■J* *Mf^ r# .^i0mi»:t' ALBERT R. MANN LIBRARY New York State Colleges OF Agriculture and Home Economics AT Cornell University Cornell University Library QD 251.M69 Cod-liver oil and chemistry. Cornell University Library The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924002976243 rlSHING BOAT OVF LOUOTEN COD -LIVER OIL AND CHEMISTRY /% BY Ff PECKEL MOLLER, Ph.D. AUTHOB OP 'VEILEDNING VED BEDOMIIELSEN AE MEDIOINTBAN ' ' NOGLE NOBSEE FOBHOLD ' 'BT HUNDBEDAABS JTIBILiEUM' 00-AUTHOB OP ' PHABMACOPCEIA NOEYEGICA 1870' ETC, LONDON PETBE MOLLEE, 43 SNOW HILL, E.G. AND AT CHEISTIANIA, NORWAY AND CAN BE HAD FROM W. H. SCHIEFFBLIN & CO., NEW YOEK AND PROM A. T. MOLLEE & CO., COPENHAGEN 1895 CONTENTS OOD-LIVBR OIL PEEFAOE. NORWAY .... Country People .... The Vikings . The Fall of Norway The Norwegian of To-day Temperance Question Land in Norway . Norwegian Shipping NORWEGIAN FISHERIES The Norwegicm Seaboard The God Fisheries Gydefiske . Loddefiske . Lofoten Fisheries . Lofoten Norwegian Fishermen FisM/ng Boats Boats' Crews . Fishing Tackle . Nets . Longliues EandUnes Bait Social Customs The Cod-fish The Swpply of Fish FAQB vii ix iz X zi xii xiii XV xvi . xvii xix xix xxi xxi xxii xxii xxii xxiv , xxiv XXV xxvi xxvi xxvi xxvi , xxvii , xxvii xxix xxxi Lofoten Fisheeibs (continued)— The Fishing xxxii Locality xxxii Fishing Operations xxxiii Deep Sea Temperature . Fishing Operations (continued) RoMSDAii Fisheries .... FiNMAEK Fisheries .... Got Fishery Lodde Fishery Summer and Autumn Fishery xxxiv xxxvii xl xl xl xl xlii COD-LIVER OIL xliii The Liver Manufacturing Methods in Norway Cod-liver Oil from other Countries Adulterations .... PETER MOLLER'S NEW PROCESS PHARMACEUTICAL ANNOTATIONS CHRONOLOGICAL SYNOPSIS NEW RESEARCHES Contributed by P.M.Heyerdahl xUii xliv 1 lii Iv Ixi Ixxi CONCLUDING REMARKS . . . . c Retrospect c Rancidity cii Preparations civ Active Principles cvi Recapitulation ex CHEMISTRY THE LAW OF ATOMIC LINKING diagrammatioaUy illustrated, pp. 1-508. 194696 PEEFACE When our firm was established by tbe late Peter Moller he laid down this principle — that those who use the commodity we prepare have a right to know all that we know concerning it. Since then a long period has elapsed, but that guiding principle of our founder has been constantly borne in mind ; and in order to carry it out we have from time to time published monographs on various matters relating to cod-liver oil. These papers, however, do not seem to have attracted the attention that we venture to think they deserved, and in regard to the subject there still seems to be some amount of misconception, even in the best and latest text-books. Hitherto our publications have been in a language that is perhaps not very accessible to English readers ; and as that may explain why the subject is not better known we have determined to issue this volume written in English, and dealing with all matters connected with cod-liver oil, and especially those likely to. be of interest to members of the medical profession. That, however, is but the reason in part. Our former papers have been published, not at indifferent times, but at the times when we happened to have something new to tell. This we now have in the results of the investigations lately undertaken by Mr. Heyerdahl. It is not too much to say that his discoveries make by far the most im- portant contribution to our knowledge of cod-liver oil. In fact, they throw the first and only true light on that mystery, the real nature of the oil ; and to make this known is our second reason for issuing the present work. In addition to the general information regarding cod-liver oil and the results of Mr. Heyerdahl's investigations we have utihsed the opportunity to present certain viii PEBFAOE other matters only indirectly connected with the subject proper. A more particular account of our reasons for iatroducing those extraneous matters will be found at the beginning of each section, and we hope that in some of them something of suificient interest to be readable may be found. The authorities for statements not derived from personal knowledge are too numerous to be specified in all cases, but here special reference must be made to the large amount of information derived from Captain Juel's many able and interesting papers on Norwegian fisheries, published in Norsk Fiskeritidende ; and to Mr. F. Wallem's valuable official reports on fishery exhibitions in various countries ; and, lastly, to the yearly statistical reports of the superintendents of the Lofoten fisheries. 43 Snow Hill, London, E.G. NORWAY THE LAND OF THE MIDNIGHT SUN AND OOD-LIVBE OIL In these days we are not all labelled exactly as we would wish. Poor Diogenes is ' a man who lived in a tub and did not wear any clothes to speak of ; and who knows or cares about his philosophic learning and doctrines? Eome is ' that big town where I bought these beautiful stockings,' and nothing more, to the young lady who has just ' done Europe.' Scotland is the land of ' cakes and kilts,' although it is said that there are canny Scots who could not tell a cake from a bannock, and who have never seen a kilt except as a somewhat embarrassing adornment to the English tourist. Were it possible to imagine anything so dreadful as a Scotchman parodying Burns he might well exclaim : — ' wad some pow'r the giftie gie us,' Tae lat folk ken hoo they should see us. As we do not seem to have acquired that * giftie ' yet, we must resign ourselves to our fate, and try to accept our fame from the wrong end : with thanks. The fate of Norway is the midnight sun and cod-liver oil, but there are some other good things in the country, and the writer — him- self 'made in Norway' — ^may be pardoned if he tries his little best to direct attention to them. A wider knowledge of these matters would certainly increase the sympathy and friendliness of the English people for their Norwegian cousins, and it is just possible that a more inti- mate acquaintance with the land where cod-liver oil is made, and with the people who make it, might increase even the present appreciation of that excellent article. The Gountry — General Physical Features.— Norway is practically a vast mass of mountains stretching from the North Cape southwards for over a thousand miles to the Skager Rack — a great bulwark thrown up by Nature to shelter the low-lying countries around the Baltic from the Arctic and Atlantic storms. We have our doubts as to the inhabitants of these regions feeling properly grateful to their protectors, and even the Norwegian himself is at times tempted to think he could get on without quite so many hills. None the less he is proud of them, and justly, for they have a character and a charm that are all their own. Most of the great moun- tain ranges of the world can be taken only in graduated doses — the ascent of successive sum- mits revealing higher and yet higher peaks beyond. In this way much of the effect is lost, but not so in Norway. There the mountains rise sheer up from sea to summit, and the combina- tion of grey sea and sky, steep green slopes, dark frowning rocks, and snow-clad peaks forms a picture which is at once different from anything elsewhere, and is in itself impressive and sublime. NORWAY Whilst the mountains have decidedly the best of it in Norway, they have not succeeded in annexing quite everything, for here and there grea.t rents break into the general mountain mass. These rents would be the valleys in other countries, but in Norway the ocean claims them as her own, forming the wonderful fjords — great waterways, nobler than the far-famed Rhine or Hudson, running from the sea to the centre of land, sending oflF branches now to this side, now to that, frequently closed in upon by the mountains jealous to say, ' Thus far shalt thou come, and no farther,' but again opening out and winding on under threatening cliffs, round snow-clad hUls, past the thunder of waterfalls, past the grey gleam of glaciers, a bewildering, never- ending, ever-changing revelation of Nature in one of her wildest, grandest moods. Norway is thus very much a ' land of the mountain and the flood,' and while these in their own way are no doubt excellent institu- tions, a nation cannot live by them alone. Unfortunately the other things seem to have been forgotten when Norway was being made. The area of land that can be culti- vated is less than one half per cent, of the whole, or, to put the matter in another way, although Norway is larger than England, Scotland, and Ireland combined, its total arable land is barely equal to one of the smaller English counties. Nature, however, is always kind, and if she has been somewhat niggardly to Norway in the matter of land fit for the plough, she has given a compensation — the sea. Of this Norway has plenty. In fact the sea may be said to be 'laid on,' after the manner of gas or water, to almost every house in Norway. The vast coast line, which, including the fjords, may be put down at about 4,000 miles, brings the sea to every town and practically to every hamlet in the land, and the sea brings with it two blessings that make Norway what she is. One of those is the ' harvest of the deep ' — a harvest of immense importance to Norway, and about which an account will be given in a later part of this book. The other blessing is of even greater moment; indeed, without it, the Norwegian would soon be as extinct as the dodo. It is in short the warmth that makes Norway a land where man may dwell. A more detailed account of this also will be given later, and all that need be said here is that nothing about Norway is more re- markable than that it should be a habitable country. Perhaps this may seem more striking if we remember that the country lies in the same latitudes and right opposite the perpetually ice- bound shores of Greenland, and that nearly half the coast of Norway is actually within the Arctic Circle. The People. — If Norway as a country is thus unique, its inhabitants are not less so. There are in the orthodox fashion two distinct races, the aborigines and the invaders, and these are respectively the smallest and the tallest of European peoples. The Laplanders, the origi- nal avTO'xjdovss, can only succeed in reaching an average height of five feet and half an inch. According to the anthropologist they are brachy- cephalics — a most mortifying circumstance. Fortunately the Lapps are not likely to hear much about it; but if they should, they may calm their injured feelings by the comfortable assurance that things might have been worse. Indeed, fate might have placed them in Pro- fessor Sergi's hypsistenoclitobrachymetopusste- nocratophicusneocaledonensic group, which we shall not further indicate, having no desire to bring this misfortune home to anybody. But to return to the Lapps, or Finns ' as they are called in Norway. They are very few in number, and are now to be found chiefly in the extreme north of the country, where, for the most part, they live a nomadic life, subsisting on their herds of reindeer. They have all been converted to Christianity now, but they still retain a firm belief in devilry, exorcism, second- sight, and other inherited superstitions. The Norwegians proper, the invaders, are a branch of the great Teutonic group of peoples. ' Of course the Lapps have no connection with Finland or the ^inlanders, who in Norway are known as Quanes. NORWAY XI There is nothing brachyoephalic about them ; they are a long-headed race, and long in another way, as they reach an average height of 5 feet 8^ inches. This is ' the record ' for European nations ; the next places being taken by the Scotch and the Swedes, whilst the English come in as a fairly respectable fourth with 5 feet 7 inches. It cannot, there- fore, be said that the Norwegians are deficient in quantity — in quality, they are of course sans reproche in the opinion of the writer. Natural modesty keeps him from parading abroad the good qualities of his countrymen, but if anyone is in doubt about them, let him go to Norway and see the people as well as the scenery, and he will by no means return dis- appointed. In the formation of their national character, no doubt the Norwegians owe a great deal to their country. It is not exactly ' a land flowing with mUk and honey,' but it is a land eminently fitted to cradle a brave, hardy, adventurous race, and this the Norwegians ad- mittedly are. They are not a numerous people — at present numbering only about 2,000,000 — but in shaping the destinies of Europe they have done more than many, if not, indeed, than any, .of the far more numerous races. The Vildngs. — In olden times the Norwegians must have found the problem of existence no easy matter, and when they were forced to the conclusion that ' something had to be done,' it was pretty much a case of Hobson's choice. Hemmed in by the mountains on every hand but one, that one was their only course ; they must ' go down to the sea in ships,' and they did, as not a few people came to know — to their cost. The Vikings were not, however, the bar- barian, bloodthirsty rufiians depicted by Anglo- Saxon and French chroniclers. For their time, indeed, they were a civilised and cultured race, with a wonderfully perfect legislation that will bear the brunt of criticism even in this present day. Warfare was the spirit of their age, and the Viking expeditions were the only school where young men of high birth might make a reputation by Their gods were place of fighting time for the feast Their hell was a darkness, the fate were unfortunate famous and heroic deeds, gods of war, their heaven a from the sunrise until the in the great hall of Valhalla, place of cold and damp and of cowards and of those who enough to die of old age or The , Vikings are, therefore, hardly to be judged by the standards of the nineteenth century. Judged by the standards of their own age, they did that which was right in the eyes of men, and they did it well. Their adven- turous voyages extended to almost every land of the known world. Their long, dark, low- hulled craft swept every coast, and whenever they could find a landing place it was veni, vidi, vici. In Northern Europe, on the shores of Ilmen lake, the Viking Rurik laid the foundations of a state (a.d. 861), which has grown into the great Russian Empire. In Southern Europe they conquered Naples and Sicily (a.d. 1072). They were the foremost in the great conflict of the Cross against the Orescent, and for generations a company of Viking volunteers formed the body-guard of the Byzantine em- perors. Towards the west they found their way as far as North America, a fact that until lately does not seem to have been known outside of Norway. Tet Leif Erik- son looked upon the shores of the New World (a.d. 1000), nearly five hundred years before the famous Gfenoese discoverer was born, and not long afterwards a Viking, Thorfin, established a Norwegian settlement in New England, and there his wife Gudrid bore him a son, Snorre, the first 'native born American' of European blood. The inhabitants of the British Isles knew the Vikings weU — and loved them little. Their, frequent visits to Scotland have left many traces, both on the population and the language, and in Ireland they founded the towns of Dublin, Waterford, and Limerick. To the English people, however, the one episode of the Vikings is the story of Rollo and those Xll NORWAY who sailed with him on that tnemorable expe- dition which resulted in the conquest of the greater part of Prance, the formation of Norman chivalry, the destruction of the Saxon power at Hastings, and therefrom the develop- ment of the England of to-day. This EoUo or Rolf, surnamed the Ganger (the walker), because no horse could be found high enough to lift him off his feet, was con- demned to exile by the king, Harold Pairhair. He went, but not alone, for he was the hero of the 'Young Norwegian,' and what were kingly smiles to be weighed against the wild adventures of a foray when ' the Ganger ' led the way ! And so they sailed, as their fathers had done before them, a reckless band caring not what lay in front, ready for anything the gods might bring ; but little dreaming that in their hands they held the fate of nations, that their foray was to change the history of the world. It may interest some English people to know that the home of RoUo's childhood still exists. He was the son of Ragnvald Morejarl (the Earl of More), and visitors to Sondmore (South More) who care to make a pil- grimage to the island Vigra will there find Roald (Rolf's hall), and near it the ancient ship- yard, whence doubtless many a Viking craft was launched. In the neighbourhood, also, are several other ancient remains connected by tradition with Rollo and his Viking ancestors. The Fall of Norway. — The Viking age was no doubt the golden age of- Norway, but it meant a serious drain upon the Norwegians. The best and bravest were ever sailing away over the Northern Ocean — and they seldom returned. The sea claimed them, or the battle, or they found their homes and their work in other lands as leaders of men, as moulders of the nations that were rising from the chaos of the middle ages. The signs of this drain of strength were not, it is true, very markedly shown, and the Norwegians who remained at home might have held their own against all comers had it not been for the intervention of a more terrible invader — the pestilence of 1349. In these present days we have our epidemics and other outbreaks of disease, and though they are bad enough, they do not enable us to form even a vague idea of the calamity that now over- took the Norwegian people. The shadow of the dark wings rested on every town and village and homestead in the land. None were spared — gentle and simple, rich and poor, youth, man- hood, and old age, shared alike and equally the common fate. Everywhere was the sound of mourning, save where, in silence, only the dead were left to bury the dead. In many parishes and valleys not a single soul survived, and, when at length the hand of the destroyer was stayed, barely a third of the population remained alive. This appalling disaster was a fatal blow to Norway's power, and also to her independence. Never thickly peopled, the country was now little better than a desert, and its few remain- ing inhabitants were paralysed by the calamity and scattered over a wide region unfavourable for defensive combination but everywhere open to attack. Her enterprising neighbours were only too ready to take advantage of Norway's helpless condition, and she was soon turned into a kind of ' sphere of interest ' for the advantage chiefly of the Hanseatic towns. .But even yet the cup of Norway's miseries was not full. Her crown passed by inheritance to the Danish kings, but they, not content with such a peaceful union, eventually turned it into possession by right of conquest, and now indeed the glory had departed. Norway was a mere province of Denmark, and in this state of de- gradation she remained until the beginning of the present century. At the end of the Napoleonic wars Denmark found herself on the losing side, and the triumphant allied powers decreed for her punishment that she should hand over Norway to the Swedish king. This was no doubt a most convenient arrangement — from the Swedish point of view. The Norwegians, how- ever, felt that they also had some little interest in the matter, and, calmly ignoring the allied powers, they determined to settle their own NORWAY zui affairs to suit themselves. They had had quite enough of playing the part of a province, and they declared Norway once again a free and independent land. They knew that they were now too strong to be coerced, by either Sweden or Denmark, and they knew the decree was not likely to be forced upon them by the allied powers, who were far too much in love with the peace they had just obtained to think of risking it for anything of the kind. The Norwegians were perfectly successful in carrying their point, and they then entered into a defensive union with Sweden, nothing being in common except the crown and the ambassadorial and consular representation. This union has not, however, been alto- gether a success. The Norwegians considered it a partnership on equal terms, and naturally expected a partner's share in the control of foreign matters. The Swedes, on the other hand, did not quite see this view, and they showed so little haste in making the necessary re-arrangements of their Foreign Office that — it is not done unto this day. Thus the share obtained by Norway was merely nominal, and thus also the little ' rift in the lute ' appeared, and, after the manner of its kind, it grew until in 1885 the erstwhile happy union seemed perilously near divorce proceedings. The crowning cause of offence at this time was a change in the organisation of the Foreign Office by which even the nominal influence that Norway had so far enjoyed was reformed out of existence. The Swedes did not seem to think it necessary that their consort should be a con- senting party to this arrangement, but for once their high-handed proceedings had gone too far. In Norway universal indignation prevailed. The moderate counsel of the conservative, party was to try the influence of sweet reason- ableness once again, but the radical party, who had a small majority in the Storthing, proposed that Norway should do as she was done by, and manage her foreign affairs for herself. The King then used his suspensive veto to the best of his ability. He repeatedly changed his ministry from radical to conservative, and vice versd, and is at the present moment (1894) governing the country with a conservative ministry in the face of a radical majority in the SUyrthing. The Swedes rather tardily recognised the mistake they had made in 1885, but, being the larger of the two nations, they will not listen to the claim of equality; which is, perhaps, natural enough from their point of view; and thus the quarrel still drags its weary way. At present the matter seems to be again approaching a crisis — indeed, it has become so acute that it may be heard of even outside Norway, and frequent references to it appear in English newspapers, generally under the astonishing title, ' Home Eule in Norway ' ! The Norwegian of To-day. — It is a far cry from the Berserks, who followed Rolf or Regnar Lodbrok, to the present-day Norwegian, but he nevertheless is the direct descendant of the Vikings. In his veins flows that very blood which is the boast of aristocracy, and which, the genealogists tell us, runs from Harold Fairhair (936) through every royal line of Europe, those of Turkey and Montenegro alone excepted. In England nowadays very few of the nobility and gentry can go back to the sacred Roll of Battle Abbey and the unkind person might call their claims to Viking blood just a little bit shady. Certainly if they do have it, it is in very ' dilute solution,' but none the less most highly prized. The old Norman families, how- ever, such as the ducal houses of Norfolk, Leinster, and Northumberland, the noblest of the noble, the proudest of the proud, are blood relations to the Norwegians, to simple folk — mayhap deck hands on trading skiffs, or poor cod-fishers off Lofoten. With all these high and noble connections we would naturally expect the Norwegian to be a most aristocratic personage, and so he is, to his very finger tips, in many ways. He is no despiser of pedigrees, and men in every station of life are to be found, including nearly all the udal farmers, who can trace their ancestry farther back than most of the nobility of other XIV NORWAY lands, many of them indeed being able to prove direct descent from the old Norse kings. But despite all this the Norwegian is very much the democrat. The Saga relates of Eollo the Ganger and his men that when they landed in France one of them was asked, ' Who is your master ? ' and he replied, ' We have no master, we be all equals.' Even the long series of misfortunes through which the Norwegians have since passed has not stamped out that strong sense of self-esteem. They hold that ' all men are equal,' and in Norway, no matter what his fortune or his forefathers, ' a man's a man for a' that.' The result of this curious mixture of the aristocrat and the democrat is sometimes almost comic. The Norwegian will acknowledge no man as his superior — openly : but his soul longs for distinction honoris causa. Were the old sea- kings to come to life again he would throw pru- dence and everything else to the winds and sail away with them to foray and fight, and die for that vanity of vanities — empty glory. As it is, however, he has to content himself with things much more prosaic. Nowadays he descends upon the coast of France or England in the unromantic form of a Cook's tourist, and at home there is but one ' distinction ' to which he can aspire, ' the most sacred order of St. Olaf.' That such an order should be tolerated by a people professedly democratic, nay even republican, is in itself, of course, an anomaly, but it is still more surprising to see the radical party, when out of office, fervently urging its abolition in the interests of the public weal, and, as soon as they succeed in seizing the reins of government, hastening to deck themselves with its despised, yet comforting insignia. But perhaps the climax is reached when we see two of Norway's poets, writers of world-wide reputation, taking from each other a solemn vow never to accept a royal favour of this disparaged kind, and then, in the daily press, disputing as to who had broken the pledge — first. Despite these little vanities, however, the Norwegians on the whole are not a bad lot. They have the right stuff in them, and all the natural surroundings to bring it out— the two essentials for the making of a nation great m the true sense of the word. That they have the right stuff in them none who have studied in history the doings of the Norwegians will deny, That their surroundings have called forth their capabilities is no less obvious. Ever since the great pestilence they have had a struggle with man — a long and an uphill fight with all the odds against them, but in the end they justified themselves by success. With nature they have had and still have a daily battle for bare ex- istence, and here also the struggle that brings immediate success brings something more — strength for future and higher and better things. This is not mere idle speculation, and now that Norway is herself again, a free nation with all the stimulus that comes of freedom, she is beginning to show the world that she can do something in the 'higher paths of life.' Of course she must be judged by her fruits, but those who cannot judge without the thing odious — comparison — should bear in mind that the Norwegians number less than two millions, less than half the population of Lancashire, little more than a third the population of Lon- don. They cannot therefore be compared with a first-class nation. The doctrine of averages is strongly against the occurrence of master minds iji small communities, and it is only with such nations as her near neighbours, Sweden and Den- mark, that Norway can be fairly entered. If this be done she will not fare badly, with such repre- sentatives as the composers Grieg and Johan Svendsen, the musicians Oluf Svendsen and Ole Bull, the three brothers Binding, painter, sculptor, and composer, the politician-poet Bjom- son, and the problem provider Henrik Ibsen. After all, however, such matters as literature and art are of far less importance in the life of a nation than 'the greatest good of the greatest number.' This inevitably leads us into Norwegian sociology — a subject too vast to be treated here, although a few of its aspects which may have some special interest to English readers will be mentioned. NORWAY XV The Temperance Question in Norwa/y. — It may be said safely that the Norwegians are the temperate people of Europe ; the people to de- light the heart of the teetotal orator, unless, indeed, he be in search of employment. They were not always, however, such a bright and shining example ; in fact, not long ago they were very much the reverse. Their alcoholic heredity was of fairly respectable date, for the Vikings understood the value of ' the cup that cheers.' Their descendants, also, understood it, and so well that in 1838 the temperance question be- came perforce the question of the day. An attempt was made to limit the production of alcohol by imposing a duty of Is. id. per gallon, and this was gradually increased to the present rate of 7s. per gallon, of absolute alcohol. Also the use of stills of less than fifty gallons capacity was prohibited. Some idea of the need for this prohibition, and of the drinking powers of the Norweigan, may be gained fi-om the fact that in 1838 there were no less than 9,727 stills in use, or, in other words, every 120 Norwegians were the happy owners of a still producing spirits for their special benefit. These, however, were only the opening skirmishes of the battle against King Alcohol, and they were followed up until that individual fell from his high estate to one most humble and obscure. At present the Gothenburg system is established in every town in Norway. This means that practically the whole of the retail business of each town is concentrated into the hands of a single company, which is allowed to retain a fixed low percentage of the profits, but is obliged to distribute everything over and above amongst charitable institutions. In Ohristiania, which may be taken as an ex- ample, there is a population of 160,000, and only twenty-seven places are authorised by the company to retail liquor. These are rendered as unattractive as possible, and, as if ashamed of their calling, they hide themselves away behind their more respectable neighbours. A small enamelled plate upon the door is the only indi- cation that refreshments may be had within. The glowing lights and mirrors and show- cards of the English gin-palace are chiefly con- spicuous by absence, and, instead, the dismal light shows walls decked with scriptural texts, setting forth a solemn warning against the ' evil spirit.' There is no ' saloon bar,' no snug corner, not even a seat. No alluring siren stands behind the counter, but a ' ministering angel,' of the mature variety, glances over her spectacles with a look of kindly welcome duly tempered by reproof, and whilst reluctantly purveying the drinks, she never fails to recom- mend that crowning enormity of modern civil- isation — sandwiches. She is allowed a small percentage on the sale of these, no doubt with deep intent upon the preservation of the species whose habitat is her domain. The country districts, unlike the towns, take their temperance in the form of local option, and find it satisfactory. It is difierent, however, with the unwary stranger who does not find local option very refreshing, and has even been known to say uncharitable things strongly when he discovers that his favourite tipple can be had — fifty or a hundred miles away. It is no joke to have to send, perhaps, as far as from London to Birmingham- for the ' something ' to mix with your soda, and to those who cannot visit Norway without this ' adjuvant,' our advice would be — take the ' active prin- ciple ' with you. In other respects temperance legislation seems to have scored a success in Norway. The 9,727 stills have been reduced to twenty-four. The yearly consumption of spirits, calculated as absolute alcohol, has been reduced to three pints per head of population. Drunkenness is practically unknown ; and to the younger generation in the country districts, the sight of one who has indulged, ' not wisely, but too well,' would be an absolutely new experience. This, however, is not all, for we are told that the sins of the toper are visited upon his children in the form of a high infantile mor- tality, epilepsy, idiotcy, and insanity, and the XVI NORWAY statistical records of Norway > show ttat these undesirable legacies have been a diminishing quantity ever since temperance came into pos- session. Land in Norway. — The land question in Norway by no means holds the field as it does in certain other countries we might mention. Nevertheless it is a very interesting question, not only to those immediately concerned, but to every student of sociology. The Norwegian is essentially conservative in his nature, doing as did his forefathers ; and as a consequence his system of land tenure is a survival from the earliest Teutonic times. In its main features indeed the system does not differ materially from that seen and described by the Eoman historian Tacitus, nearly 2,000 years ago. The farms in Norway are held on a freehold right regulated by two laws of very ancient origin — ^the Aascedesretten (homestead law) and the OdeUretten (udal law). The former regulates > The mortality of infants under one year of age has been reduced to 10'86 per cent., as against 15-48 per cent, in England, 17*35 per cent, in Belgium, 21-96 per cent, in Prussia, 25-82 per cent, in Austria, and 32-36 per cent, in Bavaria. This low infantile mortality is the main factor of the rapid increase of the Norwegian population, which shows a higher ratio at present than any other European race, although the birth-rate is rather under the average. The effect of the temperance movement upon the pro- portion of epileptic and idiotic children was specially investigated by the late Dr. Dahl, director-in-chief of the Government Medical Department. He visited the greater part of the valleys in Norway, first in 1855 and again in 1865, for the express purpose of personally investigating the matter ; and he found that this unfortunate class of children had decreased by 16 per cent, during the ten years, although during the same period the population had increased by 14 per cent. In regard to insanity, in 1860 13 per cent, of the inmates of lunatic asylums were habitual drunkards ; in 1870 the proportion was 7 per cent. ; in 1880 8 per cent. ; and in 1890 only 2^ per cent. The number of suicides has decreased from 109 per million annually in 1846-50, to 67 annually in 1881-85, whilst in other countries the number has been increasing : in England reaching 85, in Sweden 95, and in Denmark 275. Crimes directly con- nected with drink have also decreased in a remarkable degree, and murder is now so rare as to be practically un- known. the inheritance of the freehold which passes from the father to his eldest son, or to the eldest ■daughter, should there be no sons. If there are several children the value of the estate is divided into equal shares, and the eldest son has to pay such shares to each of his brothers and sisters before he himself can enter into possession. The arrangement seems rather hard on the eldest son, and would sometimes really be so were it not that his burden can be lightened by the father, who, with certain limitations, has the power of fixing the value of the estate at what he thinks proper, and the children must abide by his decision. The other law, the Odelsretten, secures the freehold to the family. The holder of the farm can offer it for sale, but the members of the family have certain privileges over outsiders in purchasing it. Further, should it be sold to an outsider any member of the family can redeem it within five years by paying the original price together with compensation for any improve- ments that may have been carried out. This udal right has often been vigorously assailed. It is said to be injurious to the interests of agriculture, because the purchaser of a farm is not likely to undertake extensive improvements when he knows that he may be compelled to sell it at a moment's notice. On the other hand, and especially by those in possession, it is said to be a most excellent law, as it protects the genuine farmer from the rich townspeople, with their propensities for buying land and forming large estates. Whatever may be the theoretical right or wrong of the system, there is no denying that in practice it works tolerably well. Norway is hardly a land of smiling skies and pregnant soil, and its area is scarcely 800 square miles — from the agricultural point of view. Yet, on this mere patch of land, with some rough hill pasture thrown in, no less than one million people contrive to exist, and to hold their heads up fairly well. The udal system has also preserved for us a beautiful picture of life as it was in the days of NORWAY xvu our remote forefathers. Each Norwegian farm is the home of a little community, complete in itself, and strongly bound together by ties of common interest. The head of this community is the freeholder, the Gaardmand, and the house where he and his family dwell is the homestead, which is surrounded by a number of other families each with a little piece of land and a house of its own. The head of each of these families is known as a HusTnartd, and in ret am for his Hvsmandsplctds he assists in the general working of the farm, as a rule giving a certain fixed number of days to this yearly. The Gawrdmcmd is generally the possessor of * a lang pedigree ' extending back in some cases for nearly a thousand years, and in his own way he is as proud of this as if it were a coronet decked with the significant strawberry leaves. He would- look upon a marriage between a member of his family and a member of a Husmcmd's family as a terrible mesalliance, just as the most aristocratic families in England do in circumstances similar, yet somewhat diSerent. But although the Gaard/mamd stands very much on his dignity in some ways, in others he has no dignity at all. He makes no difference in his daily life from that of those around him. He and his labourers meet and speak, not as master and servant, but as men and equals. They dress alike and they labour alike, and when the day's work is over they sit down at a common table and fare alike, the Gaardmand presiding at the head of the board in the true patriarchal style. Norwegiam, Shipping. — ^The Norwegians are eminently a seafaring race, and they are so simply on account of what the scientist would call their ' environment.' Every tendency, hereditary and acquired, impels the young Norwegian to go to sea. He comes of a stock that has done so from the remotest ages, and certainly the heredity ought to bewell grained in. He himself has the sea and its sights ever before his eyes from the first day that he opens them, and the stories that tickle his youthful ears are tales of the sea, of the heroes of the Viking age, of the daring deeds and hairbreadth escapes of the present day, and these, mayhap, fresh from the lips of those who have seen or done them. When to all this we add that there is little to tempt the young Norwegian to stay at home, it will not seem surprising that he takes to the sea very much as a duckling to its pond. The merest child in Norway knows how to handle a boat, and perhaps nothing more astonishes a stranger on his first visit to the country than when his ship happens to meet one of the pilot- boats cruising far out from the coast, and he sees the pilot step on board, calmly leaving behind him a boy, not yet in his teens, to find his way home as best he may, ' wind and weather notwithstanding.' With this sort of training the Norwegians ought to become good sailors ; that they do so, can be testified by the English yachtsmen who have matched them- selves against the smart seamanship of the Norwegians sailing under the pennant of the New York Y.C. The truth of the Sagas, relating how the Norsemen crossed the Atlantic in their open boats, has on more occasions than one been challenged, but in 1893 it was shown that the feat was only child's play to Norwegian sailors. A crew of them made their way from Norway to Chicago in an exact model of the ancient Viking ship that was dug up at Gokstad some years ago. The model was 70 feet in length, undecked, and fitted with a single mast and square sail. Her sides were pierced for oars, some 16 feet and others 19 feet long, and she was manned by a crew of twelve sailors, one of whom humorously remarked to us just before starting, ' The only thing about which we may quarrel is as to who shall secure the 16-foct oars.' The boat in which Leif Erikson crossed the Atlantic was pi'obably much larger than the Gokstad boat, for we know that some of the Viking ships