by resident artists and sculptors, and an appropriation has been made each year since. the city’s musical life has been stimulated by grand opera, which became a fixed institution in 1910, with the establishment of the chicago opera association. the chicago civic opera co. has lengthened its season and in 1928 inaugurated a policy of employing americans although retaining notable european singers. finance-—chicago’s finances have been readjusted to post-war values and the disappearance of excise revenues from the liquor traffic, but the city’s capacity to incur debt ts still restricted by provisions of the state constitution to a degree unknown by other great cities of the world. a summary of the city’s most important revenues and expenditures for 1923, the last report available, gives a total revenue of $137,928,745.09 and expend- iture of $130,765,478.19. this does not include expenditures for the larger parks, for the sanitary district, or for other purposes which are in the hands of separate taxing bodies. history.—carter h. harrison (dem.), who was elected in ro1t to his fifth term as mayor of chicago, was succeeded in 1915 by chicago, university of william hale thompson (rep.), who was re-elected in 1919. after the united states entered the world war, thompson was criticised for various actions that seemed to indicate a reluctant support of the war policy of the government. william e. dever (dem.) was elected in 1923. to the surprise of the ‘ liberal ” element the mayor publicly announced that the police would hereafter be required to act in sympathy and co-operation with the governmental agencies striving to enforce prohibitory laws. the long-drawn-out litigation over the right claimed by chicago to withdraw 10,000 cu. ft. of water per sec. from lake michigan for diversion into the drainage canal for the dilution of sewage resulted adversely to the city in the supreme court of the united states in 1925; but fears of a disaster to health were alleviated by a permit to withdraw 8,500 cu. ft. per sec. pending the execution of a programme for metering the con- sumption of water by domestic users to eliminate waste, and the construction of sewage disposal plants over a period of years to dispose of sewage according to modern methods. during the execution of this programme the amount of water withdrawn is being progressively reduced. a proposal to settle the trans- portation difficulties of the city by the municipal purchase of the surface lines and building elevated extensions and subways was defeated by a referendum vote in 1925. the disappearance from the newspaper field of the inter-ocean and the herald left chicago for a time with only two english morning dailies, the tribune and the herald and examiner. \n 1920 the chicago journal of commerce was established as a morning paper for business men. the joseph medill school of journalism was opened in feb. 1921 asa part of the north- western university. the chicago tribune, of which joseph medill was founder, agreed to underwrite the deficit of the school for a five-year period. abandonment by the american steel industry of the ‘pitts- burgh plus ” system, under which the price of steel to consumers was formerly the market rate plus the freight from pittsburghtto the point of consumption, no matter where the steel was made, has already resulted in great stimulation to the steel industry on the lake front south of the city. the twenty-eighth eucharistic congress of the roman catho- lic church was held in chicago, june 20-24 1926, being attended by the papal legate, cardinal bonzano, and seven other euro- pean cardinals, in addition to the american cardinals. this was the first occasion upon which a eucharistic congress was held in the united states. cle.)