carried between two and three XVUl .NORWAY hundred men, and one of the Sagas tells us that the 'Long Serpent,' built by the celebrated shipbuilder Thorberg, was 140 feet in length. The feat of last year, therefore, proved that the tale of the Sagas was far from being impos- sible ; and another thing also was proved — that the daring spirit of the old Vikings is not altogether dead in the Norwegians of to-day. If further proof be wanted it may be seen in Captain Jorgensei^ and his mate Nilsen's astonishing voyage, all the way from England to Australia, in the ' Storm King,' a boat 30 ft. long; in Adolph Fritsch's recent adventurous journey single-handed across the Atlantic in the ' Niaa,' 40 ft. long ; or in Dr. Nansen's expedi- tion, now trying to reach the North Pole ; or the WeUman Polar Expedition, half of whose mem- bers hail from Norway. Polar expeditions and the like are, however, only for the few, and the great bulk of Nor- wegian seamen content themselves with the much more prosaic mercantile service. In regard to this, Norway occupies a most remark- able position. She is only a small country ; her population is less than two millions; and yet she owns a fleet that occupies the third place ' amongst the navies of the world, being surpassed only by those of England and the United States. But relative to her size, Norway is easily first of all seafaring nations ; for every thousand Nor- wegians own 792 tons of shipping, while the English, who come next, have only 322 tons for each thousand individuals. The mercantile navy of Norway is not the property of a few wealthy capitalists or com- panies, as is the case in some countries, but it is the people's own, and in it a great part of their savings is invested. There are few Norwegian families without a pecuniary interest in some ship or ships, or without some relatives on board them ; and in this way the shipping has become in Norway, more than anywhere else, a national institution in which everyone is in one way or other directly interested. ' England, 11,597,106 tons ; United States, 1,823,882 tons; Norway, 1,589,355 ions{Naut.Mag., September 1890). XIX THE NORWEGIAN FISHERIES In most countries the fisheries and the fishermen occupy a very secondary position in the indus- trial and social scale, but in Norway it has always been quite the reverse. The mythologies of Egypt, Greece, and Rome had special gods in plenty, but none to spare for those who reap the harvest of the sea. With the old Norse gods it was a difierent story — j35gir and his con- sort Ran were the special guardians of the fisher-folk, and seven daughters, blue-eyed and golden-haired, aided their gracious task. Even Thor, the mighty god of thunder and of storm, did not disdain the gentle art, and we read that once, with Hymer, he went fishing. Surely never before nor since did such an angler cast a line, and those who know and love the dun-fly and the spider-black might well adopt him as the angler's god — old Izaak notwithstanding. In our own fimr-de-siide age Thor and his fellow deities are a little at a discount, but none the less their story has a meaning to the philosophic mind. The gods alike of Egypt, Greece, and Norway were but the reflection of the lives and aspirations of the people, and through them we may read the tale of how the people lived and thought. This special instance throws a light upon the fisheries of Norway in pre-Christian times, and shows how largely they then bulked in the everyday life and estimation of the Norwegian people. In the middle ages our knowledge of the Norwegian fisheries becomes something more than a mere deduction from mythology. His- torical records deal with the matter, giving us a definite idea of the details and importance of the industry, and showing how fitting a school it was for an adventurous sea-faring race, and how the distinguished men and families of these times had all of them their origin in just those regions where the richest fisheries take place. The Norwegian Seaboard. We may gather from these records that the Norwegian fisheries were of very considerable value in days gone by, and they are certainly no less so in the present day. The reason for all this is to be found in the conformation of the Norwegian coast, which holds out attrac- tions of a ' highly desirable ' nature to the fish and to the fishermen who catch them. The Scandinavian peninsula may be de- scribed as a great slope, beginning at the low- lying coasts of Sweden on the Baltic Sea and the Gulf of Bothnia, gradually rising towards the west, culminating in the great mountain- chain of Norway, and then suddenly falling sheer into the waters of the Arctic and Atlantic Oceans. This sudden fall is a point of no little importance. It does not stop at sea-level, but continues downward, so that even close to the shore the soundings are frequently of immense depth, forming a deep channel which in former times must have extended along, practically, the whole length of the Norwegian coast from the North Cape to the Naze, but is now, at frequent intervals, partly filled with disin- tegrations brought down in past ages from the mountains by glaciers and rivers. This deep channel also runs into the fjords, even the longest of them, such as Hardangerfjord, 70 miles in length, Trondhjemsfjord, 90 miles, and Sognefjord, 100 miles ; and in depth nearly 700 fathoms. From the outer side of the deep channel, and running parallel to the shore, there rises a a2 XX THE NOEWEGIAN PISHEEIES secondary mountain range. The higher sum- mits of this range emerge from the sea, some- times to the very respectable height of two or three thousand feet, and in this way they form an almost continuous chain of islands — the SJyoergam-d — extending along the whole length of the Norwegian coast. The deep channel between these islands and the main- land is called the ' inner passage,' and to this the Skjcergaard. acts like a great breakwater : outside the storms may rage after the most approved North Atlantic fashion, but within the This plateau with its great wall-like western face might be described as Norway's guardian angel, holding the ocean currents in watch and ward on her behalf. It allows the warm waters of the Gulf Stream to pass, and crossing the plateau they pour into and fill the inner passage. On the other hand it keeps back the cold waters of the Arctic currents, which flow at a lower level in the ocean than the Gulf Stream, and, striking against the face of the plateau, are turned away again into the deep Atlantic bed. This formation of the Norwegian coast is Manleaid PBOFILE OP THE SEA-BEK OIT THE NOEWEGIAN COAST. sheltering isles the waters of the inner passage lie calm and undisturbed. To the outer side of the secondary mountain range the sea bed rises into a high bank or plateau. This plateau, like the string of islands, follows the general contour of the mainland. It is of somewhat variable width, and only from 50 to 200 fathoms below 'the surface. At its outer or seaward side it suddenly terminates in an enormous precipice, which at some places takes a plunge right down for about 8,000 feet to the deep bed of the Atlantic. represented by the accompanying diagram. If we regard the seaboard of Norway simply as an apparatus devised for the benefit of the climate, then it would be difficult to imagine anything better adapted for the end in view. Iced water may be a very excellent thing in its own place, but in Norway the only place for it is the bottom of the Atlantic — where it is. Warmth, again, is the one thing needful and the genial stream that brings it is not only admitted passage free, but is provided with ' suitable accommodation,' where it may rest after COD FISHERIES XXI its long journey from the Spanish Main. It is no ungrateful guest, and its kindly payment to its host is life, and all that life implies. Here, also, we see the raison d'etre for the extraordinary coast line of Norway. It has been constructed so that each and every part of the country shall share in the benefits of the ' hot-water supply ' that is, in the waters of the deep channel, and the arrangement of countless isles, and a mainland broken up by equally countless §ords provides that few districts in Norway are left out in the cold. In an earlier part of this work it was stated that nothing about Norway is more remarkable than that it should be a habitable land, but how much more remarkable is it if we consider the means by which it is brought about ! The outer wall, the plateau, the island chain, the deep passage, the i^ords — each playing its own part, each part essential to the whole, and the whole a com- bination exceedingly efficient for its purpose, and wonderfully striking as an illustration of Nature's ways. ■ The Cod Pishekies. The above conditions are not only good for man — they are also good for fish. Despite the high latitudes, the waters ofiFthe Norwegian coast are never frozen, even in the severest winters, and fish of many different species Uve and thrive in them most amazingly. The chief varieties are the herring, mackerel, ling, coal-fish, and last but by no means least, vast shoals of cod.' The cod fisheries are of two kinds — the per- manent and the periodic. The permanent fishery goes on all the year round in the waters immediately adjacent to the coast. It supplies ' The following table shows the relative importance of the various fisheries : — Cod-fish 61 per cent. Herring 25 Coal-fish and ling ... 8 Mackerel 3 Salmon and sea-trout . . 2 Lobster 1 Oyster 0-03 per cent. the daily demands in various localities, and although there are no statistics enabling us to show exactly its importance, still the aggre- gate take must be considerable. Compared, however, with the periodic fisheries, it sinks into insignificance, and from it there is no production of cod-liver oil worth mentioning. The periodic fishery is of two kinds : the Gydefiske, spawning fishery, and the Loddejislce or Pinmark ' .fishery. These entirely differ in regard to the locality where the fish are caught, the season at which they are caught, and the reason why they come there to be caught. The Gfydefiske tak.es place in the winter season all along the coast of Norway, but especially at two localities : off the entrance to Molde^ord, lat. 62° to 63°, and at Lofoten, lat. 68°. Immense shoals of cod-fish resort to these localities for spawning purposes. They appear on the fishing grounds early in January, in March they spawn, and in April they are ' gone, leaving no address.' Their exact habitat is somewhat of a mystery. Unlike the cod-fish of the permanent fishery, they do not live in the deep channel close to the land, and probably their home is on the outer plateau, especially near that part where the great wall descends to the bed of the Arctic' and Atlantic Oceans. Why they come to these particular localities to spawn is another mystery. Scientists assert that it is because there the young fry find sheltered places where they can safely grow and thrive. Of course, the scientists must be right ; but it is rather curious that some cod- fish manage to get on well enough without making the Norwegian or any other coast their nursery. Another theory puts the blame on a kindly Providence which acts somewhat after the manner of the Society for the Prevention of Cruelty to Children. It sends the cod-fish ' The definite form of a noun, in the Scandinavian languages, is, as a rule, expressed by suffixing the article, but it is not employed in compound words ; e.g fisheries of J'inmarken : Finmark-fisheries ; islands of Lofoten : Lofot-islands ; district of Bomsdalen : Bomsdal-district, &o. xxu THE NORWEGIAN FISHERIES away from home to spawn, because if the youngsters were deposited under the paternal roof-tree, and presumed to become big enough to be visible to the naked eye of their unnatural parents, the latter would probably regard them as convenient hors-d'oeuvre. The question why the fish cometo these particular grounds to spawn is, however, a point of interest only ; the point of practical importance is that they do come, and that they seem to find the place quite up to their expectations — a satisfactory circumstance no doubt to them, as it is also to those who catch them. The Loddefiske, the other variety of the periodic cod fishery, takes place ofi' the coast of Finmarken. north of lat. 70°. Here the spawn- ing fishery is not of any importance, but after it is over, that is in April, the important Lodde- fiske begins, and lasts till the end of June. The fishery is, indirectly, named from the caplin (Mallotus arcticus), in Norway called Lodde. It belongs to the SalmonidoB, and is the smallest species of that family, being only from five to seven inches in length. Its home is in the Arctic Ocean, lat. 64° to 75°, but in March or April it appears off the coast of Finmarken, coming there to spawn, and sometimes in such enormous quantities as to form a con- tinuous mass extending for many miles. In pursuit of the caplin come great numbers of gulls and whales, and ' immense shoals of cod- fish and haddock, the capture of the two last constituting the Loddefiske or Finmark fishery. Lofoten Fisheries. Lofoten.^ The Lofoten Islands^ reside within the Arctic Circle, between lat. 67° and 69°. They are part of a large group of islands arranged in the form of a triangle, the base resting on the Norwegian coast, while the apex stretches away out to sea in a south-westerly direction. ' In Englisli usually and erroneously written ' Lofoden.' ^ ' Lofot-islands ' would be the correct — but in English, no doubt, unfamiliar — form ; we have therefore retained that of ' Lofoten ' throughout. The base is called Vesteraalen, the apex Lofoten ; the exact number of islands in the group is not known to any man now living : they are of assorted sizes, from Hindo, with its 600 square miles, to Rost, which name is. represented on the map by a black dot, and on the Arctic Ocean by 365 islands, one for each day of the year, as the fishermen put it. The islands are inhabited by the Maelstrom, the Midnight Sun, and a few people ' of no importance.' They are also largely visited by callers belonging to three quite distinct grades of society. First, the tourist (var. Brit., Amer., et Germ.y, secondly, the cod-fish (var. Q. morrhua); and lastly the Norwegian fisherman, who has no particular Latin name, but is a very decent fellow notwithstanding. The tourist, unlike the other visitors, comes to Lofoten on pleasure bent, and, ostensibly to pay his respects to the Maelstrom and the Mid- night Sun, both unique characters in their way, and quite worth a visit. The Maelstrom (mill race) is near the apex of the group of islands between V^ro and Moskenseso. From the days of the Sagas its reputation has been evil, but its little misdeeds of former times are as nothing compared to the deadly sin it has com- mitted within the last few years, that is, since it went into society. The Maelstrom is one of those unspeakable individuals who have no regular visiting days, and as its habits are most erratic, not a few of its tourist friends call only to find it ' not at home.' The writer has crossed from Moskenaeso to Vsero with a sea so calm that had he not known the fact previously he would never have suspected he was right over the great whirl- pool. But, on the other hand, the Maelstrom is never to be depended onj and sometimes when not particularly wanted it is ' at home,' and very much so. Dr. G. Armauer Hansen, the well-known director of the leper hos- pital at Bergen, gives a graphic account ' of a somewhat boisterous welcome with which he was once favoured. The following extract is a free ' Natwren, 1892, p. 271. LOFOTEN FISHERIES XXIU translation : ' The waves rose, nofc as ordinary- decent waves with nice, smoothly rounded tops, but as great masses of water, curving, hollow, and foam-crested, suddenly rising, and then collapsing as if on a rock. The skipper did not seem to like the look of things, but after a little hesitation he gave the order, Go ahead. Now we were in for it, and once in there is no turning back ; the only courses are to get through, or to get swamped. Fear is unknown to me, but I must own I was not perfectly at ease when one of the great billows happened to collapse quite close to us — a little closer and we would have been gone.' The tourist who happens to find the Mael- strom in working order will be quite satisfied, and if he misses that sensation, he is certain of the Midnight Sun, for it is always ' at home ' during the season, and" ready to welcome pilgrims to its northern shrine, Lofoten. The worship of the Midnight Sun is conducted on good old ways that were familiar even in the days of Noah. These are the libation and the burnt- ofiering. The former is champagne (exact number of glasses not specified) and — it is not thrown into the sea. The burnt-offering is a hat, preferably new, and in this the devout worshipper bores a hole secundum a/rtem by means of a burning glass and the Midnight Sun. These orthodox rites being duly honoured, the pilgrim is at liberty to return to his ancestral halls, where he proudly displays ' the hole ' to his astonished and admiring friends, and — goes to buy a new hat. The writer has no wish to set up as ' the superior person,' but he would venture to sug- gest that with a certain amount of application and, say, a nail a very good hole may be made in almost any kind of hat j further, this may- be done quite conveniently at home : at Lofoten there is another and more worthy form of worship, not on board palatial steamers crowded with chaflSng, toast-drinking tourists, whose sole object is to amuse and be amused, but as far possible from 'the madding crowd,' per- fectly alone in a small boat out on the sea, or in some quiet solitude upon the shore. There to the understanding mind the solemn grandeur of the scene comes home, never to pass away. The lofty rugged hill-tops of Lofoten all around and the calm stretch of water below lie in a dark-red glow of light, and a perfect stillness, as of death, while to the north the great orb rolls in his majesty -along the nadir path. Then only may the eyes of men turn to the sun ; and standing alone in that strange light, face to face with the one Awful Presence, man ceases to think, and simply feels that with the silent earth and sea he offers adoration to the Ruler of the heavens, to the grandest work of God. The Lofoten group of islands and the Lofoten of the fishery officials are not quite the same thing. The former name is applied to the four islands forming the apex of the whole group ; while the official name is applied only to their south-easterly shores, facing Vesttjorden and the mainland. The four Lofoten islands consist of East Vaago, with an area of about 200 square miles ; West Vaago, 150 square miles; Flakstado, 32 square miles; and Moskenseso, 80 square miles. These islands lie in 68° lat. They form a pretty compact group, being separated from each other only by narrow sounds, and they are the scene of the great Lofoten fishery, concerning which some- thing may now be said. The tourist who visits Lofoten in the summer would hardly recognise the place in its winter garb. The Maelstrom is still there, but in a very different mood, and the fierce conflict of its waters is a real and ever-present danger to the fishermen. The Midnight Sun, however, is gone. Sunrise no longer combats sunset, and Lofoten no longer rises from the sea like a magic fairyland of light and shade of every hue. Still she is grand, but with a stern, cold grandeur. Her great mountains are now clothed in white immaculate, and when viewed from a distance they appear, one shining battlement, crowned here and there with giant towers. On coming nearer, however, the great mass of white begins to break up into separate XXIV THE NORWEGIAN FISHERIES mountam groups; still nearer, darker groups rise up against the bases of the white ones ; and when at length the coast is reached these darker hills open out into clusters of small islands behind which the fishing boats nestle in safety from the Arctic storms. Bach island group, together with the land behind it, forms a natural harbour, and is known as a Veer. These are pretty numerous, there being over forty of them along the Lofoten coast, and they are yet another evidence of kindly Nature's care for the Norwegian. Had the Veers been wanting, even with everything else as favour- able as at present, there would be no fishery at Lofoten — to throw up artificial breakwaters and harbours there might be a task for gods, but not for men. Such, then, is the scene that would strike the stranger approaching Lofoten in winter, in the time of the fishing, and, having personally conducted him to the theatre of operations, the writer may now be permitted to introduce the d/ramatis personce, the cod-fish and the Nor- wegian fisherman. On the principle of place aux hormnes, before the cod-fish comes that particular ' lord of creation ' who captures him. The Norwegian Fisherman. As has been already said the fisherman is not a permanent resident at Lofoten, but like the cod-fish and the tourist he comes there at a particular time aiid for a particular purpose, which being fulfilled he departs' to his own place. That place may be anywhere along the coast, even to the south of Bergen. This fact alone is a grand ' certificate of character,' for the distance from Bergen is nearly 700 miles, and in the winter the regular steamers are unable to cover it in much less than a week. Yet the fishermen do the journey as a matter of course — do it in their small open boats in the dead of winter, when the brief daylight seems to dawn only to fade away, and the darkness, with gales and snowstorms, adds terribly to the dangers of a coast that is difficult to navigate even when illumined by the almost constant summer sun. The great majority of the fishermen are tall and powerfully built, with strong, deeply cut, often handsome features. They may not seem very active on shore, but on sea they are vigor- ous and enduring to a degree, and in the face of danger no bolder or more resolute men are to be found. They are not given to much speaking. The sad, stern spirit of the Northern Sea has entered their souls, and they are silent and grave, as becomes men who day by day carry their lives in their hands. The dangers to which the fisherman is exposed are everywhere great, but in the wild seas off Lofoten they are doubly so. Some years ago over 600 men lost their lives in a single day, and on another occasion, in 1893, about 120 perished. Besides these great catastrophes there is a steady drain of life from minor casualties, some idea of which may be formed from the table below. Casualties of the Lofoten Fisheby. Tear Men engaged Wrecked Pei cent. Saved Per cent. Loss' Per cent. 1886 28,900 71 0-25 57 0-20 14 0-06 1887 28.000 174 0-62 129 0-46 46 0-16 1888 31,900 101 0-32 76 0-23 26 009 1889 30,100 60 0-20 48 0-16 12 0-04 1890 30,300 39 0-13 - 33 0-11 6 0-02 1891 30,400 180 0-69 131 0-43 49 0-16 1S92 30,100 36 0'12 28 0-09 8 0-03 1893 26,700 187 0-70 60 0-19 137 0-61 Fishing Boats. The boats used on the Norwegian coast north of 64° lat. are of quite a unique type. They are beautiful craft, exceedingly light and flexible, yet strong enough to stand the strain of the sdverest wind and weather, even when laden to the gunwale. There are several varieties,' ' The chief varieties are : — Name Length Beam Pairs of oars Uen Carrying capacity Fembbring Ottring . Ti-erbmming . Peet 36-48 28-30 18-20 Feet 8J-10 6-7 4i-6 6 4-5 2-3 6-8 3-6 2-3 Tons 7 1,200-2,000 Hsh 3i 600-1,000 „ 1 200 :; LOFOTEN FISHERIES XXV named after the number of thwarts — a method which at once indicates the size of the boat, as the distance between the thwarts is always 36 inches ; that is, the length of a barrel. The boats are fitted with a single mast and square sail — about the best rig for running before the wind — and given this condition they will show a clean pair of heels to almost anything else that sails the sea. Unfortunately it is not possible to be always running with the wind, and when it comes to beating up against the wind the square-sail rig is enough to try the patience of a Job. As a rule there is but one course — the men have to take to the oars — and when they are put to it, the amount of rowing that Norwegian fishermen can get through is some- thing astonishing. Sometimes, however, in heavy weather the struggle proves too much even for them, and nothing is left but to bear away and try to make land somewhere or anywhere. The Norwegian fishing boat has, however, yet another defect — its instability — and off Lofoten there are few things less desirable than an easily capsized craft. Squalls may be expected at any moment, and they come rushing down from the mountains with most alarming suddenness and force. The writer has seen them lift the timber houses right off their foundations, and toss small boats completely out of the water, sometimes pitching them high-and-dry upon the land. The fishermen are of course quite familiar with these nasty little tricks of the wind, and their skill in meeting them could not very well be exceeded ; but so long as they use the present type of boat, accidents will occur — and frequently. That they now do, may be gathered from the fact that during the last ten years no fewer than one- third of all the casualties at Lofoten has been due to boats capsizing. It may seem astonishing that the fishermen, knowing these things, do not make short work of the offending boats, and provide themselves with a safer form of craft. They are beginning to do so, and especially since a late storm, when it happened that a progressive individual with ' a fore and aft ' boat saved it and his crew while all around perished. Still the process is very slow, and in the winter of 1893 out of the 7,000 boats at Lofoten only about 200 were of the new type. The Norwegian fisherman is very conservative in his ways, and he does not see why the boat that was good enough for his forefathers should not be good enough for him. Further, the boat has been his home ever since boyhood ; he has grown to love it even with all its faults, and in addition he has a keen sense of the beautiful, and cannot be got to look with favour upon the somewhat unattractive although safe ' fore and aft ' substitute. Those who know the artistic merits of the present craft will here sympathise with the fisherman. It is almost worth visiting Lofoten simply to see these boats as they come racing in from the fishing grounds, now rising on the crest of a wave, now disap- pearing, boat, sail, and all ; then, as the dis- tance lessens, the foam is seen flying over the sharp bows as the stem cuts the water like a knife, and the great square sail stands taut to the wind, till rounding up, the craft sweeps into the sheltered water, a perfect picture of graceful ease. The Boats' Crews. Nowhere on earth is the ' equality of man ' more truly practised than on a Norwegian fishing boat. Birth,, wealth, and influence simply do not count, and each man ranks in accordance with one thing only — his personal worth. Very often the man who is the master at home takes the oar on board, while his servant passes to the stern and grasps the tiller, the sceptre of authority. Gene- rally the men come from the same district, sometimes even from the same household ; and from apprenticeship onwards they have day by day faced danger together, and — they hiow each other. No formal election is ever required or made, and the skipper (Hmidsma/tid) is simply the man whose strong arm, cool nerve, and ready resource are most to be relied upon in those terrible moments when the lives of all XXVI THE NOEWEGIAN FISHERIES hang on a thread. No commission of authority- rests on a base firmer than this : the crew- have themselves chosen their captain, and his ■word to them is absolute, for in the face of danger everything depends upon instant, un- questioning obedience to his orders. The post of Hovidsmcmd is thus one that can be earned only by true and well-tried ■worth. It is the aspiration of every member of the crew from boyhood onwards, but when it comes it brings a terrible responsibility. The chosen captain knows that his slightest failure or error of judgment may mean, not only the lives of the crew, but that Nemesis that is ever with the fisherman, the misery that may be worse than death to those at home — the little ones, wives, and sweethearts. The Hovidsmand's work is thus by far the hardest ; nevertheless honour is its sole reward, for not one penny extra of the joint earn- ings goes to the holder of the post. By an unwritten law the Hovidsmand retires when he reaches his fiftieth year, a younger man passes to his place, and he who yesterday held absolute command gives as absolute obe- dience to-day. The Fishing Tackle. Nets. — Three different kinds of tackle are used in fishing for cod : the net, the longline, and the handline. The net is considered a recent innovation, as it has been used only since 1685. It was not by any means a favourite at first, but has now established a firm footing in the good graces of the fishermen. The boats used for the net fishing are the Femboringer, the largest form. They have a crew of six or seven , and carry from ninety to 1 20 nets, of which each man contributes a share. The net is about 30 yards in length, and 4 to 6 yards deep, -with meshes about three inches square, just enough to permit the cod- fish to poke his nose through ; and when he has done so, he finds he can get no further, nor can he get back. A number of these nets are linked end to end, so as to form a continflous net, often over half a mile in length ; and when the boat arrives at the fishing ground the net is run out, one margin being made to sink by stones or pieces of iron, while the other is kept up by floats, hollow glass globes, attached to it at intervals. The net, thus suspended verti- cally, forms an obstruction where the cod- fish, no doubt, considers he has a 'right of way,' which it is his duty to mantain, as he does, but with results more disastrous than ' prosecution according to the law.' The Longline was introduced some time ago. The writer would rather not take the responsi- bility of saying how many centuries. The boat used for this is the Ottring, with a crew of three to five men, and the tackle is simply a strong hemp cord to which hooks are attached by means oi short cotton snoods. The hooks are about four feet apart, and a line bearing 480 of them is called a stamp, and lies baited and ready for use in a tub made by cutting a barrel in two. The line is generally run out across a current, and allowed to sink to the proper depth, where it is suspended by floats. When one stamp is exhausted, another is tied to its end, and this is continued till miles and miles ot line have been run out, so that the name ' long- line ' is by no means a misnomer. The Handline. — The fishermen who cannot afibrd a Fewhoring, or even an Ottring, content themselves with a smaller boat and handlines. These are about a hundred fathoms in length, with baited hooks attached to the end of them. The number of fishermen at Lofoten using these respective varieties of tackle is shown in the following table : — Tear Ket9 LoDgliDes HaDdHnes Total 1889 1890 1891 1892 1893 11,628 13,312 13,529 12,994 11,410 15,793 14,907 14,393 14 672 13,231 2,662 2,105 2,456 2,426 2,042 80,083 80,324 80,878 30,092 26,683 Average 12,575 14,599 2,838 29,512 The tackle forms a very heavy item in the fisherman's annual budget. This is due to the LOFOTEN FISHERIES xxvu fact that not only is it expensive to begin with, but it does not last long, for the sea seems to delight in taking liberties with fishing gear, and liberties of a most objectionable nature. Sometimes the strong currents carry nets and lines clean away; or it may happen that they are very considerately returned to land a few hun- dred miles off; but this is rare, and as a rule when the sea once gets them into its possession it keeps them. Storms cause an even greater amount of loss, for they frequently come on when the fishermen have their tackle down, and then there is no choice but to leave nets and lines to the tender mercies of the sea, which entreats them shamefully. Generally when the poor fellows do succeed in getting their gear up again after a storm, it is only to find it so hope- lessly mixed and broken as to be almost, or quite, beyond repair. The following table will give an idea of the amount lost in this way by the Lofoten fishermen: — Tear Loss of nets Loss of ' longlines Damage to nets Damage to longlines Total 1889 1890 1891 1892 1893 £ 8,400 1,700 6,600 4,400 4,600 £ 6,000 5,800 4,500 4,500 5,300 £ 16,000 15,000 14,000 11,000 11,500 4,500. 3,000 3,500 4,200 6,000 £ 34,900 25,500 28,600 24,100 27,400 Average 5,140 5,220 13,500 4,240 28,100 Sait. The anatomist tells us that the cod-fish has no brains to speak of, but he is not on that account so foolish as to try to dine ofi" iron hooks au natwel. His taste has, therefore, to be studied by the line fisherman, and the succulent dainties that meet with approval have to be procured and paid for— another im- portant item in the bill of expenses. The dish to which the cod is most condescending is his not very distant relative, the herring, and he prefers to have him fresh. But, alas ! ■ a fresh herring at Lofoten in January would be about as astonishing as the right man in the right place. In fact, whenever the shoals of cod begin to arrive all the other fish seem to take fright and their departure, and in the hauls nothing is to be seen but cod, cod everywhere. Fresh herring, however, must be had somehow, and had they are, by a most ingenious ex- pedient. It so happens that in the autumn great shoals of herring visit the Norwegia,n coast to the north of Lofoten, and as they enter the numerous ^ords, sweep-nets are carried across from shore to shore behind them. Their retreat to the sea is thus cut off, and the ends of the sweep-net are gradually drawn along the shores towards the top of the fjord. The herring are of course driven upwards by the advancing net, till at length the end of the jQord is almost reached, and there they are confined in a space so small that they have sometimes scarcely room to move. They can now be taken out of the water without the slightest trouble, and just as they are required. Some of them are imme- diately disposed of, but as herrings are of little value at that season, great numbers are kept in confinement till the beginning of the year, when they are sent south to Lofoten, and sold at high prices to b6 used as bait. The quantities of bait chiefly used at Lofoten are shown below : — Tear Fresh herrings Salted herrings Mussels Caplin Total value * Average for each line-tisher 1889 1890 1891 1892 1893 Barrels 26,000 30,000 10,000 6,000 6,000 Barrels 6,200 2,000 6,000 10,000 9,100 Barrels 2,000 3,000 1,300 1,000 600 Barrels 1,460 4,000 6,000 4,000 11,600 £ 16,400 28,300 16,100 16,100 11,700 £ s. d. 10 9 1 17 11 12 4 1 1 11 17 9 Average 16,200 6,520 1,680 6,190 17,720 1 i 2 — ' Social Customs. On his arrival at Lofoten, the fisherman makes for one of the Voers, or natural harbours, and there he establishes his headquarters for the ensuing campaign against the cod-fish. Every Veer is in the hands of one or more proprietors, who purvey to the fisherman such things as are XXVUl THE NORWEGIAN FISHERIES understood to be the necessities of life in these regions, and who also buy from him the fish that he is fortunate enough to catch. Each boat's crew is provided with a dwelling, which, however, cannot be described as 'that handsome and commodious residence.' It is, in fact, a mere hut, built of wood, roofed with birch bark, and divided by a partition into two rooms. The outer room is generally pretty well occupied by fishing tackle, and the inner by four to six men, a cooking stove, a couple of benches, and two bunks arranged, cabinwise, one above the other. Perhaps the most in- teresting thing about these rather simple domestic arrangements is the door-latch. This is a wooden lock constructed on the ' Brahma ' principle, but of very ancient origin; and to those who are int/erested in ethnological matters it may be news to hear that the primitive lock of the Syrian peasant has practically an exact counterpart in use at this present day within twenty-five degrees of the North Pole. The Lofoten fisherman is his own cook, and the results of his efforts would probably seem very dreadful to a French chef; but he himself ' takes ' them quite calmly, and thrives upon them. His bill of fare shows three principal items : dried meat, .chiefly mutton ; Lefse, a kind of soft flat cake made from oatmeal ; and Madbrod, a hard leaf-like bread, also of oatmeal. These are helped out, or down, by cheese and butter, but, in common with his brethren of the craft in other lands, the Norwegian fisherman despises fish as food for himself. When he is particularly hard up, he does, it is true, con- descend to a fish diet, and even at other times he will partake of a dish prepared from cod's tongues and Fladbrod soaked in the oil fi-om the freshly boiled liver, which he considers a dainty ' fit for gods or men.' Cofiee is his chief drink, and for reasons that we have already indicated, and over which he has no control, the Lofoten fisherman is a ' total abstainer.' The earnings of each boat are divided among the members of the crew, who rank as whole-lot men, three-quarter-lot men, and half- lot men, according to individual experience and fitness for the work. The Hovidsmand, as such, gets no larger share than any of the others. Boys during their apprenticeship generally have the proceeds of a particular net set aside for their benefit. When a boat happens to be short of hands, men hired and paid by the day are obtained from a number of fishermen — be- tween two and three thousand — who for one reason or other have no boats of their own, but who are always sure of work, Lofoten being a labour paradise where the army of the unem- ployed is an unknown evil. Serious crime is also practically unknown,' a very remarkable fact when we consider that between twenty and thirty thousand men congregate at Lofoten every season, and there pursue a calling which is bound to give rise to almost constant disputes. These do not result in the gravest consequences, simply on account of the mutual forbearance and good sense displayed by the different boats' crews. The magisterial functions are exercised by the Inspector - General of the Fishery, who is always a naval officer, and his subordinates. He sees that the fis'nery regulations are carried out, punishes ofi'enders by fines, and acts as arbitrator in matters of dispute that the men fail to settle for themselves. Should his decisions not be acquiesced in, the cases may be carried before a specially appointed judge ; if serious crimes do occur, they are sent to the regular coiirts of justice. The most frequent ofi'ence is theft, not on land, but on sea, when the tackle of different boats gets mixed, and gives a chance to those who find it difficult to distinguish between their own and their neighbour's fish. Needless to say, sinners of this kind are seldom Norwegians, but Finns — Laplanders — of whom a few are always to be found at the Lofoten fishery. ' During the last ten years the average number of grave offences was only seventeen per annum. Of these thefts averaged eight, forgeries four, and in the whole period there was not a single case of murder, and only one of manslaughter. LOFOTEN FISHERIES XXIX The Godnfish. Of the three classes of visitors to Lofoten the cod-fish are the oldest established. Their visits are mentionedin Bigil's Saga — circa 930 — and since that time, so far as records enable us to judge, they have arrived year by year with the regularity of the winter season, and in such multitudes as to defy computation. Why they have elected to go to Lofoten in preference to other places is a question that presents no difficulty to the scientific mind : the cod visit the Norwegian coast for the sole purpose of spawning, and select the regions that are specially sheltered, so that there the ova may lie in safety until they are able to shift for them- selves. This seems a very good theory, only it happens to be of the kind that requires ' facts made to fit them.' The cod-fish does not care much for its young except as tit-bits, to be swallowed whenever they come within reach, and it is rather too much to ask us to believe that a parent of this type is likely to trouble about the most suitable nurseries for its little ones. Of course we admit that natural selection may teach even the cod-fish, but there is yet another and absolutely fatal objection to the scientific theory. The seas around Lofoten are by no means quiet and sheltered — in fact they are the most exposed and stormy on the whole coast. Elsewhere the inner channel is protected by the great Skjcergaard breakwater, but the Lofoten group of islands stretch right out into the open sea, and get the full benefit of every breeze that blows, while the Vestjjord — where the spawning chiefly takes place — is simply a huge funnel into which the Atlantic storms sweep without obstruction, and where they rage after their own sweet will. The real explanation of the preference the cod-fish show for Lofoten is probably to be found in the arrangement regulating the flow of the ocean currents. Besides Lofoten there is one other point to which the cod flock in enormous numbers for the purpose of spawning : that point is Eomsdalen, about 450 miles to the south of Lofoten. Now if these two places had something in common, something not shared by the rest of the coast, it would be but reasonable to look to that for a possible solution of the problem, and it so happens that this is exactly what they do have. As has been already stated, the water close to the mainland is of great depth, but beyond this the sea-bed rises into a bank the outer edge of which suddenly slopes downwards into the deep bed of the Atlantic and Arctic Oceans. This slope is much more sudden immediately to the seaward of Lofoten and Eomsdalen than else- where, and at these two points the deep bed of the ocean runs in towards the land, forming two entering angles or bays. It would be remark- able were it a mere coincidence that these bays occur just at the places selected by the cod- fish, and not elsewhere, and the question that naturally arises is, In what way can they influence the choice of spawning grounds ? The chief end of all the lower forms of organic life is food, and as the cod-fish is pretty low down in the scale, we should expect that the question of what he can get to eat bulks largely in his estimation — much more than the welfare of youth, even as applied to his own children. His intellectual develop- ment having reached that stage where the guiding principle in life is the gastric juice, he is likely to choose his home just wh§re he can most easily fill his stomach. But even to him a plentiful supply for the digestive organs is not everything; cold-blooded as he is, he dislikes chilly waters as much as tropical currents, and, no doubt, his idea of perfect bliss is to combine the pleasure of taking his ease in a properly-cooled current from the. south, with the profit of having there the food of the deep waters from the north flowing into his mouth. This combination of comfortable circumstances is likely to be found along the edge of the great bank outside the whole coast of Norway, but the 'bays' which have been referred to are probably the means of sending THE NORWEGIAN FISHERIES a much more plentiful supply of fish food to the parts of the bank in their immediate vicinity than is to he found at any other part ; thus, these places can support greater multi- tudes of fish than could exist anywhere else. The fish food is not altogether devoid of interest. It originates in a protoplasmic basis which serves as nutritive material for immense multitudes of amceboid animals belonging to the protozoa. These form a suitable , dietary for flageUata, radiolaria, and other infusoria, which in their turn support amphipoda, deca- poda, isopoda, and other crustaceous animals which are the cod's delight. The series is somewhat like an epitome of the evolution of the lower forms of life, and, as if to complete the analogy, the simple protoplasmic substance from which the whole is built up is as mys- terious in its origin as life itself. In fact, no man knows anything as to how the proto- plasm comes into existence. It seems to bemanu- factured somewhere in the polar regions, and in quantities that almost exceed belief — we have been told by skippers who frequent the Arctic seas that they have sailed through such viscid masses for days together. The Arctic current comes from the polar regions down to Norway, but is warded off the coast by the precipitous wall of the great bank, up to the edge of which it does not reach, and along which, therefore, the cold current runs southwards, charged with the rich food for the swimming popula- tion of the ocean ; but this current is too cold for them to livp in. The Gulf Stream, how- ever, from the tropics, flowing on the top of the cold current towards Norway, establishes that happy combination of circumstances so necessary to the well-being of the cod-fish. On account of the opposite directions of the two currents, the upper strata of the Polar current must get mixed with the lower strata of the Gulf Stream, and consign to the latter some of the feeding stuff it contains, which in this way is carried back to the bank ; and thus charged and cooled, so as to be comfortable to the fish, it rises to a sufiiciently high level, flows over the edge of the bank to where the cod are awaiting its arrival ; fills the basin, the ' inner passage ' and the fjords on the other side of the edge. Where the wall of the bank runs in a tolerably straight line, this mixing of the two currents must be less marked, and the lower strata of the Gulf Stream are not impregnated with sufficient food to sustain any unusual abundance of fish life ; but the case is different where there are extensions of the deep ocean bed into the submarine plateau off the coast, forming the aforesaid bays or nooks. Of such, there is one opposite Lofoten, and another opposite Romsdalen, as will be seen from the accompanying map. The deeply- situated Arctic current enters these bays, and whilst elsewhere it is turned off into the ocean by the face of the plateau, here that is impossible. The current, in fact, is caught in a sort of trap, and as it flows on towards the apex of the nook, any escape back to the Atlantic becomes more and more difficult. Doubtless, a certain pro- portion of the inflowing Arctic water does escape by means of a deep back current, and, indeed, it might all escape in this way if the apex of the bay were sufficiently rounded. It is not rounded, however, but the very opposite, viz., an acute entering angle; and when the current reaches this, there is but one means of egress. The water pressure behind forces it on, and as there is no getting backward, it is compelled to rise up towards the surface, where, mixing with the warm surface current (the Gulf Stream), it flows over the edge of, and crosses, the bank. In this way it happens that the waters in the Lofoten and Romsdal regions are mixed with a greater portion of the Arctic current than the waters at any other point of the coast, and these regions are therefore favoured with a supply of the fish food which the Arctic current brings. Hence the cod-fish and the cod- fisheries of Lofoten and Romsdalen. On the rest of thei Norwegian coast the waters are by far not so, rich in fish food, ergo there are no cod-fish to speak of, and no cod-fisheries of any W,fcA.K.Jolm3toii,£thabiir^ fe London. .(■^ o.,^,^ / ■ I LOFOTEN FISHERIES xxxx importance. This theory receives a very- remarkable corroboration from observations of the sea temperatures at Lofoten. The mixture of the two currents could not, from the point of view of the physicist, be a perfect mixture. What would be expected in these regions would be the presence of a number of more or less well-defined currents of different temperatures. The series of observations that have been taken for many years show that this is exactly what obtains at Lofoten, and shows, moreover, that the cod-fish are to be found only in the cold, and therefore presumably Arctic, currents with a temperature of about 5° 0. (41° F.) The Supply of Fish. According to some authorities the cod-fish are practically numberless, and no inroad that man can make upon them is of any moment. Others, again, think that they are by no mealis so numerous, and, indeed, that their total destruction is not improbable if the hitherto reckless slaughter be not checked. With these two conflicting opinions it is rather difficult to come to a conclusion. An absolutely certain conclusion would require a regular census of the cod-fish — to take which would be somewhat difficult. An approximate idea of the matter may, however, be formed from the following facts within our knowledge. The cod do not come to Lofoten in one body, but in numerous separate shoals. This, in all probability, is due to the varying distance the fish have to travel from their homes across the outer bank, the detachments from the nearer colonies arriving at the beginning of the season, while those which appear afterwards have had a longer journey. On the banks these different bodies of fish seem to keep to themselves ; and when the spawning is finished each shoal again makes for its own particular habitat. In the year 1887 it so happened that the weather of Lofoten was exceedingly stormy during practi- cally the whole of the fishing season, and, whether on that account or not, a rather abnormal thing happened : one of the shoals of cod left the banks and entered the Ostnaesfjord in the island of East Vaago. It was a most fortunate occurrence for the fishermen, for they were able to let down their gear in the sheltered waters of the fjord when it was impossible for them to venture out to the banks. The shoal entered the fjord early in January, and as soon as the news got abroad, about 2,500 boats congregated at the spot, and were successful in catching over thirteen millions of fish. This immense number was, however, a mere nothing as compared to the total in the shoal. Ostnaesfjord is an inlet nine miles in length, and on the average one mile wide, and its area may be taken at nine square miles. Over all this, between the depths of sixteen and forty fathoms, the fish were simply packed together, not exactly like sardines in a box, but supposing we allow each fish ten times its bulk of water, then the cubic space would contain ten thousand million. Even supposing that were divided by ten, the number of fish caught, immense as it was, would obviously be far too small a fraction to make any impression whatever on the main body. Now, this was only a single shoal out of the scores, or perhaps hundreds, of shoals on the hcmhs ; for whenever there was a lull in the storm, so that boats could venture out to the open sea, other shoals were found, abundantly, all over the 1,200 square miles of the inner banks, as well as on the extensive banks which lie to the outer side of the Lofoten Islands and are collectively known as Ydersiden. It is, of course, very difficult to form even a rough estimate as to how many shoals might have been present, but certainly the number must have been considerable. Bearing this in mind, and using as a basis for calculation the concep- tion that we have been able to form of the immense quantity of fish in a single shoal, we are left with but one possible conclusion — that the cod comes to Lofoten in numbers which, for all practical purposes, are limitless, and on which all the efforts made by man cannot produce any effect worth speaking about. XXXll THE NORWEGIAN FISHERIES This feeing so, it would be simply purpose- less to impose any limit to the number of fish to be caught in each season. The real fact of the matter seems to be that, amongst the many enemies of the cod, man is of very little account. The female cod-fish produces every year about 100,000 eggs for each pound of its weight, or in other words each average Lofoten ' spawner ' is responsible for a family of 1,200,000 every season. So far as the fishermen are concerned, all these have a chance of becoming mature cod, with the exception of about half a million gallons of roe which they take annually. This seems at first sight a fairly large quantity, and it is in reality more than that yielded by all the other fisheries in the world put together; nevertheless it is a mere drop out of the bucket lofiif^n former average 32 inches in length and 12 pounds in weight, the latter 30 inches and 10 pounds. The liver of the net fish averages \\\ ounces, and of the others 9^ ounces, while the roe and milt weigh 20 ounces and 1 3 ounces respectively. Marked exceptions from these average sizes are rare, but, of course, they are occasionally found. One caught at Lofoten in 1888, and sent by us to the exhibi- tion at Copenhagen, may be taken as about the maximum size of Gadus mon-hua. It measured 4 feet 11 inches in length, over 3 feet in girth, and its weight was rather over 91 pounds. The Pishing. Locality. — In order to understand the modus operandi of the Lofoten fishermen, it will PEOPILE OF SEA-BED ACBOSS THE MOnTH OE THE VESTFJOKD De^cAanneX when compared to the total amount, and were the other enemies of the cod as futile in their efibrts as man, the whole sea fi-om the North Pole to the South, would be choked with them in a few years. Fortunately there is no danger of this, for the ova, the fry, and the fish are being constantly kept within reasonable bounds by an immense multitude of the denizens of the deep, from the whale down- wards ; and the aid that man can give them is to be looked upon, apart from its material results, as a praiseworthy, although perhaps feeble, effort to help Nature in maintaining the ' balance of power.' In aize the codfish vary but little; those caught in nets are, on the whole, somewhat larger than those taken by the hook. The be necessary to give a short description of the Vestfjord, the region where the fish are mainly caught. A glance at the above sketch will perhaps explain the peculiar formation more plainly than words. The deep channel to which we have several times referred sends numberless branches into the mainland, several remarkable instances of which we have already mentioned, such as Hardanger- fjorden, Sognefjorden, and Trondhjemsfjorden. The Vestfjord is another of these deep in- lets, L'unning landwards from the main stem of the deep channel. It separates the Lofoten Islands from the mainland, and cuts into the latter almost up to the Swedish frontier. At its entrance to the Atlantic it is fifty-five miles wide, but of this only LOFOTEN FISHERIES yy-ym ^ the central part is ' deep channel,' the rest being ' banks.' At its outer end the channel is about 200 fathoms deep, but farther on it gradually slopes down to 300, or even 400 fathoms. Its width, at the top, is about nine miles, and it is bounded on either side by- precipitous natural walls, from the edges of which gradually rising banks stretch, on the north-westerly side towards the Lofoten Islands, and on the south-easterly towards the mainland. The channel itself runs nearer the mainland, and its enclosing walls are not equally high: these two circumstances establish a marked difference between the north-westerly and the south-easterly banks. The former, the Lofoten, has at the mouth of the fjord a width of about 30 miles, while the latter, the landward bank, has only 16, both, however, tapering towards the head of the fjord ; furthermore the Lofoten bank is, at the edge of the deep channel, about 150 fathoms below the surface, and thence rises gradually towards the Lofoten Islands; the gradient is, indeed, so regular that if lines representing the different depths from 50 to 150 fathoms were drawn from the apex of the bank, seaward to its base, they would spread out in almost geometrically equidistant rays. The la.ndward bank, on the contrary, forms a higher plateau, the soundings at the edge of the channel being only 30 to 50 fathoms, and the water is, therefore, more uniformly shallow all over this bank. The difference in their formation, and the sea temperatures dependent thereon, are probably the cause of the fisheries taking place on the regularly sloping Lofoten hank, and it is on it only that the cod-fish are found. There are no fisheries on the other bank towards the mainland of Norway. Fishing Operations. — The vanguard of the shoals of cod appears in the VestQord with remarkable punctuality in the first week of January, and the fishermen who reside in Lofoten immediately commence work, and pro- secute the fishing as soon, and often, as the weather permits. The campaign commences by finding out if the fish have arrived, and, if so, where they are. This is done by setting lines, which extend, obliquely, from the surface right down to the bottom of the sea, and when the cod begin to ' attach ' themselves to these lines, not only is their presence ascertained, but also the exact level at which the shoal is swimming. This is also done later in the season, when the track of a shoal has been lost or the arrival of new shoals is expected. By the end of the month most of the fishermen from other districts have assembled, and the fish begin to arrive in increasingly larger shoals ; but they are not in full force before the first week in March, and from that time until the end of the month the fishing is at its best. In the latter part of March the spawning commences, and then the fishing comes, practically, to a temporary stand- still. The cause of this is simply that the fish are too much absorbed in their spawning opera- tions to care for the most tempting bait, or even to move about and so enter the nets. During the process the males separate from the females, not from any sense of delicacy or decorum, but in obedience to a natural law, which has made the ovum of the cod specifically lighter than the sea water. It thus tends to rise towards the surface when spawned. The male fish take up a higher level in the water than the females, and there discharge the milt, by which the ova are impregnated while rising nearer the surface. The spawning occupies only a few days, but the mass of ova and milt liberated is enormous, and sometimes causes the sea for miles around to assume a milky appearance. After some days devoted to spawning, the fish again become lively, and, although they now turn their noses homewards, are quite willing to take the bait or go into the nets. By degrees, however, the fishing becomes poorer, and at the end of April, sometimes earlier in the month, it is brought to a con- clusion. The Lofoten fishery, as we have already b XXXIV THE NORWEGIAN FISHERIES stated, is under Government supervision. The official staff consists of an Inspector-General, one or more judges, about half-a-dozen medical men, and a number of petty officers — in all about- fifty men ; besides several clergymen who are commissioned to look after the spiritual comfort of the fishermen. A grant of about 2,000j. is voted by the Parliament to defray the expenses of this supervising staff. The Norwe- gian Parliament does not generally tighten its purse-strings where the public good is involved, but here its generosity is certainly not con- spicuous. The grant is miserably inadequate, and the result is that the ' superintendence ' of the fisheries is chiefly limited to office work, making out statistical tables, and sending tele- grams, regarding the prospects and progress of the fishing, to the several Ycbts and to the out- side world. Such a thing as maintaining respect for the law on the sea is almost entirely beyond the power of the officials, because the only means of locomotion: granted to them are a few small row-boats, the Inspector-General's repeated requests fot a small steamer having been persistently ignored. The only power which the Government staff have to enforce fishery laws is such as can be wielded from terra firma. One of these prohibits the boats from leaving in the morning until the super- intendent in charge of the Veer flies a signal : this law is made in order to prevent the too enterprising crews from going out ahead of the others and helping themselves to more than their own share of the spoil. Another law pro- vides that all fishing-gear must be taken out of the water on Saturday, and not set again before Sunday evening. This regulation is a concession to the religious feeling of the majority of the fishermen, and^ of course, to their dislike at seeing such as think otherwise profit by their wickedness. It, however, can hardly be enforced by the land-tied supporters of the law, but, never- theless, it is seldom infringed. The would-be Sabbath-breaker knows that the eyes of the righteous will mark his evil deeds and that they will straightway be reported to the inspector, who, unless he can be persuaded that ' wind and weather' did not allow of the lines being lifted, will administer to the sinner his due reward. Directly the signal is hoisted in the morning, each boat makes for the spot where the gear was put down the previous day, and if the haul is satisfactory, the nets and lines are again put down at the same place. Should the catch be meagre, or worse, stUl, if the men draw a ' black net,' as they call it when the silvery glitter of the captive fish is conspicuous by its absence, then it is evident that the fish are going or gonfe, and the question is — where ? Now it is that the Hovidsmand's qualifications are put to the test. The results are in some cases very remarkable — a number of the skippers, over and over again, year after year, know how to choose the exact place, while others search in vain for the fish. This may be experience, or innate instinct, or something else, but not chance — ^that might explain an occasional stroke of luck, but not a long-con- tinued series of successes. Deep-sea Tenvperatwe. — The movements of the cod have always been very puzzling. Some- times the shoals lie deep down and so densely packed that, according to the fishermen, the lead will not sink through them. At other times they spread themselves out in a thin layer at some par- ticular depth ; and so thin, indeed, may this layer be that rich hauls are made from nets and lines which happen to be at that precise depth, while not a fish is caught by tackle set five fathoms deeper or higher. In some seasons the cod will not come near land, but stick to the deep water near the edge of the bank ; in others they come close up to the islands, and may be taken at the depth of a few fathoms. Again, for a period of several years, the shoals chiefly visit East Lofoten and then for a similar period they betake themselves to West Lofoten. Captain Juel, however, is of opinion that probably every season there are fish in plenty at both places, but that there is an apparent scarcity of fish at either the one or the other, simply because there is a scarcity of men to catch them. There is no LOFOTEN FISHERIES xxxr doubt that the fishermen are obstinately tenacious of antiquated opinions. If they think there will be an East Lofoten fishery, there they assemble in great force, and, of course, that year turns out an East Lofoten season as they expected. What fishing there is at West Lofoten may be very good, but the men, like Louis XIV., stick to the principle, j'y suis, fy The causes of the irregular wanderings of the cod have been the object of much specula- tion. One idea suggests that the temperature of the water influences the sudden and unex- pected movements of the fish, and in 1877 Captain Juel, then Inspector-General of the Lofoten fishery, commenced a series of obser- vations of deep-sea temperatures. They were carried on by him every year so long as he continued in ofiSce. The results were rather conflicting, but still, in his final report to the Government, he says that ' the experiences from this winter [1881] appear to confirm the belief that the temperature of the water influences the fishery in a marked degree.' Captain Juel was greatly hampered in these investigations by want of funds. The Govern- ment had some time before spent money on some fruitless scientific researches for the sarrie purpose, but in a biological direction, and they did not feel inclined to give further financial support to anything of a similar nature. The investigations were, therefore, extremely limited; indeed, Captain Juel had only one deep-sea thermometer at his disposal, and that a borrowed one. Comparatively few observa- tions could thus be taken, and scarcely any were obtained at places where the fishing was actually in progress. Captain Knap, who succeeded to the Inspectorate, continued the investigations for a time, but becoming discouraged at the scanty support accorded to him, and the conse- quent barren results, he let the matter drop, his last few observations being taken in 1886. We were naturally much interested in an investigation which might prove to have import- ant practical results on the Norwegian fishing industry, and when informed that the observa- tions under Government auspices were to be abandoned, we determined to take the matter up ourselves, and to work it out in a moro practical way. The results obtained up to this time, and chiefly from the praiseworthy efforts made by Captain Juel, seemed to show that currents of different temperatures were to be found, and that these may change from day to day in direction and in depth, in extension and in form. His tables, for instance, show that on a certain day there was at the place of observation a current of temperature 5°'25 at the depth of 60 fathoms ; next day this current had risen to 50 fathoms, and on the following day it had risen still higher, to 40 fathoms. At the same time another current was running immediately above, and this had a much lower temperature, 1°"75 to 2°-15. It then appeared to us that if these currents, distinctly localised and distinctly differing in temperature, did in reality influence the move- ments of the fish, then there was only one method of investigation which was likely to be successful. If the cod followed by preference a current of a certain temperature, it was clear that the best, indeed the only practical, way to arrive at proof or disproof was to make a long series of observations of the temperature of the water where the shoals were found. If they were more or less constantly in water of a certain temperature, but not in adjacent cur- rents of lower or higher temperature, then we might reasonably conclude that they had a preference for this particular temperature, and — the point of practical importance — that they would, in all probability, be just where a current of the proper temperature was found. This deductive method was obvious, but no attempt had yet been made to carry it out. It required, of course, that the investigations should be made on the spot where, and at the time when, the fish were being caught. We therefore selected one of the most intelligent of the men, the RovidsmaTid, Edvard Meisfjord, b 2 XXXVl THE NORWEGIAN FISHERIES instructed him as to wliat we wished done, and presented him with the necessary apparatus. We further gave him a hint to look out for the fish in water between 4° and 6° of temperature, and then left the matter to work out as an object lesson, in one way or other, for the fisher- men. The event proved our selection to have been a most happy one. Meisfjord took to ecientific fishing with intelligence and with the greatest interest. He regularly found the fish in water from 4°-75 to 5°-25 temperature, and he caught that year no less than 13,000. The following year, 1887, he was equally success- ful, and uniformly hauled in a rich catch, even when boats all round him were having nothing but ' black nets.f This was too much for the other fishermen. At first they had been inclined to sneer at Meis^ord and his instruments and new-fangled ideas, but now they began to see that there must be ' something in it ' after all, and in the following season, 1888, they veered round from scoffers to humble disciples, and taking advan- tage of the formerly despised novelty, they crowded upon Meisfjord's' boat, so that he could hardly get room to set his nets on account of the other boats pushing in, to place their gear in the neighbourhood of his. In the official report of that year's fishery the Inspector-General says : ' A large number of the more experienced and able fishermen are now fully alive to the great importance of this subject, and have become desirous of using deep-sea thermometers. The expense of pro- curing them, however, is more than they can afford, even should their use soon repay the outlay. Much would be gained if, by a grant from the public funds, a few instruments could be provided for distribution amongst the several Veers.' The Inspector also sees now (quite in ac- cordance with our conclusions) that the observa- tions of temperature must be made in combina- tion with the actual fishing. It is rather amusing, further, to notice, that the Inspector places the credit of the ' discovery ' that the fish prefer a temperature of 4° to 5° to the observations made hy the Inspectorate, evidently forgetting that the Government officials, three years earlier, had given up all hope of achieving their object, and had discontinued their investi- gations in despair. The appeal thus made to the public funds was responded to, but not extravagantly. ' The Society for Promoting the Fisheries of Norway ' graciously placed three thermometers at the disposal of the Inspector. These were handed over to three well-known Hovidsmcend, and in the report of 1889, the Inspector-General summarises the results : — ' It seems more and more evident that the temperature of the water plays a very important part in determining the success of the Lofoten fishery, and probably this is a,lso the case in our other large cod-fisheries. The fishermen seem now one and all to have this conviction brought home to them, and requests for loans of thermometers were constantly received. . . . The result of the fisheries this year could not have been so good had it not been for the guide the fishermen had in the thermometers.' In the next year, 1890, the fish happened to come close to land, and the richest fishing frequently took place at a depth of from five to ten fathoms. Thermometers were therefore not used by the fishermen, but the Inspectorate now resumed the investigations they had allowed to rest since 1886. The observations made were but few, and in the report of that year no reference is made to their having been undertaken 'in combination with the actual fishing * ; in fact, the temperature at five to ten fathoms does not appear to have been once taken. This sudden recrudescence of oflBcial activity did not in any way influence the course of observations carried out through Edvard Meis- fjord, and for comparison's sake we may give extracts from some of the reports he sent us. In the beginning of February 1889 he tried the temperature at 60 fathoms, and found it was not higher than 2°-5 to 3°, and he caught only 160 fish. He then moved farther out to a LOFOTEN FISHERIES XXXVll part of the bank where the temperature at 80 fathoms was 4°-5 to 5°, and here he caught 1,100 fish. He was the only one of all the fishermen who tried so far from land, and the others, without exception, had a catch that was very poor. As soon, however, as they learned where Meis^ord had spread his nets they all made for the spot he had selected, and there they ob- tained splendid hauls up to the middle of March. At this time the temperature nearer land rose to 5° at 70 fathoms, and Meisfjord removed his nets higher up on the bank, and again obtained abun- dance of fish ; while at the former place, where the temperature had risen to 6°, no fish were to be had. This lasted for eight days, and then he observed that the conditions again changed. Water of the requisite temperature was again found, as it was from February to the beginning of March, farther out near the edge of the banks, and here, as it is now almost needless to say, a rich fishing was obtained, which lasted throughout the remainder of the season. It is of this year's fishing that the Inspector says, in his report just referred to, that the result of the fisheries could not have been so good but for the use of thermometers. The report received in 1892 contained some additional points of interest, which we may mention. There were very few fish in the Stamsund region of the banks that year, and the temperature of the sea did not rise above 3°'5, with the exception of two nights in March, when 6° was found at 60 fathoms. On these two nights, and these only, the fishing was good. On account of this scarcity of cod in their own particular haunts, the boats from Stamsund Veers had to go West to the Ure grounds. The temperature of the water there was 6°, and the hauls were for some days very good, hut the fish were all milters. On going still farther to the banks west of Ure, where the water is deeper, Meisfjord found 7° ; still farther west, at Balstad, and then at Sund, the sea continued to be very warm : 7° at 70 to 75 fathoms' depth was usual, and no fish were eaught. At length a rising ground, SJtalle, was reached, where at 45 fathoms a temperature of 5° was found. Here the fishing was all that could be desired, and the catch made by Meis- fjord's boat this season yielded about 25Z. to each of the crew.' Another appeal for help made by the Inspector-General to the Government in 1889 succeeded in at last arousing some interest in the matter. A steamer was despatched in 1891 with forty-five thermometers and sundry other scientific instruments. The fishermen received thirty-three of the thermometers, and from the ship a series of observations of the temperature at difierent depths in certain fixed places was made from February 21 to April 13. The next year this was repeated from January 12 to March 28, but the temperature observations do not appear to have been combined with actual fishing, and, as a consequence, the results may probably not be such as to induce the Govern- ment or Parliament to continue the experiment. The results at which the thirty-three fishermen with their thermometers arrived have not been allowed to transpire ; perhaps they are not worth the expense of publication ; but it would be a great pity for a subject so important to mis- carry through a first false step. In contra- distinction to the negative results of the Government stand the conclusions of Meisfjord. He says that -when the favourable temperature is very uniform over a large area, the shoals are more scattered than usual, and therefore more diflBcult to find ; further, he adds that, although a temperature of 5° suits the cod better than any other, shoals of them may occasionally be found in water a degree either warmer or colder, and this he ascribes to the presence of crustaceous food, the very thing to make a cod's mouth water, should he ever feel a dryness in that organ. Fishing Operations {continued!). — To return to the fishermen at work. After the haul has been made and the fish disentangled, the nets are, as a rule, immediately spread again, but at intervals they are taken to land and dried, to ' See note on next page. XXXVUl THE NORWEGIAN FISHERIES prevent them rotting. In the beginning of the season the lines are brought ashore every day to be baited ; but later on, when the days are longer, the same line is often re-set. Lines are distinguished as day-lines or night- lines, according to the time at which they are set. The day-line boats generally leave the shore a little later than the others, in order to give the crews of the night-line boats sufficient time to haul and re-set their gear before the others commence. The latter remain near their lines until they are drawn in the evening, or perhaps leave earlier if fish are plentiful. The net boats and night-line boats go out early in the morning, haul their gear, put either the same or fresh tackle down, and return with their ' As an example of how a fisherman can combine ' practical working with scientific investigations,' I give below one of the tables Meisfjord has sent us. His least successful season has been choseri. Date, 1890 Place and depth Temperatures at depths in fathoms Number offish ' Nets set Hauled Surface 40 60 60 70 90 caught Feb. 8 Feb. 17 50 fathoms .... 2° 5° 4''-5 6° 5°-5 ■ 172 ,,~"l7 „ 18 Vesterkaasa, 40-50 fathoms 2° 2° 4°-5 4°-5 5°-5 5°-5 480 „ 18 „ 19 game place and depth 2° 4°-5 5°-5 313 „ 19 „ 20 »j If 11 • • 2° 2° 4''-5 5° 5°-5 6° 109 „ 20 „ 22 Flat bed, 40 fathoms 2" 2''-25 5° 4°-5 5°-5 512 „ 24 „ 28 East, rising bed, 40-50 fathoms 2''-25 4°-5 5° 6°-5 603 „ 28 Mar. 3 Near Vesterkaasa, 50 fathoms . 2°-25 2° 5° 3°-5 6''-5 4° 5° 67 Mar. 3 „ 6 East, 50 fathoms 2° 2° 3°-5 3°-5 4° 4° 5° 5° 48 ,,"6 -. 7 Moved to another place, 50 f ath. 2° 2° 3°-5 3°-5 4," 4° 5° 5° 37 „ 7 ,> 8 Again to another, 50 fathoms . 2° 3°-5 Te 4° mperatui 5° e not tal ren 82 „ 10 „ 13 Straight off Stamsund, 50 fath. 2° 2° 3°-5 4° 3°-5 5° 4° 4°-5 5°-5 354 ■ „ 13 „ 15 On the edge of the bank, 60-70 f. 2° 2° B°-5 B°-5 4° 4° 4°-5 5°-5 5='-5 159 „ 17 „ 20 Farther out, 70-90 fathoms 2° l°-75 3°-5 3°-5 4° 4° 4°-5. 4°-5 5''-5 744 ,,"20 „ 21 Same place and depth l°-75 3°-5 4° 4°-5 5° 5°-5 287 „ 21 „ 22 A little more east, 70 fathoms . 5° 5° 160 „ 24 „ 25 StiU farther east, 40-50 faths. . 4° 4° 5° 5° 255 „ 25 „ 26 Farther towards FlsBsen, 40-50 f. 4° 4°-25 5° 5° 1,328 „ 26 „ 27 Same place, 50 fathoms . 4°-25 4°-25 5° 5° 1,012 „ 27 4°-25 5° „ 28 11 ,7 » • • i" 212 „ 28 „ 29 Farther out, 60-70 fathoms Tempe 4° irature 5° 384 ,rsi April 1 50-60 fathoms .... not t aken 4"'-5 5° 309 April 1 — 4°-5 5° — ,, 5 jj »»•••• 4° 5° 400 „ 8 ,. 9 40-50 fathoms .... 4° 4° 6° 5° 215 LOFOTEN FISHERIES XXXIX catcli. The time at which they reach shore depends upon how far they have had to go out, and also, of course, upon the weather. If the fish are found in deep water, and consequently close to the edge of the bank, the boats from the Veers in West Lofoten have a longer distance to cover than those from East Lofoten. Some of the former may have to do upwards of ten miles before they reach the fishing ground, and this means that they are unable to return until the afternoon, but when the fish are in the shallow water, close to land, the day's work is over in a few hours. A good catch for a net boat is three hundred to four hundred fish, and for a line boat two hundred ; six hundred to eight hundred for the former, and four hundred for a line boat are very good, and above that rich. Loaded to the gunwale means 1,200 to 1,500 fish in a net boat, and 600 to 1,000 in a line boat. If the catch is too great to be taken on board — 3,500 have been recorded in one haul — the rest of the fish are not disentangled from the net, but, net and fish, dropped again into the water to be fetched next day. Sometimes less successful boats assist in cairying the fish to shore, or if the distance is not far, the fish may be strung on a line and towed to land. The cod is killed by an incision behind the gills, and after it has been split up, the liver and the roe are' taken out and deposited in separate tubs, while the ofial is thrown over- board. This is done, if circumstances permit, , during the return jommey from the fishing grounds, and on reaching the Veer the greater number of the fishermen sell their fish at once to buyers, either on trading ships or on land, principally to the proprietors and storekeepers of the respective Vobts. Some of the men dry, at least part of, their catch by hanging the fish up on long spars resting on wooden sheers. In the course of three or four months they become sufiiciently dry, and are then, for the most part, sent to Bergen whence they are exported as ' dried cod ' {Torfish) chiefly to Italy, Sweden, and Holland. The roe is salted in barrels, and the fishermen usually dispose of it before leaving Lofoten. The heads of the fish are sold to manufacturers of fish manure. The fish sold to the merchant ships and to the proprietors of the Veer are mostly split, salted, dried, and sold as Klvpfisk, chiefly to Spain. The proceeds of the fishermen's toil during the three months in Lofoten do not seem an excessive living wage, but it illustrates, at all events, how a frugal, sober, and industrious race can work — hard and perilous work it is too — and be content with little. The following table gives the average number of fish and gross earnings per man in the last ten years. Tear Number offish Kroner £ ,. d. 1884 1885 1886 1887 1888 1889 1890 1891 1892 1898 612 1,000 1,072 1,070 813 572 1,022 693 540 1,012 215 209 225 163 191 195 245 220 143 225 11 18 11 11 12 3 12 10 9 13 10 12 3 10 16 8 13 12 3 12 5 7 18 11 12 10 Yearly average 840-6 203-1 11 5 10 From this must be deducted the expense necessary to cover wear and tear of gear and boats, cost of board and lodging and of bait. The average for these items amounts to hi. 4s. hd. per man, but in some years, like that of 1892, not a few of the men must have returned from Lofoten poorer than they went. The annual yield of the Lofoten fishery (official district) for the last five years has been : — Tear Numb^ of flah Barrels of common cod- liver oil Barrels of steam-prepared cod-liver oil 1890 1891 1892 1893 1894 30,000,000 21,050,000 16,250,000 27,000,000 28,200,000 32,800 12,700 13,000 17,700 12,100 14,400 15,700 7,000 16,000 10,600 Average 24,500,000 17,660 12,740 xl THE NOEWEGIAJ^ FISHEEIES EoMSDAL Fisheries. Of the two great spawning fisheries, that of the Romsdal is the second in importance, and its main features are so similarto those of the Lofoten fishery that it requires only a passing notice. As at Lofoten, the codfish approach the Romsdal coast in the beginning of the year. They make their way from the sea to the spawning grounds by passing through three deep channels : Bredsundsdybet, to the south ; Boddybet, in the centre ; and Gripholen, to the north; and then they disperse all over the banks, extending from Cape Stadt, lat. 62°, to the mouth of the Trondhjemsfjord, lat. 64°. The fishery district is, for administrative pur- poses, divided into three parts: to the south Sondmore, with the town of Aalesund ; in the centre, Eomsdalen proper, with the town of Molde ; and to the north, Nordmore, with Chris- tiansund. Sondmore is notable as the birth- place of the improved methods of preparing cod-liver oil, for it was in this district, on the island of Giske, that Peter Moller, in 1853,' put up the first factory where the steam process was employed. He soon afterwards removed to Lofoten, but the process he had introduced continued to develop at Eomsdalen, till in 1890 there were no less than fifty-four steam factories established in that district. The yield of the Romsdal fishery is con- siderably less than that of Lofoten, and the following table shows the average results for the last five years (1889-93) :— - Number of fish Barrels of ■ common cod- liver oU Barrels of steam-prepared cod-liver oil Nordmore Eomsdalen . Sondmore 2,086,000 970,000 4,906,000 2,078 1,095 2,822 812 292 4,860 Total 7,962,000 5,995 5,964 ' In an earlier work the writer has named the year 1850 as being the first in which Peter Moller introduced his process ; but as the next year or so was taken up in preliminary experimental work, and the manufacture on a commercial scale not actually commenced till 1853, the latter date is, perhaps, more correct. Maximum and minimum yields were in the same period for the whole district : — Fish Commou oil . steam - pre- pared oil Tear 1892 1892 Maximum 10,700,000 5,570 barrels Tear 1801 1891 1889 Minimum 6,200,000 3,878 barrels FiNMAEK Fisheries. These are divided into four kinds, according to the seasons at which they are carried on : from January to April there is«the Oot or spawning fishery, from April to June the Lodde fishery, from June to September the summer fishery, and during the remainder of the year the autumn fishery. In the first of these only codfish are taken ; in the second chiefly cod, but also a few others ; while in the third and fourth a great variety of fish are caught. The Got Fishery. — In Finmarken as well as at the other parts of the coast of Norway the cod arrive in January to spawn, and leave again in April. They do not, however, come in such enormous shoals as are found at Lofoten, and the fishing is not of sufficient importance to attract men from a distance ; indeed, even the local fishermen do not pursue it to any great extent. The Lodde Fishery. — When the spawning cod have left, the caplin, or Lodde., appear in such enormous numbers that they may, some- times, envelope the coast for fifty or a hun- dred miles, at the same time extending from the shore for many miles out to sea, and so closely packed together that they can be ladled out of the water with a scoop. This of course is a grand opportunity for the larger fish, as the Lodde is small and easily swallowed. Consequently in its walre come shoals of cod, sometimes almost equal to those at Lofoten. These at first have the Lodde all to themselves, except for the whales and seagulls ; but a little later the haddock puts in an ap- pearance, and towards the close of tiie caplin 's stay, coal-fish in great numbers together with PINMAEK FISHERIES xli torsk, plaice, halibut, wolf-fish, and many others join the feast. The Lodde are very irregular in their habits. The great body of them, as a rule, arrive in April and remain to the end of May, but there are many exceptions to this. Sometimes they come as early as December, at other times not before May, and indeed they may not appear at all for years, as was the case from 1830 to 1845. Further they are just as uncertain in re- spect to the places they frequent. Sometimes they go to East Finmarken, while in other years West Finmarken has the benefit of their visit. Sometimes they keep quite close to land, at other times they remain in deep water, or are constantly shifting about from place to place. Their friends, including the cod- and the cod fishermen, of course do their best to follow all these erratic movements, but nevertheless the Lodde fishery is very much like a game of chance — sometimes turning out very profit- able to those who pursue it, and in other seasons resulting in nothing but labour lost. Despite this uncertainty the Finmark fishery stands very high in the esteem of the fishermen. In fact it seems as if the uncertainty was in itself the main source of attraction, and, after all, this is by no means surprising. The majority of mankind are strongly susceptible to the fascinations of the uncertain, as may be seen in the way they conduct not only their pastimes, but also the serious business of life. To this rule the Norwegian fisherman is no exception, as in one way, at least, is shown by his hanker- ing after the fishing lottery at Finmarken. To take part in this he will sacrifice an absolute certainty elsewhere, and at Lofoten we find that it is impossible to induce the men to remain after the arrival of the usual reports of big catches of fish at the opening of the season in Finmarken. The fishing at Lofoten may still remain most productive ; indeed, towards the end it is often at its best ; and the catches in quantity and quality should satisfy, and even more than satisfy, the fishermen. This, how- ever, has no effect, and, no matter how good the fishery may be, the men will not stay, but away they go to try their fortune at Finmarken. They make the journey in the large boats — the Femboringer — and in these they live throughout the fishing, as the accommodation on land is very insufficient. The boats are fitted with a removable deck in the aft-part, and under this the crews manage to find some shelter and rest. From ten to twenty thousand fishermen are present in the season, of whom only about four thousand are local men, and the great majority of the rest come directly from the Lofoten fishery. The tackle used is the handline and the longline, both being baited with caplin. The handline is particularly easy to work here because the fish are often found close to land, and at a depth of only two or three fathoms. On the other hand, when they happen to keep far out and in deep water it is no easy task to haul the heavy cod to the surface. Then also there is a difficulty in regard to bait, for when the caplin remain, say, one or two hundred fathoms down it is impossible to get at them, and herriugs sent from other districts have to be used as bait. Some experiments devised to keep the caplin fresh by freezing have been made lately, but so far as the writer is aware these have not been practically successful. The cod that appear with the caplin are not the same as those which visited the coast in the earlier month of the year for the purpose of spawning. A few indeed may show signs of having recently spawned, but the bulk consists of younger fish not yet ripe for spawning. T5iey are therefore somewhat smaller than the Lofoten cod, and when split they weigh, accord- ing to Capt. Juel, from two to a little over six pounds, whereas in Lofoten the fish are scarcely ever under five pounds, and in some of the Veers they occasionally average as much as eleven pounds. The Finmark fish are distinguished from those of Lofoten by the name Lodde-torsh (caplin-cod) : it is from this that the name of the xlii THE NORWEGIAN FISHERIES fishery — Lodde fishery — is derived, and not, as might be supposed, from the caplin directly. The annual yield of the Lodde fishery for the last five years has been : — Tear 1890 1891 1892 1893 1894 Average Number of fish Barrels of common liver oil Barrels of steam- prepared liver oil 13,652,000 11,868,000 20,000,000 12,776,000 16,322,000 19,740 15,120 28,056 18,156 16,575 1,209 667 3,367 1,793 4,730 14,923,000 19,580 2,351 Summer and Autumn Fishery. — As a rule the caplin finish - spawning at the end of May, and then suddenly disappear, together with the great bulk of the codfish. Still a few of the latter remain and also large numbers of haddock, coal-fish, and torsk. These feed upon the roe left behind by the caplin, and, later, on the fry. The fishing is therefore still continued, and for some time it gives employment to a considerable number of men besides those who live in Finmarken. Soon, however, the outsiders have to return home to attend to the spring work on the little plots of land which they possess and cultivate. About five or six, thousand of those who do not live too far away, generally return to Finmarken after having finished their farm work, and take part in the summer fishery. At the end of July they have again to go home for the hay harvest, which in those latitudes occurs about that time. Nearly eleven thousand men are employed in the summer fishery, and the catches then obtained consist chiefly of coal-fish. The produce of the summer and autumn fishing averaged annually, during the quin- quennials 1881-1885, 13,986 ; and 1886-1890, 9,850 barrels of all sorts of liver oils. xliii COD-LIVER OIL Although we have no record fixing the exact date when cod-liver oil was first used, yet we know that it is a remedy of very respectable age. The Greenlanders, Laplanders, and Es- quimaux were acquainted with its virtues long before they came in touch with civilisation, and during the palaeolithic stage of their exist- ence. The oil used by these primitive peoples was doubtless a very crude product, and the earliest improvement in its preparation with which we are acquainted was dependent upon the introduction of iron vessels. By using these the application of heat was rendered possible, and a much larger quantity of oil was expressed from the livers. This, however, was only a quantitative improvement, and it is very remarkable that, although many cen- turies have since elapsed, the method of pre- paring cod-liver oil remained exactly the same, and not a single step was taken towards im- proving its quality until the year 1853, when Peter MsUer invented and introduced that great advance upon the older method — the steam process of extraction. The Liver. — Before entering upon the details of the modem methods of preparing cod-liver oil, it will be well to give a brief description of the source of the oil — ^the liver of the cod-fish. In size the livers vary considerably, but their average weight may be stated at a little over half a pound,' as, taking one year with another, ' The following figures are taken from our own statis- a hectolitre contains about four hundred livers, weighing abopt 220 lb. A liver of that weight, with its flaps extended, is about 14 inches in tical tables. The first four columns state the number of livers from net- and line-fish required to fill a hectolitre on the first and on the last dayof each year's season.- The other columns show the averages from both varieties of fishing at the beginning, the end, and throughout the whole season respectively : — Tear At the beginning o( the fishery At the close of the fishery l! Is ■5^ Line-flsh Net-fish Line-flsh Net-flsh 1885 1886 1887 1888 1880 1890 1891 1892 1893 1894 450 410 450 315 275 300 395 410 380 500 350 320 412 285 260 245 300 300 285 420 935 650 750 450 550 560 530 500 540 900 630 500 580 395 400 400 378 450 410 625 400 365 430 300 270 280 360 355 330 460 780 575 665 420 475 480 455 475 425 .762 590 470 - 560 360 370 380 400 415 380 611 Average 389 318 637 477 354 661, 462 The last column shows an average for the ten years of 452 livers to the hectolitre, but this is only approximately correct. The averages are based upon the first four columns, and presuppose an equal number of livers from line-fish and net-fish, thus giving a figure that is a little too high. The writer's experience leads him to think that about 400 comes nearer the mark ; but of course there are great variations, as in 1883, when as many as 1,800 livers were required to fill the hectolitre. Net-fish, it will be seen, give larger livers than line-fish, and the livers of both are fatter at the beginning than at the end of the season. xliv COD-LIVER OIL length and about 2^ inches thick at the central part. This is the general size, bat in years, like 1883, when the fish are exceedingly lean, a great number of their livers weigh less than 2 oz. each On the other hand, livers of much larger size are obtained sometimes. The biggest that ever came under our notice was 43 inches long, 6^ inches thick, and weighed over eleven pounds. The liver of the cod-fish, when healthy and fat, is cream-coloured, and so soft that the finger may be pushed right through it without any effort. The leaner the liver, the tougher it is, and its colour deepens to a reddish or even to a nearly black hue. There are always a certain number of diseased liverS to be found amongst the healthy ones. These are recog- nisable by the presence of coloured spots, or by their being wholly or partly of a green colour. Such livers ought never to be employed for making medicinal oil ; but maaufacturers who compete for cheapness cannot well afford to reject them, as their percentage is such as to form a considerable item in the manufacturing account. Like those who are somewhat higher up in the scale of life, the cod-fish has its seasons of prosperity and adversity. In some years they flourish and thrive and produce livers that are real beauties, in others they seem to fall upon evil times, and then their livers are of the lean and ill-favoured variety. ' Seven bountiful and seven barren years ' is one of the many time- honoured sayings which stand high in the fishermen's estimation. It expresses the idea weU enough in a general way, but, like other popular sayings which have the misfortune to condescend upon anything so precise as numbers, it is distinguished by its disagree- ment with dry facts, as may be seen from the preceding tables. The result of this great diversity in the quality of the livers obtained in difierent yeai's is, that at the beginning of each season there is no certainty as to what will happen. This, of course, is very welcome to the speculator. who is always ready to create a panic by hold- ing forth the dread of poor livers. An amusing but by no means inaccurate description of the modus operandi of these speculators was given in the Chemist and Druggist of March 8, 1894, from which we may quote the following: — after some extracts from circulars issued by dealers anxious to dispose of their stock — e.g. ' the reports from Lofoten are very discouraging ' ; ' stormy weather is still prevailing on the grounds and fish are scarce'; 'prices have risen considerably during the last fortnight, and a further rise must be expected' — the journal goes on to give the following sound advice : ' Buyers should remember that year after year the curtain of the cod-fishing melo- drama rises on the horrible entrance of the lean-livered spectre set off by a weird back- ground of elementic wrath only to fall on the apotheosis of the prosperous speculator sur- rounded by the accumulated gains of a prolific oil harvest.' In the previous year (1893) the production of steam-prepared oil had reached the unprecedented figure of 29,254 barrels, a large percentage of which must have been in the hands of speculators at the beginning of 1 894, at the very time when they commenced to work their lamentations. Further, of course, it should be remembered that, whenever there is a deficiency in the Lofoten produce of oil, Pinmarken is ready to fill the gap, as corroborated by the statistical tables already given. Methods of prepwring God-liver Oil in Nor- way. — The primitive method, which is still used to a certain extent, is as follows. As soon as the fishermen reach the Veer, and finish separating the livers and roes, they sell the fish and carry the livers and roes up to their dwellings. In front of these are ranged a number of empty barrels into which the livers and roes are placed, separately of course. The fishermen do not trouble to separate the gall-bladder from the liver, but simply stow away the pro- ceeds of each day's fishing, and repeat the process every time they return from sea, until THE PEIMITIVE METHOD xlv a barrel is full, when it is headed up and a fresh one commenced. This is continued up to the end of the season, when the men return home, taking with them the barrels that they have filled. The first of these, it may be noted, date from January, and the last fi:om the beginning of April, and as on their arrival at their homes the fishermen have many things to arrange and settle, they seldom find time to open their liver barrels before the month of May. By this time the livers are, of course, in an advanced stage of putrefaction. The process of disintegration results in the bursting of the walls of the hepatic cells and the escape of a certain proportion of the oil. This rises to the top, and is drawn ofi". Provided that not more than two or three weeks have elapsed from the closing of the barrel in Lofoten to its being opened, and if during that time the weather has not been too mild, the oil is of a light yellow colour, and is termed raw medicinal oil (Norw. Raa Medicin Fran). As may be supposed, however, very little oil of this quality is obtained. Indeed, as a rule there is so little of it that the fisher- men do not take the trouble to collect it sepa- rately. Nearly all the barrels yield an oil of a more or less deep yellow to brownish colour : this is drawn off, and the livers are left to undergo further putrefaction. When a sufficient quantity of oil has again risen to the surface, the skimming is repeated, and this process is continued until the oil becomes a certain shade of brown. The product collected up to this point is known as pale oil (Norw. Blank Tran). By this time the month of June has generally been reached, and with the wanner weather the putrefaction is considerably accelerated, and the oil now drawn off is of a dark brown colour, and is collected by itself. It is rather misleadingly called light brown oil (Norw. Brun Blank Tran). When no more can be squeezed out, the remainder is thrown into an iron caldron and heated over an open fire. By this process the last rests of oil are extracted from the hepatic tissues, which float about in the oil like hard resinous masses, termed Graxe, and used as manure. In order to fully carry out the extraction, it is necessary to raise the temperature considerably above the boiling point of water. This is well shown by a simple test frequently employed by the fisher- men who, in order to ascertain if the requisite heat has been attained, squirt a small quan- tity of water into the oil, and if it has reached the proper temperature the water is instan- taneously converted into gas with an explosive- like noise. The oil prepared in this way is very dark, almost black, and with a greenish fluorescence in reflected light. In thin layers and by transmitted light it shows a brown colour, and it is therefore termed brown oil (Norw. Brun Tran). Not all the fishermen, however, prepare the oil themselves. Most of them, in fact, are compelled to sell the livers to the shop or store keepers, who supply them with such goods as they and their families require. The reason for this is the system of credit which in these regions has developed almost into a science. The method works somewhat as follows. The local storekeeper supplies the fisherman with whatever he wants, and he in return undertakes to deliver all the proceeds brought back by him from Lofoten the next year. The storekeeper, again, is also supplied on credit by a merchant at Bergen, and on exactly similar conditions. He must bind himself to send to the merchant all he has to sell, and he is not allowed to stipulate any price for his goods. The prices are deter- mined by the merchants of Bergen, who are the real controllers of all this credit system. . They meet together at intervals and fix the prices to be paid for the produce received, having proper regard to the state of the market and, of course, an eye to their own profit. This system works so beautifully that the fisherman who has once got into the grip of the storekeeper can seldom emancipate himself, nor can the storekeeper in his turn fi-ee himself from the control of the merchant. Many of the storekeepers suffer from what may be called xlvi COD-LIVER OIL chronic intermittent bankruptcy. They are continually failing, and by each failure the merchant is apparently a great loser. Curiously enough, he is always ready to give the store- keeper credit again. As this process goes on for generations, one cannot help thinking that somehow it must be a paying business for the merchant, whatever it is to the others con- cerned. In this way the storekeepers are enabled to collect the cod livers from great numbers of the fishermen, and as a consequence they supply by far the largest amount of the raw medicinal oil which comes into the market. The store- keepers and fishermen send almost all their products to Bergen, which is, therefore, the great emporium for cod-liver oil, but none is manufadwred there. When the oils reach Bergen they are set aside for a time in order to allow water and impurities to settle. When this has been completed the oil is drawn off, and such as happens to be deficient in the properties qualifying it for one of the four classes above mentioned is boiled, mixed, and manipulated until it has acquired those properties. Sworn sorters, who are appointed by the city of Bergen, may be called in to decide disputes as to the quality of an oil. They are not bothered with any scientific knowledge, but simply carry out their ana- lysis of an oil by dipping the finger therein, conducting it to the olfactory test organ, and thence, to the gustatory ditto. This, in their opinion, is the alpha and omega of a careful and exhaustive analysis, which being made, they proceed to pronounce judgment. As long as they keep within the legitimate limits of knowledge gained by actual experience, their decisions may be fair enough. Sometimes, however, they afiect to understand more than any experience of this sort can teach, and then the decisions they give pass from the useful to the ridiculous. Up to the year 1853 the supply of cod- liver oil was dependent upon the methods above stated. The late Peter MoUer was intimately acquainted with the primitive methods of making the oil, for many of his younger days had been passed at the fishing places, and in addition he was an enthusiastic student of chemistry, so that perhaps there was nothing very wonderful in his conceiving the idea of how the manufacture of cod-liver oil might be improved. After his method had been made known he was publicly told that ' anybody might have done that,' which, of course, was perfectly true, only nobody did it. Cod-liver oil had been made for centuries, and yet it never seemed to occur to any one of the hundreds of manufacturers that there was an opening for improvement; and, pace those who knew all about it after they had been told, if it had not been for Peter Moller the older methods might have been the only ones up to this present day. But, whatever praise may be due to him for the merits of his invention, his chief claims lie rather in the energy and tenacity of purpose that carried his ideas through the greatest difficulties to universal recognition and appreciation, and for the entire unselfish- ness of his aims. He not only disdained to secure patent rights for his invention, but he freely communicated all the details of his pro- cess, and did all that was possible to make his ideas widely known. Indeed, he actually went further, and endeavoured to encourage and persuade others to adopt and profit by the new method of manufacture: and one of his first acts after perfecting his apparatus was to give away two complete sets — one to Christiansund and the other to Storvaagen in Lofoten. The usual consequences followed. The other manufacturers of cod-liver oil took up an attitude which at its best might be described as armed neutrality, and to this they stuck so long as Peter Moller was struggling to bring his new process into practical use, and to open up a market for its produce, which at first was no easy matter. The buyers, accustomed to the brown oils prepared from putrefied livers, actually refused to believe that the colowrless and THE STEAM PEOOESS xlvii almost odourless and tasteless product of the new 'method could be cod-liver oil at all. It was only with great difficulty that they were convinced ; but when at length it came to be understood that the oil really could be made by a process hitherto undreamt of, and made without the undesirable qualities which for centuries had been supposed to be necessary — because irremovable — evils, then the whole scene changed. The demand for the new oil became enormous, and the in- ventor had the satisfaction of seeing those who had stood aloof when he was bearing the brunt of the battle now humbly doing their best to follow in his wake. Factory after factory was established for the purpose of carrying out his method, and at the present day there is scarcely a nook or corner on the whole Norwegian coast in which one is not to be found.' In 1853, the first year in which the colour- less oil was practically made, the total quantity produced was twenty barrels, and even this small supply was obtained only with the greatest difficulty. It was essential to have the livers in a fresh condition, and, strange as it may seem, such livers were then hardly to be' procured. The great majority of the fishermen were unable to sell any of their produce, as they were bound by the pernicious credit system to hand it all over directly to the store- keepers. The men who were not in the hands of the storekeepers were too conservative to be easily induced to change their customs. Putrid livers had hitherto seemed to them all that anyone could possibly desire, and not even the ofier of temptingly high prices could persuade them to supply fresh livers. Peter Moller was not, however, the kind of man to be baffled > The following table shows the increase of these fac- tories since 1870, nearly twenty years after the new process was first established : — Year 1870 1875 1880 1885 1890 Number of factories 57 73 75 117 148 The above figures do not, however, give a proper idea of either the number or development of the factories, as they do not include factories on board ships, which are certainly very numerous. by a difficulty such as this. He had already over- come many and much moreformidable obstacles, and just as an instance of his determination and energy we may mention that, although he was then a man on the wrong side of sixty, he spent several weeks of the coldest and stormiest part of 1855 sailing in an open boat on the arctic seas in order that he might personally supervise and carry out his plans. Now, all is changed. No one cared to buy any of the original twenty barrels of oil, but at the present day hardly any other kind is in demand, and the production has increased from the twenty barrels of 1853 to an annual output approaching thirty thousand barrels in Norway alone.' Even the fishermen have been taught by experience. They are now eager to sell the livers fresh, and the higher prices which they thus obtain for their produce are helping in a large measure to make them independent of their Mte novre, the storekeeper. Such, in a few words, is the forty years' history of ' a great industry which has been built up in these northern regions,' to quote a recent writer upon this subject. The new method of preparing cod-liver oil which Peter Moller devised and introduced is, like most inventions, a very simple matter — after it has been invented. It is now generally known as the ' steam process,' and the essential difference between it and the older methods is that the oil fwe and sinvple is extracted from the livers instead of the oil mixed with a great * The production in the last six years has been in barrels ( = 231-5 lb. = 25-5 gallons, or 1-158 hectolitre at 15° C.)— - 1889 1890 1891 1892 1893 1894 Finmarken TromsB County . Nordland County : Lofoten . Tdersiden Best of the county . Northern Trondhjem County Nordmbre . Bomsdalen . Sondmbre . 3,686 484 11,140 1,600 27 1,036 3,886 1,209 192 14,421 1,541 691 432 7,264 667 86 15,717 870 20 605 302 4,262 3,367 1,217 6,995 911 1,036 303 4,577 1,793 2,024 16,063 3,942 82 212 691 130 4,317 4,730 1,500 10,632 3,184 ? f 864 302 660 Total . . 21,758 25,740 22,529 18,405 29,254 21,062 xlviii COD-LIVER OIL number of decomposition prothicis. It was these decomposition products that gave the oil what was supposed to be its characteristic brown colour and far from delightful smell and taste. They were derived from the putrefaction of the albuminous constituents of the liver, and it was very natural that they should be supposed to be part and parcel of the oil when that was obtained by leaving the livers until, by putres- cence, the hepatic cells were broken up, and the oil globules in them allowed to exude. The introduction of the steam process, however, showed that these products of putre- faction were not an essential constituent .of cod-liver oil from the chemical point of view ; and from the therapeutical, subsequent experience has' shown that they have nothing to do with the beneficial action of the oil, if indeed they do not detract from it. This last is a point on which the writer would rather not express an opinion, as brown oils are actually used to a certain extent for medicinal purposes at the present day ; but he would ask if, apart from colour, taste, and smell, it is a desirable thing, indiscriminately, to add the ptomaines produced by the putrefaction of albumen, to any medicinal remedy whatsoever. When, therefore, the steam process is carried out with proper regard to its essential principle, the livers must be used absolutely fresh ; indeed, if over twelve hours are allowed to elapse after the capture of the fish, no first-rate oil can be produced from their livers. As soon as the livers are landed, they should be carefully sorted, and all poor, small, bruised, and diseased specimens thrown aside. Those finally selected should be thoroughly cleansed from blood, membrane, and other impurities by washing in several waters ; and, then, after the gall-bladder has been severed, they should without delay be deposited into the melting- vessels. There are three difierent ways by which the melting operation can be carried out. The original method adopted by Peter. Moller was to heat the livers upon a water-bath of large dimensions. The apparatus required for this is now manufactured wholesale in Norway. It is made of tinned iron sheets, and may be pur- chased for less than lOZ. ; a price that places it within the reach of everyone, and that to a large extent explains its almost universal use. Another form of the apparatus consists of double-walled vessels, or jacketed caldrons, which are heated by conducting a current of steam between the external and internal walls. Bach vessel is provided with a self-acting regulator by which the pressure of the steam is controlled to a nicety, and inside each there is a stirring apparatus worked by steam power. This is the form of apparatus that we ourselves employed until two years ago. The third variety is an adaptation for use on board vessels. The liver-receiver is made of wood, in the shape of a truncated cone, with the larger end forming the bottom, the smaller one the mouth, and the steam from a small separate generator is conducted directly into the livers. It is favoured by some makers of the oil because the vessels are able to move from one place to another, dropping anchor wherever there is a prospect of a good supply of liver ; but the ordinary apparatus cannot be employed, as even in the most secure of the harbours there is, at times, too much rolling. Also because it makes the manufacturer inde- pendent of the proprietors of the Veers, who sometimes exact a pretty high rent for permission to erect factories on their ground. The factories on board ship are fairly numerous, but, apart from those referred to, they have no advantages over the factories on land. We have seen it stated that by this method the oil is prepared from fresher livers, because the melting process is performed on board a vessel that can follow the fishermen, and so secure the liver in a fresher condition than the factories on land. That this is impossible should be evident from the description already given of the fishery ; the livers cannot be obtained before they are detached from the fish, and this is done by the fishermen as they are returning from the fishing grounds, and is never completed before the Veer ~ THE STEAM PROCESS xlix is reached ; the livers are then at once sold, and the factories on terra firma have quite as good a chance of getting the liver fresh as those afloat. The practice is for each factory to have its own regular set of suppliers from amongst the boats. Besides, the practical col- lection and preparation of livers in the open sea are too ridiculous to be believed by any except the innocent landsmen. In all the three kinds of apparatus the pro- cess of preparing the oil is based upon the same principle — to force the oil out of the hepatic cells by a moderate heat and in a short time. It is, of course, somewhat difficult to state the minimum length of time which manu- facturers allow for heating the livers, but from hearsay and personal knowledge we believe that it is generally from two and a half to three hours. Of late, however, the oil has been sold BO cheaply that we cannot help thinking that the livers are being heated for a much longer time, in order to increase the quantity of oil extracted from them. When the livers have been exposed to this heating process for such a length of time as the manufacturer thinks most profitable, the oil is drawn off and filled into barrels. The remainder, a thick pulpy mass, is known as Graxe, the liver-rests. By some it is put into bags and pressed, but so quickly does putrefac- tion ensue, that the oil obtained in this way is dark, in colour similar to the light brown or brown oils, and possesses a very rank, unpleasant odour, which is increased with the least delay in the pressing operation. Some manufac- turers, therefore, simply . shoot the pulpy mass into the sea without attempting to get more out of it, even though the oil it contains amount to 9-10 per cent, of the original weight of the livers. When the liver-rests are pressed and the oil is extracted there remaias a dry, compressed mass which is generally either thrown away or sold to fish-guano manufacturers. Even this contains oil to the amount of 25 per cent, of its own weight; but that oil cannot be obtained by mechanical means, and its extraction by other methods would be too expensive to be profit- able. In the first variety of apparatus mentioned above, the temperature cannot, of course, rise above the boiling point of water, so that there is no possibility of regulating it beyond that. In the second apparatus any desired temperature may be reached and maintained up to some degrees above 100° 0. In the third the livers come in direct contact with superheated steam, which is more or less above 100° 0. In respect to the quantity of oil produced by the three forms of the steam apparatus, the second may be made to yield most,' whilst the third gives the poorest result ; but in their rapidity of working the third takes the premier position, while the first variety is the slowest. In regard to the quality of the oil they pro- duce there arises the question. What is under- stood by a first-rate oil ? This is a very com- prehensive term, as the writer has had frequent opportunities of observing. Leaving adultera- tions out of the question, and assuming a ' The oil which we make for sale in barrels (as dis- tinguished from the bottled oil) is prepared in the same way as all the other oil branded ' Finest steam-prepared Lofoten (or Norwegian) Cod-liver Oil,' and, therefore, the following table, taken from our own statistics, may be accepted as showing the percentage of oil yielded by the liver. The table gives our results from the year 1883, which was exceptionally poor, and it shows that with the exception of a single year, 1884, the livers contained a considerably larger proportion of fat at the beginning of the season than towards the end. Average : first Average : last Average : Tear half of season half of season whole season Per cent. Per cent.. Per cent. 1883 23-2 19-8 20-0 1884 43-0 47-0 46-6 1885 50-0 42-0 45-5 1886 58-0 48-0 49-0 1887 46-0 40-0 43-5 1888 54-0 51-0 53-0 1889 540 61-0 52-9 1890 58-0 55-5 57-5 1891 57-6 54-5 56-1 1892 • 55-8 54-7 55-7 1893 57-6 55-2 55-4 1894 47-1 41-3 44-3 1 OOD-LIVBR OIL genuine specimen of oil from Gadus morrhua, no chemical test was known by wMch its good or bad qualities could be determined. Colour, taste, and smell are therefore the only criteria by which an oil is judged. By many, freedom from the so-called stearin is considered an important quality in a first-rate oil ; but this is a questionable virtue, as will be shown here- after; and, besides, the removal of stearin is a sub- sequent operation, so that its presence or absence has nothing to do with the manufacture of the oil. In respect to colour, taste, and smell all the three varieties of the apparatus when properly used are capable of giving equally good results. This, however, is by no means the whole matter, for in addition to the colour, taste, and smell of the oil it has another quality hitherto quite neglected by everybody concerned except the consumers. They also would no doubt be very glad to neglect this quality, but unfor- tunately for them it is far too much in evidence to permit of that being done. When the cod- liver oil has reached the stomach, it sets up, . particularly in delicate constitutions, a series of proceedings known as eructations, or ' re- peatings.' These are far from being pleasant to the patient, and after he has taken the oil for some time, and knows from his unhappy ex- perience the horrors that will certainly follow each dose, he acquires an unspeakable disgust at the remedy. He may indeed force himself to persevere, or he may perhaps be compelled to do so by various forms of persuasion, but in either case, and especially in sensitive, delicate patients, it becomes doubtful in the circum- stances if the game is worth the candle. That cod-liver oil should have such a drawback was obviously a matter very much to be regretted, if not indeed to be ashamed of, in these days of progress. This, at all events, was the view we took of the matter, and it also suggested the long series of practical and scientific experi- ments which we have carried out. These experiments have taught us many things con- cerning cod-liver oil and bodies allied to it which are of no little scientific interest, and which, in addition, are of at least some practical importance. As our knowledge of the proper- ties of fats in general, and of cod-liver oil in particular, was in this way increased, we were gradually led to a more correct understanding of the nature of cod-liver oil from the chemical point of view, which in its turn was the means of explaining the peculiar physiological action of the oil and its special value from the thera- peutical aspect. But this is by no means all, for in addition to these more or less academic results our investigations also led us to a prac- tical result which is not only of theoretical in^ terest but of real importance. This will be described in the section dealing with the new methods of manufacturing cod-liver oil which we have now introduced at Lofoten. Cod-liver Oil from other Countries. — Amongst the cod-liver-oil-producing countries Norway is primus inter pa/res. It is due in part to the fact that the Norwegian fisheries are carried on under conditions which are much more favour- able than any to be met with elsewhere. This alone was sufficient to give Norway the first place, but the introduction of Holler's process gave her another advantage. It effected a com- plete revolution in the methods of preparing the oil, and of course Norway had the lead in the new departure. The improvement in cod-liver oil that was effected by MoUer's steam process, and the consequent very marked increase in the consumption of the oil itself, gave a great impetus to the industry ; moreover, it so happened that Norway was the very place, we might say the one place, where the new process could be carried out to perfection on a sufiBciently large scale. Indeed, the conditions with which nature has endowed that country seem as if they had been specially designed to meet the requirements of MoUer's invention. The consequence of this was that when the new process had been introduced, and had sup- planted, practically, all the older methods of making the oil for medicinal purposes, the advantages already possessed by the Norwegians over their rivals were enormously increased. SUPPLY FROM OTHER COUNTRIES li The steam process, as we have said, requires absolutely fresh materials, and while these can be obtained with ease in Norway they, on the other hand, can be obtained only with difficulty, if indeed at all, elsewhere. The fishing grounds at Lofoten and Romsdalen are situated so near the coast that the boats leaving the Veers in the morning are back again with their catch of fish in the course of a few hours. This makes it quite easy to dispose of the livers before any decomposition whatever has set in. A second advantage possessed by these northern regions is their low temperature ; during the whole of the fishing season at Lofoten the temperature is close to the freezing point. In the fisheries carried on in places or seasons where the pre- vailing temperature is bound to be much higher, the lapse of only two or three hoars, or the exposure of the livers to the rays of the sun for even a shorter time, would be more than suflScient to destroy them ; and therefore sup- posing they could be brought ashore elsewhere, as quickly as at Lofoten and Romsdalen, still no first-rate oil would be obtained from them. A third advantage of the Norwegian fisheries is the large supply of raw material available. It is quite impossible to carry on a steam factory unless an abundant supply of livers can be constantly obtained, and this of course is possible only at fishing centres to which a great number .of boats resort, as is the case in the Veers of Lofoten and Romsdalen. These are the three conditions which are abso- lutely necessary for carrying out the steam pro- cess of preparing cod-Uver oil. Where even one happens to be absent the successful manufacture of the oil becomes very difficult if not altogether impracticable, and we may add that, so far as we are yet aware, with the single exception of Norway, these three essential conditions will hardly be found existing together in one and the same place. We ourselves have carried out a special and detailed investigation of the capabilities of most of the European districts where cod fisheries of any importance are to be found, and in all we have been met by the same insurmountable difficulty — the absence of one of these three conditions without which the first-class oil cannot be produced. Iceland. — According to the reports furnished to us by Mr. Heyerdahl, who visited the country for the express purpose of carefully investigating its capabilities for the production of cod-liver oil, the fisheries of Iceland are, on the whole, very similar to those of Norway — with the exception of one condition. This is the third of our three essentials — the supply of a suf- ficient quantity of fresh livers to keep a steam factory going. Of course the total quantity of cod liver obtained in Iceland would be sufficient to supply a large number of factories, but unfortunately it cannot be utilised because it cannot be brought together at any one point in sufficient quantity while it is yet fresh. In the case of a steam factory where Moller's pro- cess is properly carried out the available supply of liver is just that supply which can be col- lected in an absolutely fresh condition ; and as it seems practically impossible to obtain such a supply anywhere in Iceland it follows that we cannot expect that country to produce any steam-prepared cod-liver oil of the best quality. Some years ago an English company erected a factory at Njardvik, in Iceland, but in a very short time it was abandoned. This was a prac- tical demonstration of the correctness of the con- clusion at which we had already arrived, for the factory had to be given up simply because a sufficient supply of fresh raw material, at pay- ing prices, could not by any means be got together. The reason for this is to be found in the conditions under which the fishermen in Iceland live. In addition to their occupation as fishermen they are, almost without excep- tion, also farmers. The plots of land which they cultivate are situated up country, and when the fishing season arrives, they come down to the fjords, but do not congregate at any special centre as in Norway ; their fishing huts are scat- tered all over the shores of the fjords, and each man conducts operations from his house ; from c2 Hi COD-LIVER OIL this he sails out and catches whatever fortune happens to ' bring to the net,' with this he returns to his house, and if anyone wishes to have the livers from the fish caught they must go to him for them ; it becomes therefore a practical impossibility to secure fresh livers in any reasonable quantity. The better kinds of even the common oils are not produced by the Icelanders, but only the brown oil — exactly the same as that made by their forefathers in the year 1000 or thereabouts. They are not a people who take kindly to modern ideas, and they resent the advice of outsiders, how- ever well meant it may be, and this not only in regard to the way of making cod-liver oil. North America. — The writer has no personal knowledge of the fisheries of the United States, Canada, or Newfoundland, and has not been able to find any reliable literature sufficiently exhaustive to give a proper idea of the cod- liver-oil industry in those countries. There are a few steam factories working at some of the seaside towns of Massachusetts and Maine, but their products cannot bear comparison with the best Norwegian oils — so far as can be judged from what has been found at various exhibitions. The bank fisheries of America, being conducted far from land, and in the hot summer months, cannot supply the fresh livers required for steam-prepared oil. The off-shore fishery, how- ever, occurs in winter, when the spawning fish visit the coast, and should furnish proper raw material for an irreproachable oil. Why it does not is not apparent to outsiders. British Isles. — The production of the best variety of oil in England is not practicable except in very small quantities, and on re- latively rare occasions. Nearly all the cod-fish are sold fresh for immediate consumption, and as the livers are disposed of together with the fish they are not available for making cod-liver oil. Further the chief fisheries are on the banks in the North Sea, and therefore too far from land, and the winters are, as a rule, too mild for the proper working of the steam process, even were it possible to obtain a supply of material from the off-shore fishery. Russia.— Theve is only one other place in Europe where cod-liver oil is prepared — that is, Eussia — on the seaboard stretching from the Norwegian boundary towards the White Sea, and known as the Murman coast. About a dozen Veers are scattered along this district: they are small, far apart, and miserable as harbours. The Russian fishery is not, therefore, of much consequence as a source of steam-prepared cod- liver-oil supply, except in those rare years when the Lodde fishery in Finmark happens to. be a failure, which occurs only when the caplin do not visit the Norwegian coast, but for reasons unknown go farther east, to the Murman coast. In former times when this took place the Norwegian fishermen used to betake themselves to the Russian coast, but recently they have been forbidden to fish there, although the fishermen from that country had always been allowed to pursue their calling without let or hindrance in Norway. This rather selfish proceeding on the part of the Russian authorities has not, how- ever, turned out to their advantage, for it has resulted in the practical destruction of their fishery as a source of medicinal cod-liver oil ; and our factor, Mr. Ostensvig, who visited and reported upon the region a few years ago, found only a few small steam factories in operation, and their produce was neither large nor good. The caplin never goes east of the Veer known as Korabelnaja, and all the Veers farther east, that is, from Feretika to Litza, close to the White Sea, are utilised only for the summer fishery, when coal-fish and halibut are taken, but scarcely any cod-fish. Adulterations of God-liver Oil. — As will be seen from the above, Norway has practically a monopoly of the steam-prepared cod-liver oil. No other country has the same advantages for carrying out the process properly, and if these advantages are fully utilised it is but natural that Norwegian oil should hold the field. Certainly the oil produced under such favour- able conditions ought to be the very best, and ADULTERATIONS liii on the whole it has attained a standard of which the Norwegian manufacturers have every reason to be proud. But, nevertheless, there is no doubt that latterly there has been a noticeable tendency to deterioration of quality even in Norwegian oils. The reason for this is not far to seek. The steam process requires conscientious working ; anything that is gained in quantity is always lost in quality, and the low prices which have ruled of late years have been a strong irducement to squeeze more and more oil from the livers, and not to be over particular as to their quality, or even as to the kind of fish from which they are taken. At Lofoten and Romsdalen the use of livers other than those of the cod is out of the question, because no other fish are caught there ; but in regard to the selection of livers of proper quality the less said the better. In Finmarken the matter is entirely difierent. The making of cod-liver oil goes on all the year round, but except during the unimportant spawning fishery the livers of codfish are by no means the only raw material available for the caldron. Great quantities of haddock, coal-fish, hake, torsk, ling, halibut, and wolf-fish are caught, and last, but not least, there is the porbeagle and the Greenland shark — a single liver of the latter being often equal in bulk to two barrels of cod's liver. The Pinmark manufacturers are thus subject to a temptation which does not exist at Lofoten or Romsdalen, and whilst, without doubt, there are honourable men amongst them, there are also others who are afflicted with a singular inability to distinguish between the livers of the cod-fish and those of other fish. Their ideas as to what constitutes cod liver are not unlike the rule laid down by the railway porter regarding dogs : ' Oats is dogs, and rabbits ia dogs, and a parrot is a dog.' This confusion of ideas is, of course, most marked in years of scarcity, and when the writer has happened to be in Pinmarken at such seasons he has himself seena nything that could possibly serve as an apology for a cod liver thrown into the caldron, shortly afterwards to emerge as purest Nor- wegian cod-liver oil from carefully selected livers! These remarks do not apply to the oil made in Pinmarken during the Lodde fishery — at least in ordinary years. By far the greater number of the fish taken at this particular season are cod. There are frequently, also, considerable quan- tities of haddock, but of other fish there are very few until later in the year. The circum- stances, therefore, do not allow of much adul- teration before the end of the Lodde fishery. The only possibility of any importance is the addition of some haddock-liver oil, and it is Eot so objectionable as the other varieties. Indeed, in appearance and taste it can quite compare with cod-liver oil, but of course its therapeutical value is quite another question. Bleaching in the sun is a process that is used for two distinct purposes. It is resorted to in order to improve the appearance of first- class oils. The oil is naturally a very pale yellow, on account of the presence of a pigment, lipochrome, concerning the chemical nature of which almost nothing is known. Like most organic pigments it is destroyed by the action of the sun's rays, and therefore good oils are sometimes bleached as if to make them look better than the best. If this is done very care- ■ fully at a low temperature, and never extended beyond a couple of hours, possibly no great harm may result. In the opinion of the writer, however, it should never be attempted, because the bleaching process not only destroys the lipochrome but also promotes decomposition of the oil itself, and the formation of products which are useless therapeutically, and may in addition irritate the stomach and disorder the digestive processes. An oil that has been bleached in this way can always be detected, at least by the experienced. It may, indeed, be perfectly colourless, but has a certain dull, faded appearance, due to the loss of the re- fractive power, which gives the unbleached oil a characteristic brilliancy. The attempts to decolourise good oils are decidedly objectionable, but a much stronger liv COD-LIVER OIL term would be required for the second purpose for which bleaching is used — decolourising inferior steam-prepared oils in order that they should pass as first-rate products. The darker colour of such oils is not caused by the presence of lipochrome, but of decomposition products formed from the liver either before or during the process of preparation. The sunlight, which destroys the lipochrome, will at the same time form coloured decomposition products from the livers, probably from some of their albu- minous constituents, and if they have been ex- posed to its rays for a couple of hours no really good oil can be produced from them. The same result follows when the livers are kept too long, or when the temperature is high, and also when during the melting process .the livers are heated too long or too much. Now, most unfortunately, it happens that after the removal of the albuminous substances, these colouring matters can be destroyed by the further action of the sun's rays, and, provided the oil is not too dark, it may be bleached so as to resemble a colourless and therefore, as some people suppose, an irreproachable oU. As a matter of fact an oil doctored in this way is infinitely worse than the worst specimens of brown oils. These are honest productions, having no pretensions to be anything except what they really are, whilst, on the other hand, the oils artificially made colourless profess to be first class, and yet con- tain, not only their original, though decolourised, decomposition products, but, in addition, all those formed during the bleaching process. The above account covers all the sins of the Norwegian makers of cod-liver oil. They may not always be so particular as they ought to be in selecting livers that are perfectly healthy ; they may occasionally use livers that never grew inside a cod-fish ; they may try to get more out of the livers than they should get ; and they may attempt to improve the appearance of their oil by bleaching it; but the writer can say with confidence that this is all ; and that no Norwegian manufacturer adulterates his oil with animal products other than those men- tioned, or with vegetable or mineral oils. The writer ought, however, to make one proviso — that his statements apply only to Norwegian oils as they exist in Norway. When they leave the land of their production the makers, as a rule, cease to be responsible for them. Most of the oil is sent to Hammerfest or Bergen, and thence exported to Hamburg, London, or New York, where it is sold and lost sight of until it again appears, often in a beautified form, and labelled 'virgin drippings,' 'first grades,' ' from carefully selected livers,' ' pre- pared by an entirely new process,' &c. Iv PETER MGLLER'S NEW PROCESS Cod-liver oil is undoubtedly one of the most valuable medicinal agents known to man. Its value has one remarkable proof in the fact that it was extensively used in the days when only the brown variety could be obtained. In those days cod-liver oil was not a desirable article of consumption ; indeed, to put the matter plainly, it was an abomination, and no one could have taken it willingly, even once, not to speak of day after day and month after month. Nevertheless many people did take it, and the only reasonable explanation is that the oil must have given strikingly favourable re- sults; otherwise, medical men would not have been justified in prescribing it, nor could their patients have been induced to use it. But although cod-liver oil was thus highly esteemed, despite its very objectionable cha- racters, these, there is no doubt, were a great drawback to its successful administration. The class of patients to whom the oil is given, or at all events to whom it is useful, are cases with, broadly speaking, defective nutrition, and, there- fore, exactly the cases which can least afibrd to risk any disturbance of the digestive apparatus. Yet this was the very thing that the old, badly prepared cod-liver oil was most apt to do. It was not only disagreeable to the palate, but it was also intensely irritating to the stomach, and often it must have been a question whether its administration did not do more harm than good. These highly objectionable characters of the old cod-liver oil were due to the fact that it was not the oil pure and simple, but the oil with something added to it. This something was the cause of the greater part of the trouble, and, not to mince the matter too finely, it was nothing more or less than an extract of rotten livers. The oU was obtained in those days simply by allowing the livers to putrefy, when the decom- position of the albumens resulted in the break- ing up of the cells, and the escape of the oil globules contained in them. It also, however, resulted in the formation and inclusion in the oil of a large variety of putrefactive products, part of which has recently been found to consist of poisonous ptomaines. These, even up to the present day, are called, ' active principles ' by some people, but we need hardly add that an admixture of poisonous ptomaines, both quantitatively and qualitatively uncontrollable, is not a desirable addition to any medicinal remedy, and perhaps least of all to cod-liver oil, seeing that it is much more a food substance than a medicine. If they are present in the oil they render it not only disgusting to the patient, but they also make it quite as likely to hurt as to help him. A generation or two ago the brown oils were the only kind that were made or that could be obtained, and the people of the present day who have to take cod-liver oil may be thankful that, in regard to this at least, they live in happier times. All the disagreeable and detrimental qualities of the oil due to decom- posed albumens were removed by the introduc- tion of Moller's early process. The livers were no longer left to rot till the oil exuded, but the oil was drawn off from them while they were yet perfectly fresh. Putrefactive products were, of course, an impossibility in oil made in Ivi COD-LIVEE OIL this way — provided the process was properly carried out. The real cod-liver oil — that is, the oil with- out the extract of rotten livers — was clear in colour, practically free from the nauseating taste and smell, and consequently, in com- parison with the old oil, it was a thing of delight from the consumer's point of view. From the doctor's point of view it was also an improvement of no small importance. Not only could it be given without upsetting the patient, but in addition it was cod-liver oil pure avd simple : its therapeutical effect could now, and for the first time, be obtained in its greatest perfection and to its fullest extent, and this without any drawback whatsoever — except one. Peter Moller introduced his invention in 1853, calling it, with characteristic modesty, not by his own name, but simply ' the steam process of preparing cod-liver oil.' The colour- less oil produced by it was so completely different from the brown oils then in use, that there was no small difficulty, at first, in getting people to believe that it was cod- liver oil at all. But as soon as they became convinced that it was really so, the advantages it possessed were so great and so obvious that in a few years it was practically the only oil in use. The product of the steam process was thus a vast improvement upon the older oils with their putrefactive ptomaines and their sickening taste and smell, but it was not per- fect. The advance made by Peter MoUer's invention was so great that no other improve- ment in the manufacture of cod-liver oil can possibly equal it ; yet the oil produced by it is capable of a considerable alteration for the better. The new cod-liver oil had indeed lost the objectionable taste and smell of the old oil, but it still retained one objectionable character, and that one perhaps the worst of all — the property of causing nauseous eructation. This most disagreeable symptom has seemed to be more or less inseparable from even the very best steam-prepared oils, and Heyerdahl's in- vestigations have shown that it is dependent upon certain chemical bodies which cannot from their nature by any possibility be elimi- nated from the oil though prepared by means of Mailer's original process. The disagreeable taste and smell of the older oils were, as we have said, due to decom- position products derived from the putrefaction of the livers; but the constituents causing eructation are derived from quite a different source. They are not broken-down albumens, but oxidised fats — products derived, in fact, from the oil itself. Some oils contain such products in a fully developed form : these are rancid oils. Other oils contain them in a more or less potential form, and these may be almost tasteless, till they reach the stomach, when they immediately become quite otherwise. Now, an oil distasteful to the palate is certainly bad enough, but not nearly so bad as an oil which, although, perhaps, tasteless when taken, may become unspeakably abominable when it reaches the stomach. Why it becomes so is easily ex- plained : such oils do not remain passive in the stomach, but the irritation they produce sets up eructation and brings the taste up to the mouth, where it asserts its unwelcome flavours, not once only, but again and again, till the un- happy patient may be completely upset and firmly convinced that if it is to be at the ex- pense of taking cod-liver oil, life is not worth living. Such a conclusion Sts this is not unfrequently come to by patients who might be greatly benefited by cod-liver oil, while others — those who force themselves to take the oil — do so only by a great and, from a medical point of view, very undesirable effort. Thus, for both classes, this remaining drawback is a serious one, and its removal is a matter of no little importance to them, and to all who are interested in cod- liver oil. Many attempts have been made to remove it, but up to the present without success. In fact success was not possible where the efforts were misdirected : these attempts, so far at least as they have come PETEE HOLLER'S NEW PROCESS Ivii under our observation, have been made under an entire misapprehension of what had to be done, and therefore in an entirely wrong direction. We cannot here enter into all the details of these well-intentioned efforts, as they are discussed in another section of this work, but, generally speaking, they aimed at the production of an agreeably tasteless or pleasantly flavoured preparation of cod-liver oil. The eructation-producing property of the oil need not, however, have any connection with its taste, unless present in a high degree, and consequently these preparations were not likely to be successful. As a matter of ex- perience they have not been so, and their highest achievements have been to make the oil agreeable, or at least not disagreeable, to "■the palate. This may be a laudable result in itself, but it is to be noted that it is so only in regard to inferior oils, for an oil properly pre- pared by Moller's method should have no un- pleasant taste, even to the most fastidious. We have not been unmindful of the im- portance of the question, and have not been altogether idle ; indeed, we feel under an obligation to do everything in our power to solve it. The late Peter Moller devoted the best part of his life to the task of improving the methods of preparing cod-liver oil. The pro- cesses he invented and introduced constituted the only real advances which have been made in the matter and were an immense improve- ment in the oil ; from being the crudest pro- duct it became, with the exception of this single d/rawlach, the most perfect product imaginable. The efforts made by Peter Moller did not suc- ceed in removing the drawback, and the least that we, his successors, could do was to take up his nearly, but not quite, finished task and endeavour to bring it to its legitimate and suc- cessful conclusion. Practical experience had convinced us that the taste of cod-liver oil had not necessarily anything to do with its property of disordering the stomach and causing eructation. The evil taste and smell of the oil prepared after the old methods were due to the putrefactive pro- ducts thereby added to it, and when these were absent the oil might have been absolutely with- out taste or smell — but still capable of causing eructation. It was thus evident that all the efforts made to overcome this difficulty by covering the taste of the oil were quite beside the mark. Of course, the taste of the oil when taken in no way influences the taste of the eructations, and no matter how pleasant the former maybe made, the latter will' be quite different. Our early efforts were directed to bringing the steam process to its fullest perfection, and, although they did not fully lead to the desired object — an oil which would not cause eructation — they certainly did teach us two things ; first, that it is of no use whatever to try to improve the oil once it is made, and consequently that the improvement must be in the man/ufacturing process ; and secondly, that the oil which has been exposed to the lowest possible h&at for the shortest possible time possesses in a lesser degree the ob- jectionable quality. But to produce an oil en- tirely free from the tendency to cause eructation seemed quite impossible, and it was asserted that this property was essential to the oil — part and parcel of it, in fact. We did not forget that before the intro- duction of the- steam process exactly the same statement had been made regarding the brown colour and objectionable taste and smell of the oil, and therefore the prevailing opinion was not permitted to influence in any way the efforts we were continuing to make to overcome this remaining difficulty. To minimise the objectionable quality we, in the meantime, laid down the rule that the livers were n^t to be svijected to a temperature exceeding 70° G., and even that for only 45 minutes. Of course this proved a costly method, because the quantity of oil that exudes during that time and at that low temperature is comparatively small, and the result was that many manufacturers found themselves unable to keep to this standard. Indeed the low prices Iviii COD-LIVER OIL to which cod-liver oil has been brought by absurd competition, and unjustifiable methods of production, have made such a standard impossible for makers who find that cheapness is a necessary element required to obtain a market for their oil. Apart from its costliness, however, the process, even in its highest perfection, was not entirely successful, and in the year 1880 we became convinced that everything had been done in this direction that could be done, and that our object could only be attained by striking out in am, entirely new direction. This was accordingly done, and with results which we now wish to bring before all who are interested in a matter of such importance. Until about fifteen years ago the chemistry of fats was practically an unexplored field, and none of our present more exact methods of examining and analysing these bodies was then available. This was the first difficulty that con- fronted us when we came to the conclusion that having exhausted the a/ri, we must fall back on the science, of preparing cod-liver oil. We did not, however, allow that to deter us from carrying out the plan upon which we had determined, and we are able to state now that, in regard to cod-liver oil at least, the difficulty of scientific analysis is greatly minimised. The knowledge of the chemistry of fatty bodies has immensely increased since 1880. Many investigators have devoted themselves to this particular department of chemical science, and the results which they have obtained are not only of great scientific interest, but many of them are of equally great practical importance. In the y«ar 1857 Peter Moller, in a paper * read before the congress of Scandinavian scientists at Ohristiania, expressed his opinion that the fatty acids of cod-liver oil difier essen- tially from the fats derived from other sources. As time went on this opinion was, more and more, confirmed by the marked difierences ' Om Tilvirkningen of TorskeUvertran i Ahninde- lighed og om en my Maade for TiTmrhmngen of Medicm- tran, ChrisUcmia, 1857. which our investigations revealed between cod-liver oil and oils containing the ordinary fatty glycerides, the characters of which were, however, pretty well overlooked by analytical chemists. Holler's opinion was only an opinion, and at that time incapable of scientific demon- stration ; but the progress of organic chemistry has shown that he was, nevertheless, perfectly correct. The iDvestigations commenced by us in 1880 have been directed chiefly to clearing up the problems connected with the chemistry of cod-liver oil and the other oils allied to it, and this work has been conducted by Mr. P. M. Heyerdahl. To his enthusiastic and unwearied eflforts not only we, but all who are interested in the subject owe a deep obligation. The results attained by him stand facile princeps amongst the many notable additions made during the last few years to our knowledge of the chemistry of fats, and, so far as they bear upon the nature of cod-liver oil, they are simply the scientific corroboration of Peter Holler's expressed opinions. What they have shown and proved is briefly this : the acids which form ordina/ry fats — that is, the acids of olem and stea/rin — do not exist in cod-liver oil, but there are instead, at least, two glycerides, which so far have not been found anywhere else. Apart from its scientific interest, the prac- tical importance of this discovery is so obvious that we need not insist upon it. It throws the first real light on the nature of cod-liver oil, and enables us to comprehend how that oil pos- sesses a pecidia/r physiological action not pos- sessed by other oils, and thereby exercises a therapeutical influence which is sui generis. These new fatty acids have been named therapic acid and jecoleic acid. Their properties, from the chemical point of view, have been as far as possible investigated and determined, and the results show that, compared with the ordinary fatty acids, these bodies possess several remarkable and very suggestive characters. Therapic acid is a compound with four double bonds, and consequently it belongs to the PBTBE HOLLER'S NEW PROCESS lix tetra-ethylene series, of which it is the first and only representative as yet discovered, not only amongst the fatty substances, but, indeed, amongst any chemical compounds. This is certainly a most remarkable fact, and at once suggests the possibility of essential differences, physiological as well as chemical, between therapic acid and the other fatty acids. It is also an inter- esting circumstance that therapic acid is the only member of the margaric acid group which has yet been found as a product of living animal nature. In addition to its chemical constitution, therapic acid is distinguished by the astonishing facility with which it attracts, and is split up by, oxygen, iodine, bromine, and other agents, even at ordinary, and still more at higher, tem- peratures. In his investigations Mr. Heyerdahl found it absolutely necessary to protect the acid from the inroads of oxygen, which was done by con- ducting all the analytical processes under a current of hydrogen. The instability of the acid defeated all attempts at isolating it in the uncombined form, but the bromine combination product in which the unsaturated compound is transformed into the saturated octa-bromo- margaric acid was found to be sufficiently stable for closer examination, and through it the chemical constitution of the acid was investi- gated and determined. Apart from the scientific interest of this discovery, it was of immense practical import- ance to have determined the presence in cod- liver oil of a fatty acid so very unstable in its nature. This indeed gave us the key to the problem we had been endeavouring to solve, pointing out to us both the cause of the eructation prodntcing property of cod-liver oil, and the general direction of the steps necessa/ry to remedy it. Methods devised to give an exact quantita- tive analysis of the hydroxylated therapic acid present in cod-liver oil made it possible to esti- mate the bearing of these hydroxy-acids on the production of eructation, and it was found that the hydroayy-aoids were the cause of eructation, and that this unpleasant symptom was more or less man-lied according to the quantity in which they were present. Ood-liver oil containing no hydroxy-acids caused no unpleasant eructation whatever. The rapid oxidation of the fatty acids of cod-liver oil was strikingly brought out by a difficulty that arose during Heyerdahl's first attempts to estimate the amount of hydroxy- acids in the oil. No constant results could be obtained, and even samples taken from the same parcel of oil gave results that were sometimes utterly divergent. When a careful comparison was made of the long series of estimates, he found that, other things being equal, the more time an analysis occupied, the more hydroxyls there were. This could be ascribed only to a very rapid oxidation of the fatty acids when ex- posed to the air during the analysis, and the lesson taught thereby, in regard to preparing the oil was obvious. When the process of estimation had been perfected, so that absolutely reliable results could be obtained, it was ascertained that even the very best steam-prepared oils contained hydroxyls, their acetyl value being about 2 ; which corresponds to 0-15 per cent, of hydroxy- acids. This was the minimum obtainable by the most careful application of the steam process and the slightest increase of time during which the livers were exposed, or the use of even slightly higher temperatures, caused a marked increase in the acetyl value of the oil produced. Ood-liver oil with an acetyl value of only 2 may cause marked eructation, and it was evident that, even at its very best, the steam process was in this respect a partial failure : it could not give an oil sans pewr et sans reproche. But Heyerdahl's researches had now clearly shown us that this was not an inherent property of the oil, as formerly believed, and that an oil entirely free from this mischievous quaKty might be produced. If during the process of manufacture the fatty acids of the oil were never allowed to come in contact with oxygen, the oil would be absolutely free from the Ix COD-LIVER OIL objectionable hydroxy-acids, that is, free from the one practical difficulty that yet etood in the way of administering cod-liver oil. The oil carefully prepared for experimental purposes under a current of hydrogen did not contain a trace of hydroxyls. It was, in fact, cod-liver oil pure and simple, and the first that had ever been seen ; for, everything produced before had contained, not only the pure fats of the oil, but also in greater or lesser degree their oxidation or decomposition products — the hydroxy-acids. From the chemical point of view we had now reached our ideal oil, a/nd a series of careful easperiments satisfied us that from the physiological point of view it was also the ideal — an oil incapable of causing irritation of the stomach and, consequent, eructation. This result, answering our most sanguine expectations, and justifying the years of work that had led up to it, was certainly most gratifying to all who had looked and laboured for it, but it left us with another problem to solve before we could practically realise our object. To produce this perfect oil in very small quantities for scientific purposes was now, comparatively easy ; to pro- duce it on a commercial scale was altogether a difierent matter. This last and only remaining obstacle necessitated many ex- periments, naturally accompanied by many failures, but at length the difficulties were overcome, and we were successful in devising an atppajratms hy which we could produce cod-liver oil on a la/rge scale without allowing even the slightest oxidation to take place. The apparatus even- tually adopted is so designed that the air can be completely excluded from it during the whole operation from beginning to end, the process being conducted in a current of carbonic acid from the moment the livers enter the apparatus until the oil obtained from them is safe within the bottles.' We have subjected the oil obtained by this process to a series of most carefully carried- out investigations, with results so excellent and so uniform that we are perfectly satisfied that at length our object has been attained. For years our investigations, whatever their value from the scientific side, were, from the practical aspect, of little value when compared with the results of to-day. The product, the Hyd/roxyl-free God-liver Oil, seems to all intents and purposes perfect — without either the peculiar smell or oily taste, and without that most obnoxious of all the real or imaginary characteristics of cod-liver oil, the property of causing loathsome eructation ; and we do not think that we go too far in saying that IT IS THE FIRST AND ONLY REAL IMPROVE- MENT IN THE METHOD OK MANUFACTURING COD- LIVER OIL SINCE 1863, WHEN Peter MOller INTRODUCED HIS STEAM PROCESS. ' The method has been protected by letters patent in the different countries. bd PHAEMAOEUTICAL ANNOTATIONS A volume of no small extent might be written on the pharmacy of cod-liver oil, for that unfortunate article has been ' prepared ' by methods which are only as numerous as, in the opinion of the author, they are uncalled for. Many of these methods are now matters of history, but, of course, each was supposed to be an improvement on the oil itself, although in some cases going so far as to improve it out of existence. A full account of all the past and present ways of pharmaceutically preparing cod-liver oil is here out of the question, and all that the writer will attempt shall be a brief description of some instances of the more interesting or more important methods that have been used. Plavoukings Before the introduction of ' elegant prepara- tions ' of cod-Uver oil, that is, in the period when the light-brown varieties had full sway, it was found desirable, if not indeed necessary, to cover the taste of the oil by adding various flavouring agents. After the steam-prepared oil had practically displaced the darker kinds the practice was continued, and still is, although as a matter of fact it should be quite unneces- sary — if the oil be pure ayid properly prepa/red. Some of these flavouring agents or corri- gentia are very curious and interesting, and we may here give a brief selection of them. As far back as 1775 it was found difficult to make the patients in Manchester Infirmary swallow the light-brown oil ; and we are told that the vehicle in which they most preferred to take it was warm beer (^BriUsh and Colonial D. vol. xxii. p. 453, from Med. Press — Hutch- inson's Archives). We next find that iron-water, prepared by macerating rusty nails, is recommended to be taken immediately after the oil, the taste of the oil and of the eructations being thereby agreeably changed into ' the flavour of oysters ' (Reo. de med. et chi/r. milit.'). Chevrier, Paris : 01. morrh. balsam. — Pix liquid 1 part, bals. tolut. 3 parts, syr. sacchari 4 parts, sp. v. reot. 4 parts. Digest for four hours and then shake with ol. morrh. 1,000 parts. Separate the clear oil. Hager recommends an addition of oil of peppermint 1 part, and 5 parts of chloroform to 600 of cod-liver oil (Pharmaceutische Cen- tralhalle, x. 15). Pavesi — 40 parts of cod-liver oil digested with two of roasted cofiee and one of animal charcoal {6iom. di fa/rm. 1870). Duguesnel. — Flavouring with 1 per cent, of eucalyptus oil (Bull. gen. de th&rap. 1883). Another recipe is: Wood-tar 4 parts, sol. of ammonia 20 parts, oil 1,000 parts. First shaken and then boiled as long as ammonia is given ofi"; after cooling, 8 drops oil of anise are added {Ph. G. xxv. 546). A. Ferguson, jun. — The oil to be combined with the fruit of cacao, or with the usual ingre- dients of cocoa or chocolate. This idea was thought so valuable as to be worth a patent- No. 4495, 1880. R. F. Ferguson. — One part of tomato or walnut ketchup to be added to 4 parts of oil. The same authority also recommends the following mixture: Liebig's extract 8 parts, Ixii PHAEMAOEUTIOAL ANNOTATIONS extract of celery seeds 1 part, vinegar 16, water 32, and cod-liver oil 80 parts (Amer. Jown. of Pharm., through The Chemist and Druggist, xxxiii. p. 167). Dr. Fonssagrives. — Ood-liver oil 96 gnn., iodoform 20 centigr., and essence of anise 4 drops. ' The taste and smell of the oil are completely masked,' but, 'should it still be repugnant,' we are recommended to take it with 'a small dosis' (? a grain) ' of salt' {Gaz. des hdpit. 1882). Lastly we may mention the combination of cod-liver oil with saccharine: Saccharine 40 centigr., acetic ether 2 grm., cod-liver oil 100 grm., peppermint or cinnamon oil q.s. Dis- solve the saccharine in the ether and add cod- liver oil, little by little, with frequent agitations; finally add peppermint or cinnamon oil (Wiener Minische Rwndschau). Liniments, Jellies, and Emulsions The next development in the art of masking and disguising cod-liver oil was by incorporating it into liniments, jellies, and emulsions. So far as the writer is aware, the liniments were originally German inventions, jellies French, and emulsions American. Liniments. — ^These are made very much in the same way as linimentum calcis. The first that we have found is oleum morrhusB calcinatum, a Viennese preparation dating from 1868, and consisting of equal parts of oil and lime-water. Even as late as 1889 we find Lefaki recommending this liniment with the addition of some palatable syrup. He confidently asserts that the oil in this form does not stick to the palate and leaves no after-taste (Thera/p. Gazette, 1889, p. 488). Jelties. — A jelly, crSm^ d'huile de foie de m/yrue, appeared some twenty-five years ago in Paris. It was prepared from cod-liver oil 460 parts, sugar 160 parts, white of eggs 200 parts, heated to 40°, mixed with 100 parts of a solution (1-40) of gelose (Chinese gelatin, parabin) and 50 parts of aqua amygd. amar (Leroy, Ph. 0. ix. 319). Up to the present there seems to be a craving for jellies ; for as late as 1890 we find a formula : — Gelatin 2 oz. Water 15 „ SoaJ: over night. Add Syrup . 10 oz. Melt over a water-bath, then pour into a mortar con- taining Cod-liver oil 25 oz. Chloroform 20 m Oil of cinnamon . . . . . 5 „ „ bitter almonds . . . . 3 „ Stir until the fluids assume a uniform appearance, then pour into bottles, before cooling (Gh. & D. xxxvi. p. 26). Emulsions. — Nearly everything capable of emulsifying cod-liver oil has been called into requisition, such as gums, eggs, dextrin, malt, moss, quiUaia, etc. The following are specimens of the difierent sorts: — Simple Emulsion with Gum Acacia Cod-liver oil Powdered gum acacia .... Saccharine (made into a 10-per-cent. solution by adding 8 grains of sodium bicarbonate to 20 grains of saccharine and water q.s.) . Oil of cassia „ bitter almonds Water to make i oz. 1 „ 2gr. 4 rn, 8 oz. Mix the oils with the gum in a dry mortar, add the saccharine solution and 2 oz. of water, stir till the emulr sion is formed, and finally add water to make 8 oz. (Gerrard's formula, Oh. d D, xxxi. p. 646). EMtrtsioN WITH Gdm Acacia and Hipophosphites These are chiefly represented by 'proprietary articles.' The following are different analyses of the same compound : — Cod-liver oil Glycerin Hypophosphite of calcium It „ sodium Water .... Gum acacia and flavouring (Accord, to ' New Idea.') 35'5 parts 18-5 „ 1-0 „ 10 „ 420 „ q.s. PHAEMAOBUTIOAL ANNOTATIONS Ixiii Cod-liver oil 24-25 parts Glycerin 20-21 „ Hypophosphites of calcium and sodium 2 „ Water 44 „ Gum acacia 11-12 „ (Average of four analyses by Dr. Hermann Hager.) Emulsion with Gum Acaoia, Htpophobphitbs, Ibon, AND ManOANBSE Cod-liver oil 16 oz. Sugar .... 4 „ Gum acacia . 2 „ Hypophosphite of calcium 200 gr. „ „ sodium 120 „ Ferrous sulphate . 76 „ Majiganous sulphate . 38 „ Oil of bitter almonds . eta „ cloves 2 „ Essence of vanilla 5 „ Water .... ct.s. Dissolve the sulphates in 2 oz. of hot water and 15 drops of hypophosphorous acid ; add 80 grains of hypo- phosphite of calcium ; stir well and bring to the boU, then filter and wash the filter and contents with hot water to 3 oz. ; in the filtrate dissolve the remainder of the hypo- phosphites. Place the gum and sugar in a mortar, mix the oil with them thoroughly, and add 8 oz. of water, triturating thoroughly. Then gradually add the hypo- phosphite solution, the flavour, and sufficient water to make 30 fl. oz. {Ch. & D. xxix. p. 563.) God-lactone is an emulsion to which is added lacto - phosphate of lime (Gh. & B. xliii. p. 598). Emulsion with Tbagacanth and Hypophosphites Cod-liver oil . Powdered tragaoanth Tincture of benzoin (1 Spirit of chloroform Glycerin Oil of bitter almonds „ lemon Distilled water Calcium hypophosphite Sodium „ Potassium „ . 40 oz. . 200 gr. ■10 rectd. spirit) 5 oz. 10 drms. 2 „ 2 „ 40 vt 40 „ 80 oz. 40 gr. 40 „ 80 „ Place the oil in a Winchester quart and pour into it the powdered tragacanth, tincture of benzoin, and spirit of chloroform mixed ; agitate briskly for one minute, then add, all at once, a pint of distilled water and agitate as before ; lastly add the oils, glycerin, and remaining water in which the hypophosphites may be dissolved, or added to the emulsion afterwards as required (Baily's formula in ' Physicians' Pharmacopoeia,' Ch. S D. xxx. pp. 305, 341). Emulsions with Gum Acacia and Tbagacanth Powder of tragacanth . . . . 15 gr. „ „ gum acacia . Syrup .... rubbed into a paste, add Water .... 15 „ J oz. lioz. Bub into a good mucilage, and add by a thin stream Cod-liver oil 2j oz. Essence of lemon . . . . 12 rn, Essent. oil of almonds ■ . . 2 „ These being well incorporated, add gradually Distilled water 2f oz. And lastly add cautiously Eeetified spirit f oz. The excellency of the emulsion is in pro- portion to the diligence of the operator in using his pestle and mortar (Squi/re's Oow/panion, 1894). Powdered tragacanth . . 800 gr „ gum acacia . .1,200 „ „ arrowroot . 800 „ Eub well in a mortar with Cod-liver oU . . 80 fl. till consistency of cream ; transfer to a B-gallon bottle and add, all at once, a mixture of Glycerin 10 oz. Water 70 „ Shake well for 10 minutes and then pour in Spirit of chloroform . . . . 2g oz. Oil of lemon 160 ra Shake again well {Ch. & D. xxxiii. p. 388). Combination of Liniment and Tbagacanth Emulsion Powdered tragacanth .... 2 drms. Eub up with Glycerin 2 oz. and add Boiling water 8-10 oz. Make into a firm jelly, and when cold add gradually Cod-liver oil 40 oz. previously mixed with Lime-water 15 oz. Ixiv Finally add Oil of almonds dissolved in Bectified spirit PHARMAOEUTIOAL ANNOTATIONS 20 drops 2oz. An addition of 2 grains of chloride of sodium to each ounce of emulsion will improve the emulsion and make it more palatable {Ch. S D. Diary, 1881). Emulsion with Panoebatin Many preparations have been made with the avowed object of increasing the efficiency of cod-liver oil by the addition of pancreatin. One of the first of these, an American prepara- tion, was dignified by the name Hydroleine. So far as the writer knows, this is now extinct — at least on this side of the Atlantic. It was, according to the label accompanying it — 0-3 part 0-2 „ 30-0 „ 4-0 „ 0-5 „ Soda Boric acid Water . Pancreatin Hyocholio acid Cod-liver oil . 65-0 The so-called hyocholic acid is probably nothing more nor less than bile. The name is a purely fancy one of American invention, and quite unknown to scientific chemistry ; but the substance, whatever its composition may be, makes itself painfully en Evidence to the olfactory and" gustatory nerves when the pre- paration containing it has become sufficiently matured. Hydrated codrliver oil is an English edition of a similar composition. It also was known as hydroleine, a proprietary medicine. ' The delicacy of adjustment ' of its essential points, ' both in the chemical reactions and in the manipulation necessary to produce the required combination,' etc., ' is so great as to render it difficult of manufacture, even under the direc- tion of so able a chemist as,' etc. — so says a booklet written in praise of hydrated oil by a gentleman with ' M.D.' after his name. The brilliancy of this idea seems to be fas- cinating, for we find it revived in Germany in 1887. It is improved, of course, by the scientific acquirements of intervening years, and therefore taurocholates are substituted for bile, and olive oil for cod-liver oil, for which reason it will appear further on, under the heading of 'substitutes' and the name of Pinguin. Emulsion with Eqos Yolks of eggs 2 Powdered sugar . . . . 4oz. Oil of bitter almonds .... 2 drops Orange-flower water . . . . 2 oz. Mix and add an equal bulk of cod-liver oil (Ch. £ D. XXX. p. 83). Emulsion with Eggs, Eum, and Phosphobio Acid (A Washington Eobmula) Dilute phosphoric acid (U.S.) Yolks of eggs Cod-liver oil . Glycerin Oil of bitter almonds New England rum Orange-flower water to make (Gh. & D. xxxii. p. 281.) Apparently the tragacanth emulsions, in spite of the praise lavished upon them on their first appearance, have proved no more satis- factory than the egg emulsions, because we find some years later attempts being made to im- prove upon them hy comMning the two. Emulsion with Tragacanth akd Egos Powdered tragacanth . . . . 24 gr. Yolks of eggs 2 Hypophosphite of calcium . . .48 gr. „ „ sodium . . . 48 „ Glycerin 1 oz. Eub together in a mortar. Add in their order, and in the proper manner for making an emulsion Orange-flower water Cod-liver oil . 1* oz. 3 8 oz. H »» 20 m. 8 oz. 2 pints Oil of bitter almonds „ cinnajnon . Chloroform . Saccharine . dissolved in Jamaica rum .... Make up with orange-flower water to 2 oz. 24 „ 15 m 25 „ 10 drops 5gr. 5 drms. 36 fl. oz. (O/i. & B. Biwry, 1890.) PHARMACEUTICAL ANNOTATIONS Ixv Another formula in which there is 50 per cent, of cod-liver oil, as against 66-6 per cent. in the preceding one : — Cod-liver oil. Yolks of eggs Powdered tragacanth . Elixir of saccharine . Simple tincture of benzoin Spirit of chloroform . Essential oil of bitter almonds Distilled water to make Measure 5 fl. oz. of water, place the tragacanth in a dry mortar, and triturate with a little of the cod-liver oil ; then add the yolk of eggs and stir briskly, adding water as the mixture thickens. When of a suitable consistency add the remainder of the oil and water alternately with constant stirring, avoiding frothing. Transfer to a pint bottle, add the elixir of saccharine tincture of benzoin, spirit of chloro- form, and oil of almonds, previously mixed ; shake well and add distilled water, if necessary, to make 16 fl. oz. (unofficial formulary, British Pharm. Conference). 8 oz. 2 16 gr. Ifl. drm 1 „ 4 „ 8ni 16 oz. Emulsions with Malt Extract The mixture of malt extract and oil is probably, also, an American idea. We give below the original formula and a couple of the so-called improvements upon it. Equal parts are mixed by adding the oil to the warm extract in small portions, at first of 5 per cent., later 10 per cent. The mixture becomes at last so thick that water has to be added. Emulsions with Malt Exteact and Panokeatin Cod-Uver oil 14-60 parts Powdered gum acacia .... 8-00 „ Glycerin 5-00 „ Peptic substances . . . . 0-10 „ Pancreatin 3-4'00 „ Malt extract 37-50 „ Syrup 18-50 „ Water 12-12-50 „ Salicylio acid 0-14 „ (Average of four analyses by Dr. H. Hager.) This is one of the so-called solutions of cod-liver oU, their description as ' solutions ' being an ingenious invention of our American cousins. The slightest acquaintance with the properties of its several constituents will suflBce to convince anyone that there can be no possibility of a solution. It is no doubt useful for trade purposes to describe it thus, relying for proof upon an optical illusion. Under the microscope the appearance of the preparation is uniform, no oil globules being visible ; but this is caused by the fact that the extract and the oil have nearly the same index of refraction. Just as, for the same reason, many bacteria long escaped detection by the microscope, but became visible when coloured, so the oil globules in the so-called solution become visible when coloured with wolframic or osmic acid, or simply by the employment of a small diaphragm. It will then be seen that the ' solution ' is, in reality, an emulsion, and with oil globules which are certainly not smaller than those of any ordinary emul- sions. The presence of salicylic acid is probably necessary for the preservation of the malt extract, but it must be therapeutically objection- able in many cases. Judging from Dr. Hager's analyses, the malt extract employed in the particular brand he examined is mixed with syrup. The emulsion contains cod-liver oil to the extent of only 15 per cent., according to the analysis. Another of the improvements derived from malt extract and pancreatin with hypo- phosphites is — Panokbatio Emulsion Cod-liver oil , . . 8 fl. oz. Extract of malt . . 8 „ Pancreatin . 256 gr. Oil of gaultheria . 32 m „ cmnamon . . 16 „ Alcohol .... 4 fl. drms Syrup of hypophosphites (U.S.), ( make 32 fl. oz. Beat the extract of malt in a mortar until it can be drawn into strings, add the pancreatin, and mix thoroughly. Then add the oil, in small quantities at a time, and beat until a smooth mass results. Add the alcohol and essen- tial oils, then gradually incorporate the syrup by tritura- tion. Here there is 25 per cent, of oil {Amer. Drug. 1886, No. 11). d Ixvi PHARMACEUTICAL ANNOTATIONS Emulsions having once become the order of the day, everything that could make them has been introduced, and has had more or less of a run, as is the way with novelties. The following are some modem specimens : — Emulsion wiih Dextbin Cod-liver oil . . . Mucilage of dextrin (1 in 3) Syrup of Toln . Flavouring . Water to ... . 8 fl. oz. 5 „ 2 „ q.s. 16 fl. oz Add oil in small portions to the mucilage in a bottle, agitating each time ; then flavouring, syrup of Tolu, and lastly water (Ch. £ D. xzxiii. p. 768). Emulsiok with Caebageen Decoction of carrageen moss . . 100 parts Cod-liver oil 120 „ Sugar 20 „ Aromatic oils ad Ub. made into an emulsion by beating, not by triturating (i' Union pharm. 1881, x.). Carrageen moss 1 drm. Make a decoction in a water-bath to . 5 fl. oz. and add Glycerin 2 fl. oz. Alcohol 1 ,1 Oil of bitter almonds .... 5 drops „ gaultheria . . . . 3 „ when cold add Cod-liver oil 8 fl. oz. in three portions, shaking vigorously after each addition {Pharm. Becord ; Ch. d D. xxx. p. 581). Emulsion WITH QUILLAIA Cod-liver oil 8fl. OZ Tincture of quillaia 1 „ Syrup of Tolu . 2 „ Flavouring . q.s. Water to . • « 16 oz. Put the tincture in a suitable bottle, add the oil, two ounces at a time, shaking thoroughly to ensure complete emulsiflcation ; then add the rest and shake again thoroughly [National Formulary ; Ch. S D. xxxiii. p. 768). Emulsion with Condensed Milk Cod-liver oil . . . . 8 parts Condensed milk Glycerin or syrup Water Milk rubbed in a mortar, oil added gradually; lastly glycerin and water (Br. (& Col. D. xix. p. 162). Pbepaeations with Cod-livek Oil We have so far described the methods used to cover or disguise the disagreeable flavour of the oil, and in some cases the simultaneous incorporation of other compounds supposed to increase the therapeutical effect of the oil. We may now turn to a" class in which little regard has been paid to the gustatory organs, the sole object being to combine with the oil such sub- stances as are likely to endow it with supple- mentary or increased efficiency. The value of these additions is always great — according to their inventors — ^but the preparations them- selves are, as a rule, far from nice, and the poor patient is left to overcome his aversion to swal- lowing them as best he can. In some of the preparations the utmost ingenuity has been brought into play in order to combine cod-liver oil, a body with a most delicate and sensitive constitution, with some of her bitterest enemies, in a chemical sense. If emulsionists condemned the oil to life- long servitude, the improvers upon them may certainly be said to have issued its death- warrant. Iron is the chief factor that has secured the attention of workers in this field ; and no pains have been spared to obtain a properly constituted oleum morrhuce /erratum. A method for preparing an oil with a constant percentage of iron seems to have been successfully devised. But what an oil! In spite of assurances to the contrary — always emanating from the inventors of these preparations — we doubt if many persons could be persuaded to take them, except, of course, little children, with whom persuasions of a certain kind are generally followed by satisfactory results. We shall now give a short survey of the efforts made in order to obtain a reliable oleum morrhuce /erratum. The first attempt was made as far back as 1861, but it was a comparatively tame one. Jeannel gave the following sugges- tion : 250 parts of oil are mixed with 14 parts of sodium carbonate, 14 parts of ferrous sul- PHARMACEUTICAL ANNOTATIONS Ixvii phate, dissolved in 250 parts of water, shaking occasionally for a week, and then filtering (Itep. de pharm.'). An improvement upon this, is to prepare first ferrous carbonate from ferrous sulphate by sodium carbonate, and then dissolve the pre- cipitate in the oil heated on a water-bath (Phwrm. Oenimlhalle, ii. 369). Three years later the same journal proposes to dissolve ferrous stearate in the oil, but admits that it does not dissolve perfectly. Two years afterwards C. Waeber, in Phwrm. Zeitsch. fiir Uuslamd, 1866, recommended ferrous oleate in preference to stearate because it dis- solves in all proportions. In 1866 Ricker {N. Jahrb. d. Pha/rm.') re- commended the preparation of an iron soap from the fatty acids of cod-liver oil by saponification with caustic soda, dissolving the soap in water and precipitating with ferrous sulphate. The precipitated iron soap is then dissolved in the oil. The percentage of iron in all these pre- parations is variable, and in order to obtain an oil with constant percentage Stromeyer {Arch. d. Ph. xv.) devised the following me- thod : 20 grms. of Castile soap are dissolved in 800 grms. of water ; to the solution are added 7*5 grms. of a solution of ferric chloride (15 per cent.) ; 16 grms. of the iron soap thus formed are mixed with 84 grms. of cod-liver oil, the whole being gently heated. The preparation contains 1 per cent, of iron. Such a discovery proved quite a stimulus to emulous pharmacists, and from Germany, France, and Holland there came in quick succession reports of still greater discoveries. Thus Schwartz (Ph. Zeitg. liii.) recommends iron benzoate in making ol. morrh. ferr. He dis- solves 60 grms. toluyl-benzoic acid in 300 grms. water, adding 102 grms. liquor ammonise (10 per cent.); a mixture of 100 grms. Tr. ferri perchloridi and 300 grms. water is added, and the precipitate washed and dried: 20 grms. of this iron benzoate is triturated with 5 grms. toluyl-benzoic acid and some cod-liver oil. mixed with 1 kilo, more oil, and heated on a water-bath for an hour. It contains 2 per cent, ferric benzoate, or 0'3 per cent, metallic iron. Godin, Paris, had a similar happy idea — dissolved 1 per cent, ferric benzoate in the oil. The preparation must, however, not be exposed to light, otherwise 'it assumes a rather un- pleasant taste.' Van der Burg (Ph. Ztg. 1881) prepares an iron-oil in this way : — Pour 3'5 parts of caustic soda solution into 100 parts of oil, heating on a water-bath, add 2 parts of ferrous sulphate, passing a current of air through the mass and keeping the temperature up to 90°. A compound is thus, obtained which is quite clear, of a dark garnet-red colour, contains 0'25 per cent, iron, and 'has an unpleasant taste and smell.' It is therefore recommended to dilute it with — cod-liver oil. Van Valkenburg's method of preparing an oil with iodide of iron : — Iodine, 1'25 parts, and cod-liver oil, 98*50 parts, are shaken up for some days until the iodine is dissolved, then 2*50 parts of iron are added, and the whole shaken occasionally until there is no reaction of free iodine. Dietrich (Neues ph. ManuaF) gives, as late as 1886, two prescriptions for preparing oleum morrh. ferr. , proving that this hapless preparation still haunts the pharmaceutical brain. One is identical with Godin's formula, the other is similar to Stromeyer's, both referred to above. Oleum MORBHUiE ozonisatum: a French remedy prepared by leading ozone through the oil ! ! Oledm morrhu^ chloralisatum : cod-liver oil 190 parts and chloral hydrate 10 parts. Oleum morrhu^ cum creasoto: cod-liver oil 4 fl. oz., creasote (beechwood) 100 minims, and saccharine 2 grains. Oleum MORRHUiE cum oleo eucalypti: 5 minims of eucalyptus oil to each drachm of cod-liver oil, made into an emulsion. Oleum morrhu^ etherisatum, the only sensible preparation as yet suggested, was introduced by Dr. Foster, of Birmingham, and ■ d2 Ixviii PHAEMAOBUTIOAL ANNOTATIONS founded upon Claude Bernard's investigations on the mode of stimulating the secretion of the pancreas (vide British Medical Journal, Nov. 21 and 28, 1868). Dr. Poster recommended three degrees of strength to suit individual cases : 1, 3, or 5 minims of ether to 1 drachm of oil. Oleum moerhu^ phosphoratum : phos- phorus 0-01 part dissolved in 100 parts of oil. Oleum MORRHUiE phosphorale is a solution of 0-6 per cent, phosphorus in oil. Oleum morrhu^ saponifioatum : slaked lime 40 parts, water and oil each 100 parts, evaporated to the proper consistency for making pills. Pitjecor is a mixture of cod-liver oil and catramin (B. Med. Ztg. 1890, p. 147). Substitutes Substitutes for cod-liver oil have been brought more to the front by reason of the preparations just described. These have chiefly succeeded in rendering the oil perfectly horrible, while the substitutes are, at least, more palatable. They have, however, never met with extended sympathy amongst medical men, for many reasons. Their scientific vindication has been small to a degree, frequently incomprehensible, supported by mere postulates, without any con- firmatory facts. A great many have been nothing more than pecuniary speculations, whose flicker has been fanned into flame by flour- ishing advertisements, and belong to the prolific class of patent medicines and proprietary articles. With the latter we shall not trouble the reader, but it may be interesting to recall some others which have attained a certain measure of favour. The first substitute that we have come across is cream, which is recommended as an excellent substitute for cod-liver oil (Bull. tMra/p. 1863). Next PORK-FAT {Br. Med. J. 1879), which is followed by a mixture of spermaceti 1 part and sugar 3 parts (Monde pharm.). Then GLYCERIN, simple, is declared as good as the oil (Ph. G. v.), but has been superseded by Glycerinum tonicum, which is composed of glycerin 300 grms., tinct. iodi 30 drops, and iodide of potassium O'B grm. Several other oils have served as substitutes. Shark-liver oil from Squalus uyatus is by Italiain practitioners considered quite equal to ordinary cod-liver oil, probably their consti- tutions are somewhat similar. Bulachon oil, the fluid fat of Thaleichthys padficus, the candle- fish found in the Pacific : this is, however, not liver oil, and has not its physical properties, being much more viscous. DuGONG OIL, which is said to some extent to substitute cod-liver oil in Australia, is the fat from the halicore or dugong (sea-cow), an herbivorous cetaceous animal belonging to the Manatidoe, and found in the Indian Ocean : this, again, is not a liver oil. Japanese cod-liver oil is said to be derived from Gadus Brandti, a Japanese species of the cod. Alligator oil, crocodile oil, and turtle- egg oil have also been used instead of cod-liver oil. A milk decoction of the leaves of the great MULLEIN (Verbascum thofsum) is reputed to have the weight-increasing properties of cod-liver oil, and is said to be much used in Ireland. ' It is superior in point of view of comfort to the patient ' (Br. Pharm. Congress, 1883 ; vide Gh. & B. XXV. p. 500). Creasote and guaiacol have been recom- mended as substitutes ; but as they therapeuti- cally belong to a class of materia medica widely different from cod-liver oil, it is difficult to see how the one can be substituted for the other. Creasote and guaiacol are supposed to destroy the tubercle hacillus, and consequently to cure the disease : the oil has no efiect upon the bacillus, but provides materials for rebuilding the cells destroyed in the combat between them and the bacilli. Creasote and guaiacol may therefore be valuable adjuncts to the oil, but they cannot be substitutes for it. There are several other preparations of the dietetic category. In these meat in one form or another forms the principal constituent, as PHAEMAOEUTIOAL ANNOTATIONS Ixix meat-powder, meat-cliooolate, etc. Besides these there is an imposing array of proprietary- articles, the compositions of which are ' trade secrets,' and probably in most cases it would be inexpedient to declare the various ingre- dients, upon the principle that ' where ignorance is bliss, 'tis folly to be wise.' Active Principles Another class of substitutes enjoys a quasi- scientific origin resting upon the basis of the, so- called ' active principle ' of the oil. The oldest of these active principles, iodine, was detected as one of the oil's constituents so far back as 1836 by Hopfer de I'Orme, and the percentage was variously stated to be from 0-0293 to 0-324 (100 to 1,000 times higher than the percentage, as since ascertained by more accurate modem methods). A most varied selection of iodine preparations as substitutes for the oil followed upon this discovery, the last example of which has already been mentioned as glycerinum tonicum, born 1871, died shortly after from consumption — or perhaps rather from too small consumption — secundum legem talionis. When the iodine active principle was ex- ploded another, trimethylamine, took its place, and as a result herring-brine, from being a rather neglected commodity, became for a short time the desideratum of the day. After a quick succession of other active principles, too evanescent to be worthy of even an obituary notice, the turn came for the free fatty acids. No theory and no fact then sup- ported the idea that these acids were the active principle in the oil ; on the contrary, all obser- vations tended to demonstrate that their presence was immaterial to its therapeutical value. Still, the belief entered some active mind (Therwp. Mohatsh. ii. 2) that they were the essential constituents, and that they might be fitly represented by oleic acid, now proved conclusively not to be present in cod-liver oil. The new substitute was compounded from olive oil, to which was added 6 per cent of oleic acid and given the name Lipanin. It had, like its brethren, a short life, though its great discovery was so enthusiastically received that one of the authorities recommended it as being, in addition to its therapeutic virtues, an excellent substitute for — salad Lipanin was improved upon by a product, substituting lanolin for oleic acid, and by another replacing olive oil by cacao-butter. The former was objected to by therapists (Therwp. Monatsh. 1888, p. 3) because lanolin is not absorbable by the intestines. The latter, euphonised invigorating chocolate (Krafit-Choco- lade), is compounded, it seems, by none other than the discoverer of lipanin : as it is still in the youthful stage we have no desire to cast its horoscope. According to Marpmann (Ph. 0. xxix. p. 406) pancreatic juice and cod-liver oil both contain an identical compound which easily emulsifies oil ; it has, however, not been isolated, and is therefore merely hypothetical. But upon the hypothesis follows a theory, and upon this, of course a new substitute is compounded. The theory is as follows : cod-liver oil is thera- peutically only a fat in the place of which any other fat wUl do equally well if mixed with the active principle, i.e., the emulsifying agent referred to. This is found in pancreatic juice, and therefore olive oil digested with pancreatic juice is ' highly recommended as a substitute ' for cod-liver oil. Of course this was soon afterwards improved upon, by the addition of phosphate of calcium, alantol, alantic acid, and taurocholates, sug- gested by the American preparation hydroleine, previously referred to. The new improved edition of digested olive oil has made its d6but as PiNGUIN. There are still two or three 'active principles' which have had, or still have, to serve as substitutes for cod-liver oil. Despinoy and Garreau (according to Zeitsch. d. allg. osierr. Apoth. Vereins, Ph. G. Ixx PHARMAOEUTIOAL ANNOTATIONS V. 53) have found that the active principle of the oil is not in the oil at all, not even in the livers, but in the water squeezed out when the livers are macerated. This fluid contains a great percentage of ichthyoglycin (whatever that may be), chlorine, iodine, phosphoric acid, and propylamine. The product is made into pills which 'produce want of appetite and diarrhoea.' Nevertheless eight of them are equal to 360 grains of the oil on account of their favourable action on the nutrition ! ! Meynet (according to Neues Jahrbuch f. Phwrmacie, Ph. G, vi. 202) made drag6es from the watery fluid of the livers, and a com- mittee appointed by the authorities, at his instigation, to report upon the remedy stated that ' an analysis had disclosed the fact that the efficacy of 20 grammes of the extract was equal to that of 6 litres of cod-liver oil ' ! Chapoteaut (American Journ. Ph. 1886) has isolated a body which he calls morrhuol, and which, he says, represents the active principle of cod-liver oil. It is prepared from the oil by first treating it at a low temperature with an aqueous solution of sodium carbonate and then shaking it with alcohol (90 per cent.). The alcoholic solution, separated and evaporated, leaves a residue which is morrhuol, a strongly smelling substance having a sharp and bitter taste : it partly solidifies at ordinary tempera- tures, and is said to contain iodine, bromine, and phosphorus. The discoverer computes 0*02 grm, to be equal to 6 grms. of oil. Morrhuol is evidently identical with the ptomaines found in light-beown cod-liver oil by Gautier and Mourgues (hs alcalmdes de I'huile de foie de morue), viz., asseline, morrhuine dihydrolutidine, etc., and which were collectively termed paMg'fwZMirie byBouillot (Gompt rend. cxvi. 439). They are poisonous substances, probably analogous to if not identical with those found in putrid meat, poisonous cheese, etc. ; and those should with the same right be considered the ' active principle ' of cheese and meat, and used for the benefit of 'sufiering humanity.' Wine of cod-liver oil, so called, appears to be identical with a solution of morrhuol. The real active principle of cod-liver oil will be discussed later in connection with Heyerdahl's researches and discoveries. We shall see how hopeless is this search after a substitute for cod-liver oil, for the simple reason that the main constituents of the oil are absolutely unique, and that its active principle is the oil itself. Ixxi CHRONOLOGICAL SYNOPSIS OF CHEMICAL RESEARCHES ON COD-LIVER OIL CONIBIBDTED BT P. M. HETEEDAHL 1822.— Wurzer (Eufel. Journ. Dec. 1822, p. 31). The first chemical examination of cod- liver oil was made by Wurzer in 1822. Light brown oil was shaken up with water, and the aqueous yellow extract, left on evaporation, was a viscous, yellowish substance, acid in reaction, smelling of herring, disgustingly bitter to the taste, deliquescent, and soluble in water and alcohol. 1828. — Spaarmann (Geig. Mag. June 1828, p. 302) examined Kght brown oil. With water he extracted 4'5 per cent, of a fishy-smelling substance, of an acid reaction, soluble in alcohol and precipitated by acetate of lead or infusion of galls. The oil was next dissolved in boiling alcohol, and after being cooled it separated into 19 parts stearin (margarin) and 76*5 parts olein. He saponified the oil with caustic potash solution and decomposed the soap with tartaric acid; the separated free fatty acids were then dissolved in boiling alcohol, from which, upon cooling, margaric acid crystal- lised. The mother liquor was distilled, and the acid distillate after being neutralised by baryta water was evaporated and decomposed by phos- phoric acid, when delphinic acid separated ; not free, however, from colouring impurities, and with the smell of herring brine. The delphinic acid was a brownish yellow oil, sp. gr. 0'941. One hundred parts of cod-liver oil yielded in this way — 17 parts of margaric acid 74'5 „ oleic acid 5*5 „ delphinic acid 3-0 „ colouring and smelling matter ' 1830.: — Harder (Brandes Archiv, xxxii. 90 ; Pharm. Gentralhl. 1830, p. 17; and Hufel. Journ. May 1837, p. 115) examined brown cmd pale oils, and found the constituents of the oils and their percentage to be : — Pale oa Brown oil Green soft resin . . 0-052 0-065 Brown hard resin . . 0013 0-078 Animal glue (gelatine) . 0-156 0-468 Oleic acid . 55-917 47-500 Margaric acid . 10-312 4-000 Glycerin . 8-416 9-000 Colouring matter . . 5-750 12-500 Chloride of calcium . 0-052 0-105 Chloride of sodium . 0-059 0-094 Sulphate of potassium . 0-018 0-031 He found that pale oil exposed to a low temperature deposited a solid fat, consisting of oleic acid, margaric acid, and glycerin, but brown oil did not ; further, that the latter had a greater refractive index and a more acid reaction than the former. The pale oil viewed by transmitted light appeared yellow, but, by reflected light, green. Both were soluble in ether in all proportions. One hundred parts of alcohol, sp. gr. 0-825, dissolved at 77°-5 nine parts of pale oil and one hundred parts of brown oil. Water shaken with either oil acquired an acid reaction and a disgusting smell of train-oil. Both oils were saponifiable with ammonia; formed milky liquids with barium hydrate ; were not affected by tincture of galls, nitrate of silver, nitrate of mercury, stannous chloride, or potassium ferro-cyanide. With large quan- tities of solution of subacetate of lead they formed a sort of liniment. By mixing with Ixxii CHRONOLOGICAL SYNOPSIS nitric acid no heat was evolved, but the acid altered the odour and deepened the colour. Sulphuric acid produced, with evolution of heat and formation of sulphur dioxide, a red colour turning into black, and made the oil more viscous. Solution of chlorine had no particular effect upon either of the oils. 1836. — Hopfer de I'Orme (Hufel. Joum. April 1836, p. 115) was the first to recognise the presence of iodine in light brown oil. 1838. — ^Wachenroder (Arch. d. Ph. xxiv. 145; Geniralbl. 1841, p. 11) saponified the oil by boiling it for a considerable time with pure caustic potash in excess, evaporated the soap-solu- tion to dryness, ignited the soap in a platinum crucible, adding a little ammonium carbonate towards the close, and finally extracted the soluble portion of the ash with water or alcohol. In the latter case, after evaporation of the alcohol, a fairly pure potassium iodide remained, which was dissolved in water and precipitated with nitrate of silver. The pre- cipitate was treated with dilute nitric acid and subsequently with ammonia to remove the silver chloride, bromide, and carbonate, and it was then washed and dried. Brown oil yielded 0'324 per cent, of iodine in one case, and iu another 0*162 per cent. 1839. — Herberger (Ann. d. Oh. xxxi. 94; Jahrb.f.pr. Ph. 1839, p. 178; Gentralhl. 1839, p. 853) dissolved the salt, obtained by ignition, in water, precipitated the iodine with blue and green vitriol as cuprous iodide, filtered, evapo- rated, and distilled the residue with manganese peroxide and sulphuric acid, agitated the distillate with ether, and, after evaporation of the latter, determined the bromine as potassium bromide. He obtained the following results : — Iodine Bromine Per cent. Per cent. In pale oil . 0-0293-0-0903 0-0170 „ light brown oil . 00375-0-1723 0-0294 „ brown oil . 00318-0-0412 00101 Herberger assumed that bromine was present in the form of magnesium bromide because magnesia was found in all samples containing bromine, but not in those destitute of bromine. 1840.— Stein (Jou/m. f. j)r. Oh. xxi. 308) showed that the percentage of iodine could not be determined by simple extraction with alcohol, ether, or water, nor could it be done reliably by direct carbonisation of. the oil and treatment of the carbon with solvents, but only by saponification of the oil with caustic potash or soda and ignition of the soap. Qualitatively the presence of iodine was best demonstrated by heating the aqueous or alcoholic extract of the ignited soap (evaporated to dryness) with concentrated sulphuric acid, when the fumes arising would react on starch. 1843. — De Jongh (BisquisiUo Gompa/rativa Ghemico-medica de Trihus Olei Jecoris Aselli Speciebus) made an extensive examination of pale, light brown, and brown oil, of which the following is an extract. Physical Properties. — The brown oil, oleum jecoris aselli fuscmn, is of a dark-brown colour, greenish in refracted light, and transparent in thin layers ; its smell is peculiar and unpleasant ; its taste bitter, empyreumatic and caustic ; reaction on litmus paper slightly acid ; sp. gr. at 171° 0-924. Cold alcohol dissolves from 6"9 to 6'5 per cent., boiling alcohol 6-6 to 6"9 per cent., and it is soluble in all proportions in ether. The light-brown oil, olevm jecoris aselli sub- fuscum, is in colour like Malaga wine; smell peculiar, not unpleasant, but stronger, however, than that of pale oil ; taste fishy, bitter, and burning in the throat. Slightly acid reaction ; sp. gr. at 17A° 0-924. Cold alcohol dissolves from 2-8 to 3-2 per cent., hot alcohol from 6-5 to 6-8 per cent. Ether dissolves it in all proportions. The pale oil, oleum jecoris aselli flavum, has a golden yellow colour ; a smell peculiar, but not unpleasant ; taste fishy, not bitter ; reaction slightly acid; sp. gr. at 17^° 0-923. Cold alcohol dissolves from 2*5 to 2'7 per cent. ; hot alcohol from 3-5 to 4-5 per cent., and it is dis- sol\»ed by ether in all proportions. CHRONOLOGICAL SYNOPSIS Ixxiii Organic Constituents. — Bilious Matters. — The three oils were agitated with cold water, producing an emulsion from which the oil slowly separated. The brown oil caused the water to become discoloured and empyreumatic, while neither of the other oils discoloured it : in all three cases the water assumed a slightly acid reaction. The oils after the agitation were clearer, less strong in smell, and less acid in reaction. Boiling the oil with water gave the same results. By evaporation of the aqueous extract a reddish-brown substance was obtained, which became softer on being heated, and was scarcely soluble in water, more so in ether, and entirely soluble in alcohol. Alkaline fluids dissolved this substance and acids precipitated it again in the form of a reddish-brown flaky deposit. The extracts had a peculiar smell and a bitter taste. The amounts obtained from each of the three oils were as follows : — Pale oil . Light brown oil Brown oil With cold water With hot water Per cent. Per cent. . 0-607 0513 . 0-890 0-849 . 1-288 1-256 Subsequent treatment by ether, alcohol, and spirits gave like results with all of these extracts. By ether there was obtained a reddish- brown, transparent, viscous extract which melted when heated, stained paper, and smelt and tasted like bile. After a time it fornied small crystals. The extract was very sparingly soluble in water, but easily dissolved in alcohol or ether. A solution of ammonium carbonate added to a solution of the extract in ether pro- duced two layers, the upper one being thick and turbid, and on evaporation separating drops of olein, some crystals of margarin, and a brownish substance which had a bitter taste, and proved identical with the substance obtained by evaporation of the lower or ethereal layer, which on treatment with water separated into a soluble and an insoluble part, and consisted of cmumonium fellinate and cholate. Prom that part of the extract which was insoluble in ether, alcohol dissolved a blackish- brown, odourless, bitter, glittering, hygroscopic mass, not easily soluble in water. It consisted of hilifulvin, biliverddn, and bilifellio acid. Dilute alcohol extracted from the residue a black, glistening substance soluble in alkalis, concentrated sulphuric acid, and hot acetic acid, but insoluble in nitric and hydrochloric acids. Baryta water and lead acetate precipitated brown flakes in the alcoholic solution. No ash was left on incineration. That part of the aqueous extract which remained afber treatment with the above-named three solvents contained an organic substance, the nature of which was not determined, and norga/nic salts, among which were found hydro- chloric, phosphoric, and sulphuric acids, lime, magnesia, and soda, but neither potassium nor iodine. Glycerin. — This was prepared by saponifica- tion with caustic soda. The under-lye was drawn off and neutralised with sulphuric acid, and the sodium sulphate thus formed was separated by evaporation and crystallisation. The glycerin so obtained was found on compari- son to be darker than that obtained from olive oil or from lard. All of them were decolourised by adding basic lead acetate to the aqueous solutions, but they turned brown again on heating. Quantitatively the three oils contained glycerin as follows : — Brown oil contained . Light brown oil contained Pale oil contained 9'711 per cent, glycerin 9-073 10-177 The Fatty Acids. — The separation of the fatty acids was effected by decomposing the soda soap with lead acetate and digesting the lead soap with ether. The insoluble part was found to consist of lead wMrga/rate and the ethereal solution contained lead oleate. The quantitative determination gave the following results: — Margario acid Impure oleic acid Per cent. Per cent. Brown oil contained . . 16-145 69-785 Light brown oil contained . 15-421 71-757 Pale oil contained . . 11-757 74-033 Ixxiv CHRONOLOGICAL SYNOPSIS Gaduin. — The ethereal solution of the lead soap from each of the three oils contained, besides lead oleate, a brown substance in each case identical. This was obtained by the following process. "The lead oleate was decomposed with sulphuric acid and the separated free oleic acid saponified with sodium hydrate. After saponification the lye was almost black, containing the greater part of the brown substance. The soap was removed, the lye filtered and neutralised with sulphuric acid, when brownish-yellow flakes were formed rising to the surface. These were collected, washed with water, and dissolved in spirit ; but after evaporation to dryness the substance was not agaia entirely soluble in spirit. The ultimate analysis, however, of the lead and silver salts — the substance appearing to have the character of an acid — and the analysis of the substance itself proved the soluble as well as the insoluble part to be the same compound, but in two modifications. The formula of this when dried at 110° was found to be CggHjjOjj (Berzelius' equivalents C = 75, H = 6"25, = 100), and when dried at 140° G^^K^fi^; the difference C^HgOj being the elementary com- position of ' anhydrous acetic acid,' which de Jongh considered as foreign to the compound, and as having its origin from the lead acetate used for the formation of the lead soap. He gave the brown substance the name of gaduin, and looked upon it as an hydrated oxide of an unknown hydrocarbon OgHg, its rational formula being 7 (OjHgO) 2 (HjO). Of the two molecules of water, however, only one was replaceable by metallic oxides — according to the theories of 1843. Volatile Acids. — These were prepared by saponification with caustic potash and decom- position of the soap with dilute sulphuric acid. The acid aqueous fluid, together with the wash- water from the fatty acids, was then distilled. The distillate had a peculiar odour. When saturated with baryta water and evaporated to dryness a part of it was soluble in alcohol. another part insoluble. The insoluble part was found to be barium acetate with two molecules of water of crystallisation. The soluble part was banum butyrate. Quantitatively there was found — Butyric acid Acetic acid Per cent. Per cent. Brown oil . . . 0-15875 0-12506 Pale 0-07436 0-04571 The percentage in light brown oil was about the same as in the pale oil. Inorganic Constituents. — Iodine. — De Jongh corroborated Stein's observation that iodine cannot be detected and determinated by in- cineration of the oil or by saponification and subsequent decomposition with acids, but only by the saponification and incineration of the soap. Consequently iodine is not present in the oil either in the free state or as a metallic iodide, but probably as some organic combination. The quantitative estimation was effected by Lassaigne's method, by which a perfectly neu- tral solution of the iodine compound is precipi- tated by a perfectly neutral solution of palladium nitrate. The oil was saponified with caustic potash in an iron crucible, the soap incinerated, and after cooling extracted with absolute alcohol. The extract was evaporated, the residue dis- solved in water, the alkaline solution carefully neutralised with dilute sulphuric acid and pre- cipitated with palladium nitrate, the sediment filtered off, washed, and dried at 100°. Brown oil was found to contain Light brown oil was found to contain Pale oil was found to contain . Iodine Per cent. 0-0295 0-0406 0-0374 Brormne. — The presence of bromine was demonstrated by Balard's method. The oil was saponified with caustic potash, the soap in- cinerated and extracted with alcohol; the alcoholic extract evaporated, the residue dis- solved in water, filtered, and treated with chlorine. This solution was then agitated with ether, which assumed a brownish colour, but was decolourised again on treatment with caustic potash solution. The solution was evaporated to dryness, moistened with sulphuric CHEONOLOGIOAL SYNOPSIS Ixxv acid, and heated in a retort; iodine fumes were evolved and also distinct fumes of bromine which coloured the water first condensed in the receiver brown. All oils gave the same result, but the amount of bromine was too small to be quantitatively determined. Ohlorine. — The incinerated potash soap was extracted with hot water, the aqueous solution concentrated, acidulated with nitric acid, and precipitated with nitrate of silver, the sediment filtered oflF, washed, and dried. In the quanti- tative determination allowance was made for the calculated amount of iodide of silver, the rest being chloride and bromide of silver, the amount of the latter being insignificant. Chlorine, inbl. bromine Per cent. . 0-0840 Brown oil contained Light brown oil contained Pale oil contained . 0-1588 0-1488 Phosphoric and Sulphuric Acids. — The oil was saponified with caustic potash, the soap decom- posed with hydrochloric acid, the fatty acids removed, and the phosphoric acid precipitated with ferric nitrate and ammonia in excess. Sulphuric acid was precipitated from the solu- tion with barium nitrate. Phosphoric acid Sulphuric acid Per cent. Per cent. Brown oil was found to contain. . . . 0-05365 and 0-01010 Light brown oil was found to contain . . . 0-07890 „ 0-08595 Pale oil was found to con- tain .... 0-09185 „ 0-07100 Phosphorics and Sulphur. — In order to deter- mine whether phosphorus and sulphur were present in cod-liver oil, either in a free state or in an organic combination, a certain quantity of the oil was oxidised with concentrated nitric acid and the amount of phosphoric and sul- phuric acids in the oxidised fluid determined by the above method. More phosphoric acid was found in the oxidised oil than in the non- oxidised, the difference denoting the amount of free phosphorus in the oil. Brown oil contained . 0-00754 % of such phosphorus Light brown oil contained 0-01135 „ „ Pale oil contained . . 0-02125 „ „ Lime, Magnesia, cmd Soda — These were determined by incineration of the oil and ex- traction with hydrochloric acid. The phos- phoric acid was precipitated with ferric nitrate and ammonia, and the precipitate filtered off and washed. The filtrate and wash-water were precipitated with ammonium oxalate, and the caldv/m oxalate formed was filtered and deter- mined. Magnesia was precipitated from the filtrate with ammonium phosphate, and to the filtrate from this, ferric nitrate and ammonia were added, precipitating the phosphoric acid. This was removed by filtering, the filtrate acidulated with sulphuric acid, evaporated to dryness, and incinerated, whereupon the per- centage of soda was determined. Potassium and iron were not present. Calcium Oxide Magnesia Sodium oxide Brown oil contained . Light brown oil contained Pale oil contained . % 0-0817 0-1678 0-1515 % 0-0038 0-0123 0-0088 % 0-0179 0-0681 0-0554 Tabulated Anaiysis Brown oil ■ Light brown oil Pale oil Oleic acid wifk brown sub- stance (gaduin and two peculiar compounds) . 69-78600 71-75700 74-03300 Margaric acid .... 16-14600 16-42100 11-75700 Glycerin 9-7H00 9-07300 10-17700 Acetic acid .... 0-12606 0-04571 Butyric acid . 0-16876 0-07436 Fellic and ohoUo acids, to- gether with imdissolved olein, margarin, and bili- fulTin 0-29900 0-08200 0-04300 Bilifulvln, bilifellio acid, and two peculiar substances 0-87600 0-44600 0-26800 A peculiar substance soluble in alcohol 30° . . . 0-03800 001300 0-00600 A peculiar substance in- soluble in water, alcohol, and ether .... 0-00500 0-00200 0-00100 Iodine ' 0-02950 0-04060 0-03740 Chlorine with some bromine . 0-08400 0-16880 0-14880 • Phosphoric acid 0-06366 0-07890 0-09136 Sulphuric acid 0-01010 0-08696 0-07100 Phosphorus 0-00754 0-01136 0-02126 Calcium oxide .... 0-08170 0-16780 0-16160 Magnesia 0-00380 0-01230 0-00880 Sodium oxide . 0-01790 0-06810 0-05640 Iron traces Loss 2-66700 2-60319 3-00943 lOO'OOOOO 100-00000 100-00000 De Jongh supposes that Marder's green soft resin is a mixture of bile-constituents, some Ixxvi CHRONOLOGICAL SYNOPSIS olein, and margarin, and that the hard resin soluble in alcohol consists principally of bili- fulvin and bilifellic acid. 1851. — Per Sonne (M&moire presenUe d I'Academie Nationale de MSdedne, 1851), like deJongh, found more iodine in the light brown than in the pale oil. He supposed the element to be present in the liver as potassium iodide, and to be set free by the joint action of air and fatty acids (produced by a. partial decomposition of the oil). It then acted upon the fat by sub- stituting the hydrogens in the same way as chlorine or bromine. He found no trace of pJionphorus. Oil in which this element has been found must have contained liver paren- chyma in suspension, this being the source of the calcium phosphate found. 1852. — Riegel (Arch. d. Phcmn. cxx. 48; Jahresb. d. Ohemie, 1852, p. 707) tested pale, Ught-brown, and brown oil for sulphw, phosphorus, iodi7ie,bromine, chlorine, sulphwric and phosphoric adds. The following percentages were ob- tained : — Brown oil light brown oil PaleoU Sulphur . Phosphorus Iodine Bromine . Chlorine . Sulphuric acid Phosphoric acic 0-0160 0-0090 0-0350 0-0037 0-1020 0-0475 0-0632 0-0180 O-014O 0-0405 0-0048 0-1133 0-0690 0-0753 0-0200 0-0205 0-0327 0-0045 0-1120 0-0640 0-0710 1853.— Winckler (Arch. d. Ph. cxxvi. 185) inferred from his researches that by saponifica- tion of the oil oleic and margaric acids and propyl oxide were formed, but not glycerin. By dis- tilling the soap with a solution of caustic potash he obtained arrwnonia and a trace of trimethyl- a/mine. 1856. — Luck (Jahresb. d. Ghemie, 1856, p. 490) found that cod-liver oil on being warmed, and subsequently cooled to 5°, deposited a sedi- ment consisting of small crystalline flakes of a fatty acid. This he purified by saponification, precipitation of the aqueous solution of the soda-soap with lead acetate, washing the dried precipitate with ether, decomposition of the residue with hydrochloric acid, and recrystal- lisation from alcohol of the fatty acid thus obtained. This acid had m.p. between 63° and 64°, and remained plainly crystalline at 60°. He gave it the nam^ of gadinie add, and by the ultimate analysis of its barium and silver salts found its empirical formula to be OggH^jOj. The discoverer took this to be the solid fatty acid in cod-liver oil. Berzelius (Pereira : Elements of Materia Medica, ii. 779) was struck by the analogy be- tween the reactions of de Jongh's gaduin and bilifulvic acid, and was inclined to suppose that gaduin was originally bilifulvic acid, and that the reddish-brown substance insoluble in alcohol and in water which he (Berzelius) • prepared from bilifulvin by numerous and protracted operations was nothing but the insoluble modi- fication of gaduin. 1862. — Nadler (Jahresb. d. Ghemie, 1862, p. 64) determined the percentage of iodine in various oils, and found that light-brown oil contained least, water-white (probably steam- prepared) oil somewhat more, and de Jongh's oil (light brown oil) most iodine. The first two varieties contained iodine as a component of the fatty acids, while in the latter it was present both in the soap and in the under-lye. 1865. — Oswald Naumann (Arch. d. Heil- hunde, 1865) found that cod-liver oil dialysed quicker, rose higher in capillary tubes, was more easily oxidised than neat's-foot oil, and he showed by experiments made on living cats that it was 1*8 times more readily absorbed. 1869. — Carl Schaper (Wiggers, Rufem. Jahresb. d. Ph. 1869, p. 340) examined La- brador oil. It was of a pale wine-yellow colour, had a peculiar odour of fish, sp. gr. 0-9219 at 8°, was perfectly clear at 15°, deposited a solid fat at 6°, and at — 2° solidified to a thick oleaginous mass. It was neutral to test-paper, but slowly exhaled a minute quantity of a volatile fatty acid which coloured litmus-paper • a wine-red. The oil was soluble in all proportions in ether, CHRONOLOGICAL SYNOPSIS Ixxvii but only slightly in alcohol. Heated with a solution of caustic soda it gave off. a faint but distinct smell of trimethylawdne and subse- quently of ammsnia. The soap thus formed was treated with sulphuric acid, the fatty acids removed, and the under-lye heated, when, first the smell of acetic add was distinctly recognis- able, and then that of huiyric acid : about 10 per cent, of glycerin (CgHigOg corresponding to 7 per cent, lipyloxide, OgHj^Og ; compare analysis below) was obtained. The fatty acids formed a yellowish, soft, butter-like mass, still smelling of fish. The component parts were by analysis found to be palmitic and elaic (oleic) acids only, in the proportion of 1 : 2'7 ; the palmitic acid contained a little stearic acid. Schaper tabulated the percentage of constituents of the fatty acid mass as follows : — Palmitic acid 25-511 Elaic acid 68-574 Lipyloxide (CjHioOs) . . . 5-915 100-000 From this result Schaper concludes that cod- Uver oil is a mixture of palmitin and elain (olein) . He points out that the oil on treatment with concentrated sulphuric acid turned a beautiful purple, and later a brown, from which he inferred the presence of bilia/ry matter, but did not extend his examinations farther. On the other hand, he found the percentage of iodine to be 0-015, and that of chlorine 00016. 1880. — Maumeng (Gompt. revd. xcii; 721) found that drying oils when mixed with sul- phuric acid evolved a greater quantity of heat than other oils, and also that the maximum temperature for each oil was always the same when the experiments were carried out under the same conditions. He mixed 10 c.cm. of cone, sulphuric acid with 50 grammes of oil, stirring quickly with a thermometer until the mercury began to fall. The difference between the original and the highest temperature was the measure of heat evolved. For steam-prepared oil the difference was found to be 103° „ brown oil ,, » » °^ " 1882.— P. Carles {Ph. Oenf/ralh. xxiii. 279 ; Jown. de Ph. et Oh. v. 145) demonstrated experimentally that the phosphates are present in solution and not in suspension, and that the percentage is greater the darker and more acid the oil is. On the other hand, a freshly prepared, filtered, and neutral oil does not contain even a trace of phosphorus compounds. For his ex- periments he employed absolutely neutral, fresh, and filtered oil ; liver parenchyma from which all fat had been removed by pressure and boiling ; and the free fatty acids obtained from the potash soap of the same pure oil by de- composition with hydrochloric acid. One hundred grains of oil and 7 gr. of parenchyma were introduced into one flask; 10 gr. of oil, 7 gi". of parenchyma, and 10 gr. of fatty acids into another; and the same quantities with 20 gr. fatty acids into a third flask. After being allowed to digest on a hot water-bath for several hours, each sample was filtered separately and decomposed by aqua regia poor in hydrochloric acid ; and the phos- phoric acid in the residue was then titrated with a solution of uranium. In the first case no trace of phosphorus was found „ second case 0-0022 gr. „ „ „ third „ 0-0074 „ From these results Carles infers that the percentage of phosphorus in the brown varieties of the oil is dependent on the amount of acid which they contain, because the phosphates of the tissue have been dissolved in proportion to the amount of acid contained. Starting from the observation that no iodine is found in fresh oU, while it is present in the acid brown oil in proportion to its colour and acidity, the author concludes that the cause of its presence is the same as that of phosphorus. In the fermentation process formerly in use, the livers were exposed to the air, and the higher temperature thereby created caused the oil to absorb oxygen in the form of ozone, which is capable of isolating iodine from the alkaline earths contained in the liver paren- bcsviii CHRONOLOGICAL SYNOPSIS chyma. It is this iodine which in the nascent state combines with the fatty compounds. Carles maintains that neutral filtered oils are entirely free from phosphorus and iodine ; when other investigators such as Graeger, Wackenroder, de Jongh, and Mitch. Bird (Ph. Journ. February 1882) have found iodine, it must be supposed that they have had less pure material for their experiments, or else that the potash they employed was not free from iodine. 1883.— Schadler (Technohg. d. Fette, 2nd ed. i. 773) recommended the solubility of cod- liver oil in boiling alcohol as a means of distinguishing it from other oils. In 100 parts of alcohol there are soluble 4 parts of cod oil, 7 parts of cod-liver oil, 15 parts of seal oil, and upwards of 100 parts of whale oil. But even- tually great differences were found in the solu- bility of cod-liver oil. Stanford (Br. Pharm. Conference, 1883 ; Ph. Journ. and Trans. No, 679, p. 353).— Most of the published analyses of cod-liver oil are much too high in the amount of iodine found. Six specimens were examined by the method used for kelp. The results were as follows : — Percentage of iodine Pale cod-liver oil . Norwegian oil Scotch oil . English oil . Newfoundland oil Light-brown oil . 0-000410 0000434 0-00027fi 0-000138 0-000315 0-000360 Herrings contain four times the amount of iodine found in cod-fish. 1884.— Kremel (Ph. Centralh. xxv. 337) studied cod-liver oil with a view to determining characteristic marks of distinction between cod- liver oil, Japanese oil, coal-fish oil, and seal oil. He has .tabulated the results obtained as follows : — "^ Sp.gr. Per cent. of fluid fatty acids Per cent of solid fatty acids M.p. of solid fats Acid value Saponific value Iodine absorption 1 Cod-Uver oil, 1884 0-62 171 131 2 9212 6-72 — 1-41 171 127 3 2-06 — 126 4 Cod-liver oil, 1883 88-88 7-55 50°-5 2-23 189 127 5 __ — — 2-32 — 128 6 90-46 6-88 51° 2-86 179 131 7 Cod-liver oil about 5 years old . . . 0-922 to 0-927 — — 1-47 178 140 8 Cod-liver oil about 10 years old, in badly \ corked bottles / — — 28-67 — — 9 Cod-liver oil about 10 years old . — — 5-03 — 129 10 9-60 48-49° 9-59 173 139 11 — — — 11-29 174 138 12 13 11-57 173 141 ■Pale cod-liver oil, 1883-84 .... 92-72 5-25 52° 8-66 181 14 1 87-00 12-75 51-52° 6-78 181 135 15 — — — 10-46 — 136 16 0-925 75-32 19-04 55-56° 1-26 177 187 17 0-926 — 12-22 53° 1-23 177 137 18 ■Coal-fish-liver oil, 1883 .... — — — — 1-29 179 129 19 0-925 74-20 20-60 — 1-49 181 126 20 0-927 70-00 21-34 52° 1-68 181 123 21 Japanese (cod ?) liver oil ... . 0-908 87-60 10-52 50-51° — — 120 22 } Seal oil, 1883 0-925 85-02 10-23 57°-5 1-95 178 127 23 0-925 88-29 9-81 57° 2-01 179 128 The determination of solid and fluid fatty acids was carried out in the following manner : — The oil was saponified in alcoholic solution with caustic potash on a water-bath, neutralised with acetic acid, the alcohol evaporated, the soap dissolved in water and decomposed with a solution of subacetate of lead. The lead-soap washed with hot water and dried on a water- CHRONOLOGICAL SYNOPSIS Ixdx batli was separated by ether into a soluble and an insoluble part. The soluble plumbic salt contained the fluid, and the insoluble salt con- tained the solid fatty acids. In order to determine the amount of free fatty acids (the acid-value or the number of milligrammes of KOH necessary to neutralise one gramme of fat) the oil was dissolved in ether and titrated with an alcoholic solution of potassium hydrate with phenolphthaleln as indicator. Kremel found that a greater acidity was not attributable to rancidity, as the samples were all that could be desired in regard to this. He supposed that the acidity was dependent upon different methods of preparation. The saponification value, i.e. the quantity of KOH in milligrammes necessary for the saponification of one gramme of fat, was determined by Kottstorfer's method — a weighed quantity of fat is saponified over a water-bath with a titrated alcoholic solution of potassium hydrate in excess, and the excess is retitrated with a titrated solution of hydrochloric acid. The iodine absorption, i.e. the percentage of iodine which a fat absorbs, was determined by V. Hiibl's method — a certain quantity of oil dissolved in chloroform was set aside for two or three hours with v. Hiibl's iodine solution, and then the mixture was titrated with sodium thiosulphate. v. Hiibl's iodine solution consists of 25 grms. of iodine and 30 grms. of mercuric chloride dissolved in one litre of 95 per cent, alcohol, the amount of iodine being accurately determined by sodium thio- sulphate. Kremel examined the behaviour of different oils towards fuming nitric acid by adding three to five drops of the acid to ten to fifteen drops of oil. Steam-prepared oil OMd pale oil turn red at the point of contact, and upon being stirred rose-red ; after a little while, however, this colour changes to a lemon-yellow. Coal-fish-liver oil turns blue at the place of contact, and becomes brown on being stirred. The colour is retained for two or three hours, and then turns into a more or less pure yellow. Japanese oil behaves in a similar way, save that some streaks of red appear beside the blue colour. Ail these varieties give Pettenkofer's bile- reaction, turning purple when treated with concentrated sulphuric acid. Seal oil was not affected by the addition of fuming nitric acid at first, but after a consider- able time it turned brown. Kremel found the reaction with fuming nitric acid so characteristic that by its aid he was enabled to detect an addition to cod- liver oil of 25 per cent, of any of the above- named oils. Rossler (Brogisten Zeitung, 1884, No. 10) agitated cod-liver oil with concentrated aqua regia, forming a dark greenish yellow unctuous mass which in half an hour turned brown and remained so. Seal oil assumed a pale yellow colour. 1885.— Jean (Monit. Scientif. 1885, p. 892) found that 6 per cent, of the oil consisted of a light yellow oily unsaponifiable substance which is coloured brilliantly red by a drop of sulphuric acid. He also examined the increase in weight of cod-liver oil when exposed to dry air over sulphuric acid, and found that after three days it had increased 6'383 per cent. Allen and Thomson (from Benedikt's Analyse d. Fette, 2nd edition, 869, shortly mentioned in Allen's Analysis) pointed out that cod-liver oil contains from 0-46 to 1'32 per cent, of chole- sterin, obtained by saponification of the oil and extraction of the soap with ether. Eecrystallisa- tion from alcohol of the substance soluble in ether produced the characteristic plates of cholesterin. •Hager (Ph. Gentralh. xxvi. 13) has made researches as to the detection of adulterations in cod-liver oil, and found the following tests sufficient. When vigorously shaken with litmus tincture, steam-prepared oil of the best quality should retain the blue colour for at least an Ixxx CHRONOLOGICAL SYNOPSIS hour; slightly inferior or the best kinds of yellow oil show the red colour within ten minutes, while still more inferior oils colour red immediately. The Reaction with Concentrated Sulphuric Add. — Eight to ten drops of the oil are dissolved in 2 c.cm. of chloroform, and two drops of the sulphuric acid are added. The mixture when agitated assumes a light violet colour, imme- diately darkening and changing into a perman- ganate red, brownish red, dark brown, and finally blackish brown. When one volume of the acid and two volumes of the oil are shaken up and allowed to stand for three or four hours a dark and rather stiff, unctuous mass is formed. If other fish oils are present the consistency of this mass is less firm and somewhat like vaselin. The elaidin test with nitric acid, sp. gr. 1'185, and a few copper filings invariably gives the same result — with genuine oil. No special change is noticeable in colour, nor is any deposit formed even after being kept for two or three days at a temperature of 7°-10°- A layer of elaidin is yellow with a reddish -brown tinge, clear or slightly turbid, and less viscous than cod-liver oil. Separations in the oily layer denote the presence of foreign fats. Saponifi- cation of the oil is effected by mixing 7 "5 grms. of the oil with 15 c.cm. caustic soda solution, sp. gr. 1*160, and 5 c.cm. water, slightly boiling four or five times, while constantly agitating the mixture. The saponification, however, is not complete, and therefore when the soap mixture has been set aside, first in a warm place for some hours, and then in a cold place, the mass will be found to consist of two layers, the top one being whitish and stiff, and the lower, transparent. The latter forms the larger part, and is the almost colourless fluid oil-like soap. Where foreign oils or resins are present this layer is merely translucent and not fluid. Adulteration . with vaselin can be detected by the specific gravity, that of the oil varying between 0-920 and 0-930, usually from 0-922 to 0-925. To the practical chemist the squeaking sound produced by turning the cork moistened with oil in the neck of the bottle will betray the presence of mineral oils. To demonstrate chemically the presence of these oils is a difficult matter. Boudard's nitric acid test is not reliable if the oil contains less than 15 per cent, of foreign fish fats. From 15 to 20 drops of nitric acid (sp. gr. 1-480-1-500) are added to 2 c.cm. oil, whereupon genuine oil gradually assumes a carmine colour. An adulteration with resin will increase the specific gravity, and on saponification of such an oil the soap layer will be turbid and not transparent. The resin might be extracted from the oil by boiling and agitating it with dilute alcohol. The presence of lead, which may arise from neutralisation of the oil with lead oxide, may be detected by extraction with dilute acetic acid, and neutralisation and precipitation with sulphuretted hydrogen. 1887.— Salkowsky (^eifecfe. /. anal. Ghemie, xxvi. 1887) examined several methods in- tended to distinguish liver oils from vegetable oils. Determination of Solidifying a/nd Melting Points. — The temperature at which cod- liver oil solidifies was found to be rather low, but the. several varieties, all undoubtedly pure oils,*/ differed very much in this respect. While some remained fluid even at — 15° others solidi- fied at 0°. The melting point of congealed oil also varied considerably, being in five cases at or above 0° and in six others below 0°. Moreover it was found that the time of exposure had a great influence on the solidifying point : one sample stated to be non-congealing at —15° remained for some little time clear at that temperature, but solidified thoroughly at — 4° if kept at that temperature for hours. In spite of these irregularities it was possible when the oil rapidly solidified at 0° to detect an admix- ture of 20 per cent, of palm oil, cocoa-nut oil, or palm-seed oil. Salkowsky believes that differences in the solidifying points of the oils CHEONOLOGIOAL SYNOPSIS Ixxxi arose from the fact that the fats which solidify at lower temperatures had been removed from some of the oils before they had been put on the market. All the samples congealed when exposed to a temperature of —10° to —12° for 2^ or 3 hours. The Reichert-Meissl method has been devised to determine the saturation capacity of the vola- tile acids which may be contained in an oil. It consists in the alcoholic saponification of the oil with caustic potash, evaporation of the alcohol, solution of the soap in water, and de- composition by dilute sulphuric acid ; 100 com. are then distilled off and the distillate titrated with -^ n. alkali solution. Salkowsky found the requisite quantity of solution calculated for 5 grms. oil to be O'lO to 0"20 c.cm. Other oils require perhaps a little more, except cocoa-nut and palm-seed oils, which require as much as 7'28 and 3-48 com. respec- tively. These are the only two oils that can, therefore, with any degree of certainty be detected in cod-liver oil, and then, only provided they be present in considerable quantities. The reaction with cholesterin, phytosterin, and sul- phuric acid was made in two different ways : by adding the acid direct to the oil ; and by dissolving the oil in chloroform, adding the acid and shaking. The latter method is the better, as the colour is more stable. The mixture assumes first a violet colour, which is gradually changed into purple, reddish brown, and lastly dark brown. This remarkable and well-known reaction has been supposed to indicate the presence of biliary matters in cod-liver oil. BuCHHEiM has, however, demonstrated that cod- liver oil does not contain any biUwry acids or bile pigments, and, further, the chief pigment of the bile does not give the above reaction, nor is it to be detected in cod-liver oil. On the other hand this sulphuric acid reaction of the oil has some resemblance to that of cholesterin in choloroform solution. In order to throw some light upon this matter the oil was saponified with an alcoholic solution of caustic potash, the alcohol evaporated, the soap dissolved in a large quantity of water, and the strongly alkaline solution shaken with ether. After separation and evaporation of the ether, a crystalline yellow substance re- mained which when recrystallised from alcohol formed a dazzling white crystalline mass of cholesterin with m.p. 146°. The solution in chloroform was colourless, and gave the typical reaction with sulphuric acid without a trace of blue colour at the beginning of the reaction. The percentage of cholesterin in the oil was found to average 0'3. The purple violet chloroform solution which floated upon the sulphuric acid became almost colourless or intense blue (sic) when diluted with more chloroform, but assumed the purple violet colour again upon being shaken. Salkowsky supposed this to arise from water contained in the chloroform. The above-mentioned crystalline yellow substance left by the evaporation of the ether, dissolved, without application of heat, In chloro- form, forming a perfectly clear golden yellow solution, which upon addition of sulphuric acid assumed a beautiful indigo blue colour, rapidly changing, however, into purple violet. Pure cholesterin, as it was obtained by the above- mentioned recrystallisation from alcohol, is never, like the yellow substance, coloured blue by sulphuric acid ; consequently this yellow colour and the indigo blue reaction must be attributed to the presence of a colouring matter , which cannot be a bile pigment because it is not extracted from the chloroform solution by shaking it with a solution of sodium carbonate, but must belong to the class of lipochromes examined and studied by W. Kiihne. To the alkaline solution, obtained after the soap had been dissolved in water, the solution shaken with ether and ethereal extract of cholesterin and lipochrome removed, sulphuric acid was added in slight excess and the mix- ture again shaken with ether. After separation the ether was evaporated and the residue heated for some time on a water-bath. In this way the fatty acids were obtained. To a chloroform solution containing 5 to 8 per cent, of these acids Ixxxii CHRONOLOGICAL SYNOPSIS an equal volume of sulphuric acid was added, when the latter was immediately coloured a deep brown, appearing dirty green in reflected light. Pouring off the colourless chloroform after the lapse of half an hoar and adding a few drops of the sulphuric acid to some c.cm. of glacial acetic acid, the solution assumed after one or two hours a beautiful reddish violet colour with a dirty-green reflection, and maintained this colour for several days. Thus cholesterin, lipochrome, and fatty acids are the constituents which play a part in the well-known colour reaction with sulphuric acid. The only other pigment producing a blue colour with sulphuric acid was found in palm oil, and a trace of it in cotton-seed oil. Salkowsky found that the cholesterin of cod-liver oil was not identical with that of the vegetable oils, the latter being much more like phytosterin as described by Hesse in 1878. Cholesterin forms a thickish mass of crystalline flakes, while phytosterin forms bushy groups of needles. Phytosterin, slowly crystallised, forms beautifully developed lengthy hexagonal plates, which is never the case with cholesterin. Phytosterin melts at 132°-134°, whereas ike melting point of cholesterin is 146°. These differences are sufficiently characteristic for proving the presence of vegetable oils in cod- liver oil, the microscope being of great assist- ance in such examinations. Phytosterin dis- solved in chloroform also gives a colour reaction with sulphuric acid, but the colour is more bluish than the cherry-red of cholesterin. None of the fatty acids from vegetable oils when dissolved in chloroform behaved towards sulphuric acid and glacial acetic acid like the fatty acids of cod-liver oil as described above. Linseed and palm oil gave a faint indication of a similar behaviour. Salkowsky, like Hager, found the free fatty acids were present in the better varieties of cod -liver oil, in only quite insignifi- cant proportions, i.e. from 0'25 to 0-69 per cent. ; in only one sample was there found as much as 6'5 per cent. Most vegetable oils contained larger quantities. 1888. — Van der Burg {JEncyelop. d. gesammt Ph. 1889) found after incineration of the pale oil merely a trace of ash, not sufficient for deter- mination by weight. In 22 grms. of de Jongh's oil he found 0-002 grm. of ash, containing cal- cium and iron. Hirsch (Encyohp. d. gescmvmt Ph. 1889) gives the solubility of the light-coloured oils in cold alcohol as 1 in 40, in warm alcohol as 1 in 31-32 ; of the light brown oils in cold alcohol as 1 in 31-36, in warm alcohol 1 in 13, and of the brown oils in cold alcohol as 1 in 17-20. In ether, cod-liver oil dissolved readily, e.g. in ether of sp. gr. 0'728 in less than twice its quantity ; in chloroform and carbon disulphide it also proved readily soluble. Gautier and Mourgues (Les AlcaUndes de ■I'Huile de Foie de Morue) examined the various cod-liver oils, and found in light-brown oil a small quantity of leucomaines, but not in the lighter oils. One hundred kilos, of madeira-coloured (light-brown) oil was shaken with its own volume of alcohol (35 per cent.), containing 3 grms. of oxalic acid per litre. In order to pre- vent oxidation the air in the bottles employed in the process was replaced by carbonic acid. After standing for some time the alcoholic ex- tract was drawn off and almost neutralised with milk of lime, after which it was filtered and distilled in vacuo at a temperature of 40°. When the liquid had been reduced to one- twentieth of its original volume, the distilla- tion was discontinued ; the clear and slightly coloured liquid was saturated with calcium car- bonate, filtered, and distilled in vacuo to dryness. The residue was treated with 80 per cent, alcohol, the extract filtered, the alcohol evapo- rated, and the liquid concentrated in vacuo to a syrupy fluid from which the bases were separated by the addition of dry potassium hydrate, and extracted by shaking with ether, from which they were precipitated by an ethereal solution of oxalic acid. The precipitate was washed CHRONOLOGICAL SYNOPSIS Ixxxiii with ether and dried. From 100 kilos, of oil 52 grms. of oxalates were obtained almost colour- less and perfectly soluble in water. The bases were then isolated by dissolving the oxalates in a little water and adding potassium hydrate, when they appeared as a thickifih brown floating layer, which was removed and dried over freshly fused potassium hydrate. Fifty- two grms. of oxalates gave 26*5 grms. of free bases. Subjected to fractional distillation, first under atmospheric pressure, afterwards under diminished pressure on an oil-bath, they separated into several volatile and non-volatile The first fraction which boiled at 87°-90° under a pressure of 770 mm. was butylamine, and constituted one-sixth of the whole. The ultimate analysis corresponded to the formula C,H„N. The boiling point of the second fraction was between 94° and 100° under the same pres- sure (770 mm.). It consisted of amylwmins, C,Hj3N, and constituted one-third of the whole. The third fraction boiled under the same pressure between 100° and 115°, and proved to be heocylamine, CgHjjN. . It fornjed but an in- considerable part of the constituents. The fourth fraction boiled at 100° under a pressure of 60 mm., and at 198°— 200° under 770 mm. pressure. It was dihyd/rolutidine, OjHj,N, and constituted one-tenth part of the bases. The residue from the distillation constituted the non-volatile bases. Treated with dilute hydrochloric acid and precipitated with plati- nous chloride, the precipitate was decomposed with sulphuretted hydrogen and again precipi- tated with caustic potash. Dried on unglazed tiles it was found to be asseline, CjjHj^N, and constituted barely one-fifteenth part of the The mother-lye from the platinum salt of asseline was evaporated, depositing a platinum salt from which, by decomposition at a higher temperature with sulphuretted hydrogen, there was obtained a chloride of morrhuine. The base morrhuine, OigHj^Nj, was isolated with caustic potash, and by extraction with ether. It formed one-third part of all the bases. After the bases had been extracted from the alkaline syrupy fluid by shaking with ether in the manner above described, the residue was examined in search of the acids with which the bases had probably been combined in the form of salts. After adding a little sulphuric acid the following acids were obtained. 1. An acid which, especially on the applica- tion of heat, appeared as a brown sticky mass, capable, however, of crystallisation. It was a pyridine compound, and received the name of morrhuic acid, OgHjjNOj. One litre of oil contained one gramme of this body. 2. After the separation of morrhuic acid, the liquid was distilled, and in the distillate were found formic and butyric acids. 3. In the residue there remained^ — a. A small quantity of morrhuic acid, which was removed by alcoholic ether. b. A certain quantity of phosphoric acid originating from phosphates, phosphorgly- cerins, and lecithins. c. A little sulphuric acid of the same origin. 4. After the separation of these substances tho remainder was precipitated with basic lead acetate, filtered, the lead removed with sulphu- retted hydrogen, evaporated, and extracted with 98 per cent, alcohol. After the evaporation of the latter the liquid was distilled in vacuo. In the part of the distillate which boiled at 180° glycerin could be identified by its being con- verted into acrolein. 1889.— Unger (8udd. ph. Zeit. 1888, p. 98, and 1889, p. 241) prepared three kinds of oil through putrefaction. The first oil drawn off" from the livers had a light yellow colour, sp. gr. at 14°= 0-928; 1-69 per cent, free but not volatile acid ; the second oil obtained from the same livers during the progress of putrefaction contained 4*78 per cent, free non- volatile acids ; e 2 Ixxxiv CHRONOLOGICAL SYNOPSIS the third oil was the last one obtainable, and was the darkest in colour. It contained 7-33 per cent, free acids (trace of propionic acid) and had a sp. gr. of 0-929. After standing for four hours in contact with nitric acid (sp. gr. 1'4) in a test-tube the first oil gave a cloudy ring of albuminates in combination with iron man- ganese and phosphorus ; the other two gave no such reaction ; still albuminous substances were present in them though in another form. The albuminous substances could be extracted from the oil by shaking with water in which they are soluble. Those extracted from the first oil smell of trimethylamine when boiled with water ; the others do not. Unger concludes that the first oil is the only sort that should be employed as a medicine; about the second he is doubtful ; the third oil he considers injurious. The following researches on cod-liver oil are yet to be mentioned. Grace Calvert's colour reactions (Benedikt's Anal. d. Fette, 2nd ed., p. 306). sp.gr. Caustic soda 1-340 colours ood-liver oil dark red Sulphuric acid 1-475 91 purple 1-530 )» )» j» »» 1-635 IT intense brown Nitric acid . 1-180 ti red j» • 1-220 »» pink »i 1-BBO »* red Phosphoric acid • • »» fl dark red Nitric acid mixed with sulphuric acid • • » *» dark brown Agrua regia . • • » j» yellow Nitric acid of sp. gr. 1-33 and afterwards caustic soda of sp. gr. 1-34 form a fluid mass. Aqua regia and afterwards caustic soda of sp. gr. 1'34 form a fluid orange-yellow mass. Allen (Benedikt's Anal. d. Fette, 2nd ed., p. 368) found the saponification value of cod-liver oil to be 182-187. Valenta found it to be 171-189. Dieterich found the saponification value of the acids to be 204-4. Chevallier and Baudrimont (KjUnig's Analyse d. Nahrungs- und Geniissmittel) give the consti- tuents of cod-liver oil as follows : — Ole'ln Margarin Sulphur Phosphoraa Iodine Bromine Chlorine Sulphuric and phosphoric acids White oil? (heller Leber- thran) .... Pale oil .... Brown oil' . 98-87 98-87 98-80 0-81 0-81 0-93 0-320 0-019 0-016 0-020 0-020 0-019 0-033 0-032 0031 0-004 0-004 0-003 0-112 0-112 0-102 0-089 0-092 1893.— Dr. W. Fahrion (Ghem. Ztg. xxv. 434) assumes that the changes taking place in oils with high iodine absorption are caused by polymerisation. Unsaturated acids, on account of their double bonds, are strongly disposed to combine with other bodies, and when such are not present they will combine mutually. In the case of hydroxy-acids, however, the pro- cess is not a polymerisation but a condensa- tion through the hydroxyls combining under elimination of water, leaving the double bonds undisturbed. As a consequence of such changes specific gravity, acid-value, and percentage of hydroxy-acids will increase, but iodine absorp- tion will decrease. Thus he found the following changes to have taken place during the increas- ing age of a sardine oil : — — Specific gravity Iodine absorption Acid- value Hydroxy- acids Original oil After six months After a year 0-933 0-936 0-943 193-2 179-7 163-6 20-6 25-3 31-7 0-6 1-1 4-8 The free unsaturated acids must be con- siderably more disposed to polymerisation or condensation than their glycerides, and no reliable conclusions can, therefore, be drawn from the examination of their acid-value and iodine absorption ; indeed the researches on the free fluid acids of the above-mentioned sardine CHRONOLOGICAL SYNOPSIS Ixxxv oil proved the correctness of this assmnption. Prepared at different times these acids gave the following values : — Iodine absorption Ada-value Molecular weight I. II. TTT. IV. 229-4 219-6 198-0 74-4 189-4 179-8 174-7 100-0 295-7 311-5 320-6 660-0 The saponification value would naturally be expected to remain unaffected by the polymeri- sation and condensation processes which in- fluence the other values so much. But even for this value no constant results could be obtained : they varied from 159-5 to 417-2, according to the time the alkali was allowed to act upon the free acids of the sardine oil. Dr. Pahrion concludes from this behaviour that the acids are split up through oxidation into other acids of low molecular weight. He experi- mentally shows that oleic acid by the action of potassium permanganate produces acetic and oxalic acids, besides a mixture of other homo- logous acids, the presence of which also he could demonstrate when the oleic acid was simply shaken with an alkali solution for three days. The acids from sardine oil showed analogous behaviour, but the volatile acids appeared in much larger quantities in both reactions. Instead of ascertaining the iodine absorption of the oil-acids directly, Dr. Fahrion thought the results might be more correct if the solu- tions of the acids were first neutralised, because he had found that the polymerisation of the unsaturated acids was undone when they were saponified. In this way he obtained the follow- ing figures :- Ordinary Neutral method Bolution Japanese oil . 96-0 138-7 Cod-liver oil . 147-9 195-7 Sardine oil . . 193-2 216-6 Eioinole'io aoid . . 82-9 Oleic acid . . . 75-5 Fluid acids from sar- dine oil . . . 229-4 102-9 102-2-107-0 240-7 It will be seen that the figures for oleic acid vary considerably when determined in a neutral solution, and are much higher than those theoretically correct (90-07), whereas the results as determined by the ordinary method are much too low. Dr. Fahrion therefore arrives at the conclusion that the methods hitherto in use are. not reliable when hydroxy- aoids are present, and proposes a method by which such acids are removed before the de- termination of iodine absorption. The method consists essentially in freeing the non-hydroxy- lated from tbe hydroxy lated acids by the- in- solubility of the former in petroleum ether. Dr. Fahrion (Ohem. Ztg. 1893, xxx. 621).— Physetoleic acid is generally supposed to be a characteristic constituent offish oils, but so far as Dr. Fahrion has been able to determine it is found in sperm oil only, and not in any of the liver oils. If, however, it is a constituent of these, it must be in company with other unsaturated aliphatic acids, as is evident from the iodine absorption, which varies in different liver oils from 100 to 200, but mostly from 130 to 160, whereas the triglyceride of physetoleic acid has an iodine absorption of 94-9 only. With a view to dis- covering physetoleic acid in sardine oil. Dr. Fahrion examined it by the method described above, and found the fluid non-hydroxylic acids to consist chiefly of an acid isomeric to linolenic and isolinolenic acid of the formula G^fi^Jd^, of oily consistence and not solidifying in the cold. The different determinations gave the follow- ing figures, but he seems to admit that they more represent a selection made for the pur- pose than an average of all the results ob- tained. H Iodine absorption Acid-value SapoBif, value Barium salt Calcium salt Magnesium salt Found .... Calculated on GuHjoOj . • 78-03 77-70 11-28 10-79 229-4 273-0 189-4 201-4 201-9 201-4 19-88 % 19-83 % 6.63 6.73 4-25 4-15 Ixxxvi CHRONOLOGICAL SYNOPSIS This acid has consequently three double bonds, and Dr. Fahrion termed it jecorio acid. Next he examined the solid acid of sardine oil, and found it to consist solely of palmitic acid, of which there was present as palmitin 14-3 per cent., determined by oxidising the un- saturated acids in the mixture by potassium permanganate. According to the rule propounded by Hazura, jecoric acid ought to yield a hexa- hydroxy-stearic acid by oxidation with potas- sium permanganate. The fluid acids of sardine oil did not yield such an acid, but the result was a mixture of the lower homologues of the saturated aliphatic acid-series, among which carbonic acid was especially conspicuous. Dr. Fahrion explains this behaviour of jecorio acid by assuming that Hazura's rule holds good only as regards acids with a straight chain without branches, and that therefore jecoric acid must have a structure with side-chains, contrary to the opinion, hitherto entertained, that natural fatty acids never have side-chains. Dr. Fahrion {Chem. Ztg. 1893, xxxix. 684) found palmitic acid in one variety of whale oil, as well as in sardine oil ; and he then examined the solid acids in another whale oil, in Japanese oilj and in ordinary cod-liver oil. He prepared them by simply dissolving the acids in alcohol, exposing the solution to the cold, dissolving the crystalline mass thus obtained, and recrystallising it from alcohol until the colour was quite white. In this way he obtained from the oils mentioned solid acids with the respective melting points 54°, 61°, 66°, and 65°, and with the molecular weights 266-4, 260-6, 260-0, and 263-3. He concludes from these data that most fish and liver oils contain stearic in addition to palmitic acid, the latter, however, predominating. The so-called stearin from these oils is, he says, chiefly palmitin. Dr. Fahrion has further made parallel de- terminations of Japanese oil, cod-liver oil, and sardine oil, with the following results : — Japanese Cod-liver Sardine oil oil oil Sp^eifie gravity 0-916 0-927 0-933 Iodine-absorption . 96-0 147-9 193-2 Acid-value 31-2 15-8 20-6 Aihes .... traces traces traces Not saponifiable (ohole- sterin) . . 0-6 0-6 0-6 Total of fatty acids 95-3 94-9 94-5 Hydroxy-aeids 0-5 0-6 0-7 The fluid acids were - prepared from the barium salts through extraction by ether, and they were freed from hydroxy-acids, formed during the operations, , by petroleum ether as described before. A yellow rather thin oil resulted, and the following determinations of the acids thus derived from the three different oils were made : — Aoid- valne Iodine- absorption Ultimate analysis H Japanese oil-aoids Cod-liver oil-aoids Sardine oil-acids . Calculated on P„h:„0, „ 0,.H„0, 190-6 184-0 189-4 198-6 201-4 110-6 175-5 229-4 89-9 273-0 76-60 73-02 78-03 76-59 77-TO 11-89 11-53 11-28 12-06 10-79 Except in the case of the sardine oil-acid, which according to Dr. Fahrion's earlier researches described above contains nearly exclusively jecoric acid, the ultimate analyses are rather purposeless, because evidently we have here to deal with mixtures of different acids. Dr. Fahrion says that jecoric acid is present in con- siderable quantities in cod-liver oil,' and that the larger percentage of hydrogen in these acids com- pared to those of sardine oil corresponds to the lower iodine-absorption. He further states that from the percentage of oxygen in the fluid acids the conclusion may be drawn, with considerable certainty, that the fresh oils contain no hydroxy- acids. After having unsuccessfully tried to prepare ' It does not appear from the papers Dr. Fahrion has published that he has actually and experimentally demon- strated the presence of jecorio acid in any other oil but sardine oil. OHRONOLOGIOAL SYNOPSIS Ixxxvii the unsaturated acids, presumably present in cod-liver oil, by a method derived from the oxidation of fish oils in the process of chamois- dressing, Dr. Fahrion tried oxidation by potas- sium permanganate in alkaline solution. The acids thus hydroxylated from Japanese oil and insoluble in petroleum-ether were dissolved in a solution of sodium hydrate, precipitated by barium chloride, filtered at their boiling tem- perature, and to the filtrate was added hydro- chloric acid in slight excess. When cooled, white mother-of-pearl-like crystals, m.p. 114° separated. The molecular weight of this was found by titration to be 302-4. The undis- solved barium salt was decomposed by hydro- chloric acid, again dissolved in sodium hydrate solution, and precipitated with barium chloride. This process was repeated five times, and still flakes of crystals separated when the filtrate was concentrated by evaporation. These flakes had m.p. 114°, and proved to be identical with the above-mentioned similar crystals. The small quantity of undissolved barium salt which remained was decomposed, and the acids recrystallised from alcohol. Their melting point was found to be 115°, and presumably identical with the rest. Cod-liver oil and sardine oil were treated in the same way ; the product of oxidation from the former had m.p. 116°, mol. weight 304-9, and from sardine oil respectively 114° and 304-0. The yield from cod-liver oil was considerably smaller than that from Japanese oil, and from sardine oil still less. As there apparently could be no question of a mixture of different acids the determination by ultimate analysis was proceeded with, and the results were — — H Molecular weight Pound Calculated for \ c„H,A . ; 67-50 67-86 67-55 11-13 11-39 11-26 1 302-4 1 302-0 This body, for which Dr. Fahrion proposes the name of asellic acid, is therefore the di- hydroxy-heptadecylic acid from a heptadecylenio acid OjjHjjOj not yet isolated. bcxxviii NEW CHEMICAL EBSBAECHES ON COD-LIVER OIL By p. M. HEYERDAHL The Feee Fatty Acids In the determination of the amount of free fatty acids in cod-liver oil, Dr. Franz Hoffmann's method ' was applied. Phenol-phthaleine proved useless as an indicator in titration, and rosolic acid had to be used in its stead. The process was as follows : — The oil, after being weighed — the amount varying from _ 7 grammes for oil containing small quantities of free fatty acids to 0'5 gramme for oil richer in these acids — was dis- solved in 20-40 c.cm. of ether previously neutralised by -j-oir*-'^ '^^ normal alcoholic solu- tion of caustic potash, also used in titration of the fatty acids. It must be freshly prepared, as on standing a short time it alters in chemical composition. It is best made by taking the quantity necessary for immediate use of an aqueous yV*^ normal solution of caustic potash, free from carbonic acid, and adding alcohol in the proportion of 1 to 10. If fat separates during titration more ether is added. As indicator a couple of drops of an alco- holic solution of rosolic acid (4 : 1 ,000) is used. During the titration exactly so much alco- holic solution of caustic potash is added to the liquid as will colour it a rose red. In the calculation of the acid-value the necessary correction must be made in case an acid ether or an acid alcohol has been used. By the acid- value is understood the number of milligrammes of KOH necessary to neutralise 1 gramme of fat. ' 'Beitrage zur Anatomie und Physiologie, 1874. With a view to determining the changes which the percentage of free acids of the oil underwent during the process of extraction from the livers, several samples taken from the oil at various stages of the process were examined by the above method. The free fatty acids, instead of increasing during the process, as one might have been inclined to expect, were actually found to decrease. Thus :— At the beginning At t\ie end of the process of the process 1. Acid-value . =0-76 which decreased to 0-58 2. „ . =0-99 „ „ 0-81 By continued heating of the samples and simultaneously conducting a current of air through them, the acidity was at first somewhat decreased, but later it steadily rose, though not rapidly. For instance, the acid-value of a sample after being heated 1^ hour on a water- bath, during which time a current of 52 litres of air was conducted through it, decreased from 0'81 to 0'75, but thereafter, during the next four hours, with an additional current of 155 litres of air, rose to 1"22. The other samples behaved in an analogous manner. For oil extracted from the liver by freezing (no heat whatever being applied) the acid-value was found to be 1' 38. Oil prepared by conducting the steam direct into the liver had an acid- value of 0*27. If a current of air was not conducted through the oil during the warming process the acid- value increased somewhat more slowly, though the difference was not great ; for instance, after HEYERDAHL: NEW CHEMICAL RESEARCHES Ixxxix 165 minutes' heating, the acid-value rose from 0-68 to 0-75. The influence of temperature upon the acid- value was exceedingly small. In a sample kept for over three hours, at a temperature of 243° 0., the acid-value rose from 0-72 to 077 only. Oil, rich in solid fats, had a smaller acid- value than oils from which they had been separated. The difference was 0-09. In oil, melted from old (not fresh) fish-livers, a higher acid-value was found — in one case 1*75, for instance. Oil melted from green (bilious) livers had an acid-value of 0'60. In oil that had been standing a long time the free acids remained unchanged in quantity, i.e. Oil from 1884 had an acid-value of 0*73 „ 1885 „ „ 0-74 „ 1886 „ „ 0-72 1887 „ „ 0-70 1888 „ „ 0-70 Several samples of raw medicinal oil were examined. Their qualities varied greatly, owing to want of uniformity in their preparation. The three samples indicated below varied in colour, odour, and taste : — • The lightest sample had an acid value of 7'38 A somewhat darker „ „ 7'55 The darkest „ „ 7-72 The acid-value of the pale oil was found to be 21"2, and of brown oU 54i'4. These oils, which are separated from the liver ■ by process of decay, thus show a very high acid percentage, which, of course, varies considerably, according to the quality of the oil. For oil obtained from other species of fish by the steam process the following acid-values were found : — Coal-fish {Qadits vvrens) oil had an acid-value of 0"34 Torsk (Brosmius brosme) „ „ 0-15 Ling {Molva vulgaris) „ „ 8-51 Starry Bay {Baia radiata) „ „ 9'34 Porbeagle {Lanvna cortwMca) „ „ 5'10 As will be seen, the free fatty acids of oil prepared from cod-livers by steam process are insignificant, the acid-value of 0-70 corre- sponding to 0-36 per cent, of oleic acid. The acid percentage is increased very little indeed by heating even to quite high temperatures, while, on the other hand, its colour darkens, and its rancidity increases with great rapidity. The free fatty acids have consequently no connec- tion with rancidity ; they are, however, greatly inclined to form during the decay of the liver, but neither during the application of heat nor through the influence of the air. Examination of Stearin The Trade demands that the finest medicinal cod-liver oil shall remain perfectly clear, and deposit no solid fats at low temperatures, some placing the limit at 0° C, and others still lower. The solid fats, which under the influence of cold are deposited by the oil, go under the common name of stearin, a white butter-like mass, which has hitherto been supposed to con- sist mainly of palmitin, stearin, and some olein, and the melting-point to vary according to the proportion in which these three glycerides were present. It would naturally be of interest to submit this so-called stearin to a closer examination, and to this end attempts were made to prepare the solid, free from the fluid glycerides, by re- peated crystallisations in ether, ether-alcohol, and petroleum-ether, v. Htibl's iodine-absorp- tion method was applied for determining the degree of purity of the crystallised substance. Stearic and palmitic acids are, as is well known, saturated compounds, which add no iodine from v. Htibl's solution, so that the more these were freed from oleic acid the less should be the iodine-absorption, until at last, when all oleic acid, in the form of olein, was washed away, the iodine-absorption should be 0. As a means of control, determinations of acid-value and melting-point were applied. The determination of iodine-absorption, accord- ing to V. Hiibl's method, was as follows : — The amount of oil used for each determina- tion varied from 0*2 to 0*4 gramme. In order always to have nearly equal weight, the same xc HEYBEDAHL: NEW CHEMICAL EESEAECHES number of drops of tlie oil were taken and these accurately weighed, dissolved in chloro- form in a 200 c.cm. bottle having a glass stopper. Chloroform was added in such quantity that the liquid remained clear during titration, as a rule 18 c.cm. being sufficient. The iodine solution was made by mixing 25 grammes of iodine, dissolved in 500 c.cm. of alcohol, with 30 grammes of chloride of mer- cury, also dissolved in 500 c.cm. of alcohol, and allowing the mixture to stand twenty-four hours. This solution was then added from a burette in such quantity that after standing two hours the dark brown colour still remained; 25 ccm. proved a proper amount. ' The mixture was set aside for a certain time, which for all samples must be the same in order to obtain comparable results — in this case two hours — at the expiration of which was added such quantity of a lO-per-cent. iodide of potassium solution that upon the admixture of 150 c.cm. of water, no iodide of mercury was deposited : 20 c.cm. of iodide of potassium solution proved sufficient. Lastly, the liquid was titrated with sodium thiosulphate solution during constant stirring until it assumed a light yellow colour, when a few drops of a fresh starch solution were added as an indicator; the titration with sodium thio- sulphate was then resumed, and continued until all colour disappeared. The shades of the liquid from the time of the addition of the starch solution until decoloration varied from a mossy green, through green, and bluish green to violet, from which point, a couple of drops only, of the sodium thiosulphate solution, were required to complete the process. In this manner were examined by way of a beginning : — 1. Steam-prepared oil from which the solid fats had been removed at — 7°. 2. Steam-prepared oil from which no solid fats had been removed. 3. The solid fats (so-called stearin), freed as much as possible by mechanical means from the liquid fats. For No. 1 the iodine-absorption was found to be = 142'6 For No. 2 „ „ „ =140-1 For No. 3 „ , „ =113-4 The inconsiderable diflference between the first two figures shows that the iodine-absorp- tion method is little adapted to determining the percentage of solid glycerides in the oil, and the last figure proves that the so-called stearin contains considerable quantities of iodine-absorbing matter. As before stated, the stearin had been ex- perimentally recrystallised from ether, ether- alcohol, and petroleum-ether. It seemed to crystallise best from the last-named solvent, but it retained an iodine-absorption of 97*7 after repeated crystallisation from this medium, and must therefore be supposed to contain still a considerable quantity of unsaturated com- pounds. As it would obviously be a rather impracticable way to obtain the solid fats by recrystallisation, the method was abandoned, and replaced by a process of isolating the solid acids, in order to obtain through them some knowledge of the solid compounds in the stearin. To this end 200 grammes of stearin were saponified with a 20-per-cent. aqueous solution of caustic soda in excess, added in small quan- tities during constant stirring and heating over a water-bath, and, later, over open fire 8^ hours. There remained an unsaponifiable residue. The under lye was now drawn oif, the rest warmed with 1,200 c.cm. of water, cooled, and set aside in a deep beaker glass. The unsaponifiable part, which separated as a white, butter-like floating mass, was removed and repeatedly washed with warm water, from which it was freed in a separating funnel. The substance now separated into two layers, the upper one yellow and butter-like, the lower rather whiter. Separated from each other and thoroughly washed with water whilst being heated over a water-bath, their iodine-absorp- tion was found to be — 1. The yellow butter-like substance = 119-1 2. The whiter substance = 116-2 or, both more iodine-absorbing than ' stearin.' HEYERDAHL: NEW CHEMICAL RESEARCHES xci Both were saponifiable with aloohoUe solu- tion of sodium hydrate. The soap was heated over a water-bath until the alcohol had eva- porated, and then decomposed with dilute sul- phuric acid. The free acids thus obtained were repeatedly washed with water until the washing water gave no deposit with BaClj, and then subjected to the iodine-absorption test — For acid obtained from the substance 1 it was found to be . = 119-8 For acid obtained from the substance 2 it was found to be ...... . =114-6 After the aqueous soap-solution had been freed from the substances unsaponifiable in aqueous solution of caustic soda, dilute sul- phuric acid was added until an acid reaction was obtained, when the fatty acids separated upon the surface as a white layer; this was skimmed off and repeatedly washed with warm water until the water no longer gave a deposit with BaOlj. A brown flocky substance de- posited in the mixture of acids and was filtered off in a hot-water funnel; it was soluble in caustic soda solution. The iodine-absorption of the mixture of acids was found to be = 103-7. . For the purpose of isolating the solid acids of the mixture, it was subjected to fractional distillation under diminished pressure. A ther- mometer was inserted in the distilling flask, and a capillary tube led to the bottom in order that a current of dry carbonic acid might be introduced with a view to preventing percussive ebullition. With the same end in view, several loose capillary tubes were placed in the flask, and the whole heated on a graphite bath. The distilling flask was in air-tight connection with a receiver, which again was connected with a suction pump and a mercurial manometer. During the first part of the distillation the temperature rose uninterruptedly to 280° (80 mm. pressure). That which passed over during this time was essentially water with a little acid that spurted over. Between the temperatures 280° and 305° a white, slightly yellowish, acid of crystalline appearance distilled over (distillate 1). That which passed over at temperatures above 805° was of a somewhat more yellow colour (distillate 2). The residue in the distilling flask had now become rather thick and of a dark brown colour. The melting-point, which in the case of the acid mixture before the distillation was found to be 32°, was now found to be Of the distillate 1 =36° 2 =31" The iodine-absorption was found to be Of distillate 1 . . =59-1 „ 2 . . =69-1 Of the residue in the flask . = 95-1 Upon redistillation, the melting-point of distillate 1 rose to 88°, while the iodine-absorp- tion was somewhat lowered. The acid value was found to be 270, while that of the mixture before distillation was 236. After recrystallisation from alcohol the iodine-absorption fell to 22-4, and the melting- point rose to 55° ; the acid value was now 203. If, then, we suppose that the ' stearin ' is a mixture of glycerides of saturated and unsatu- rated acids, the former having an iodine-absorp- tion of 142-6, the percentage of the latter in cod-liver oil might be calculated when it is remembered that the ' stearin,' the iodine- absorption of which was found to be 118-4, con- stitutes about 10 per cent, of cod-liver oil. The percentage of glycerides of unsaturated acids in the ' stearin ' = ^^^, about 80 per cent. The percentage of glycerides of saturated acids in the ' stearin ' will, therefore, amount to 20 per cent., and as, at most, -nrtli of the oil is ' stearin,' the amount of glycerides of the satu- rated acids (palmitic and stearic acids) from which cod-liver oil is supposed to be freed by the freezing process, at 7° of cold, can at the outside be only 2 per cent., probably much less, as will be explained hereafter. XCll HEYERDAHL: NEW CHEMICAL EESEAROHES The ExisTEa^CE of Hydeoxy-acids in Cod- liver Oil. Benedikt and Ulzer ' have devised a method for determining the percentage of hydroxy-acids contained in fats by acetylating their fatty acids. Those of the acids which contain no hydroxyl-group are not affected by the acetyl- ation ; the difference between the amount of potassium hydrate necessary for saponification and that required for neutralising the acetyl- ated fatty acids will be in direct proportion to the amount of hydroxy-acids which they con- tain. If a non-acetylated fatty acid contains X hydroxyls the quantity of potassium hydrate necessary for saponification after acetylation will be X times as large as the quantity required for neutralisation. True, in case the nature of the fatty acid in question be unknown, it will be impossible to determine the percentage of hydroxy-acids, but valuable points may be gained for isolating and identifying the fats. The process in its details is as follows : — One hundred grammes of oil are boiled in a flask with inverted condenser, together with 70 grammes of potassium hydrate dissolved in 50 com. of water and 150 c.cm. of strong spirit until thoroughly saponified, whereupon the whole contents of the flask are poured into a large porcelain basin, a litre of water is added, and sufficient dilute sulphuric acid until acid re- action. The mixture is then boiled until the fatty acids rise to the surface in' the form of a perfectly clear layer, and the alcohol is evajjo- rated. The fatty acid layer is now boiled twice with water, separated, dried in hot-air bath at 30°, and filtered through a dry filter. Fifty grammes of the fatty acids thus obtained are now boiled with 40 grammes of acetic anhydride for two hours in a flask with inverted condenser, and then poured into a deep beaker-glass ; 600 c.cm. of hot water are added, and the whole boiled. In order to pre- vent percussive ebullition a weak current of car- ' Zeitschr. f. ch. Industrie, 1887, p. 149. bonic acid is conducted through a capillary tube to the bottom of the glass. After boiling for some time the water is poured off, and the acetyl- ated fatty acids, being again boiled three times with 500 c.cm. of water, now no longer colour litmus paper red, a sign that all acetic acid has evaporated. The acetylated fatty acids separated from the water are dried in a hot-air bath at 30°, and filtered through a dry filter. For the determination of their acid-value 4 to 5 grammes of the acetylated acids thus obtained are dissolved in spirit, which must be free from fusel oil and acid, and, after the addition of phenol-phthaleine as indicator, titrated with half normal solution of potassium hydrate. About 1"5 gramme of the acids were used for the determination of the saponification- value. Besides the half-normal solutions of potassium hydrate and hydrochloric acid an alcoholic solution of caustic potash is now required. This is prepared by dissolving about 30 grammes of potassium hydrate, previously washed with alcohol in as little water as pos- sible, diluting with alcohol, free from fusel oil, to one litre. The solution is set aside for two days and filtered. As the solution undergQ.es changes on standing, only a quantity sufficient for immediate use is prepared. The acetylated acids are now weighed out in a flask of 100 c.cm. capacity, and exactly 25 c.cm. of the alcoholic solution of caustic potash are added from a pipette. The mouth of the flask is covered with a funnel, and the contents subjected to gentle boiling on a water-bath for fifteen minutes, phenol-phthaleine added, and the excess of alkali retitrated with hydrochloric acid. The strength of the caustic potash solution is determined in a similar way by heating 25 c.cm. of it over a water-bath for fifteen minutes, adding phenol-phthaleine, and titrating with hydrochloric acid. Taking the difference be- . tween this titration and the first, the amount of potassium hydrate used in saponification may be easily calculated, and from this result the saponification value determined. HEYEEDAHL: NEW CHEMICAL RESEARCHES XCIU By this method the percentage of hydroxy- acids in cod-liver oil was examined, but they proved to possess qualities differing from those of other fatty acids examined by Benedikt and Ulzer, and which had to be. taken into account in the determination of the acid- and saponi- fication-value. Thus, in the determination of acid-value it was not sufficient to simply dissolve the acetyl- ated acids in alcohol, as stated before, and then titrate with KOH, because not only did it dis- place the hydrogen in the carboxyl-group, but split off some of the acetyls at the same time. To prevent the latter, it became necessary to • dilute the solution so much that the solution of potassium hydrate became too weak to affect the acetyls. By dissolving the acetylated acids in 150 c.cm. of alcohol, agreeing results were obtained, and the reaction set in instantly with- out splitting off any acetyls. In the determination of the saponification- value a difficulty was encountered by the solution of the acetylated acids assuming such a dark brown colour as to totally obscure that of phenol-phthaleine ; therefore, the change from alkaline to acid reaction could not be observed. Other indicators which were tried, such as rosolic acid, alkanet, gallei'n, phenacetolin, and congo-paper, proved equally worthless. By diluting with ^ litre of water it became possible to distinguish the colour changes and obtain serviceable results. Still, even after these improvements in the process had been made, the percentage of hydroxy-acids was found to be very irregular. Some of the results are stated here : — Acetylated acids from 1. Cod-liver oil free from stearin 2. Cod-liver oil free from stearin 3. Cod-liver oil con- taining stearin . 4. Stearin . Acid-value Si 1 «s» :l}' 170-8 Saponification-' value 203-2 20'7-9 197-2 , 202-8 200' 201 177-7 175-5 207-7 .7 1 200-9 1-176-6 Acetyl- Talue 88-5 36-9 25-1 2-2 From these figures it will be seen that very different acetyl-values have been found for two acetylated acids produced from the same oil, and even that the acid-values of the same acetylated acid do not agree. This irregularity is still more striking in the saponification- values which show, for acids prepared from the same oil a variation of from 197"2 to 207"9 — a difference of 10-7. On account of these irregularities, notwith- standing the greatest care taken in all the operations and in spite of the high iodine- absorption which would seem to point to a scarcity of hydroxy-acids, the presence of a dis- turbing element was apparent, and the agency of the air was suspected. This supposition was confirmed in the most satisfactory manner by excluding the air and replacing it by hydrogen. Numerous experi- ments proved the necessity of this replacement of air by hydrogen, or some other inert gas, not only during the saponification of the oil and the preparation of the free fatty acids, but also during the whole of the analytical operations, acetylation, washing, filtering, and even during the determination of acid- and saponification- value. The results now obtained varied considerably from those given above, and were of eminent interest : — Acetylated acids from Aoid-value Kaponificatiou- value Acetyl- value 1. Cod-liver oil free from stearin . 2. Cod-liver oil free from stearin . 3. Stearin . 191-7 191-8 !,„,.„ 191-91^^^^ X96-3 \ . „„.„ 196-21^^^^ 193-8 193-9 \,ciq.o 193-7 / ^^'^ " 2-1 2-0 1-0 By way of comparison the acids of linseed oil were acetylated in air and in hydrogen, but it was found that air did not affect the acids in regard to their percentage of hydroxy-acids. This was rather unexpected — on account of their high iodine-absorption. Thus it is a unique peculiarity of cod-liver oil that it oxidises with such extreme ease upon XCIV HEYERDAHL: NEW CHEMICAL EBSEAECHES being heated in air, and this property of giving greatly differing acetyl-values upon parallel acetylation in hydrogen and air, may be used as a specific test for cod-liver oil. As the oil proved so exceedingly sensitive when heated in air, it must be supposed as a matter of course, that it oxidised in the process of preparation, during which the air had free access both whilst the livers were being heated by steam and afterwards, and that its percentage of hydroxy-acids, corresponding to the acetyl-valiie 2*0 as demonstrated above, was due to this cause. If an inert gas replaced the air during the process of preparation the oil would in all probability be free from hydroxy- acids, and the acetyl-value would be found to be = 0. This supposition was fully confirmed by practical experiment. For cod-liver oil prepared in a current of car- bonic acid the following results were obtained : — Acid-value Saponification-value Acetyl-value 1. 191-5 191-5 0-0 2. 194-6 194-7 0-1 The analysis was, of course, carried out under the precautions enumerated above. It is probably due to a difference in the percentage of stearin that the acid and saponification values in one case are a trifle lower than those in the other. During the acetylating experiment it was again observed, as before during the determina- tion of free fatty acids, that the oil assumed a darker colour, and acquired a rancid taste and odour. On the other hand, when heated in inert gases it remained almost unchanged. The rcmeiMty of the oil is therefore caused by the formation ofhydroxy-aads^ a/nd mat by its splitting up into free acids. Of course, the iodine-absorption must be in inverse ratio to the proportion of hydroxy-acids in the oil ; and as this determination is much easier and quicker than that of acetyl-value, it might with advantage be applied in cases where the same percentage of stearin in different oils to be examined has been insured. Some of the analyses carried out with this point in view are here placed together for com- parison : — Acetylated : pro- tected from oxlda- tiou Acetylated: not protected from oxidation Frcrm the Oil Acid-value . Saponifieation-yalue Acetyl-value Iodine-absorption 191-8 193-8 2-0 167-7 From the Stearin Acid-value . Saponification-value Acetyl-value Iodine-absorption 196-3 197-3 1-0 116-7 169-3 207-8 88-5 105-6 174-4 176-6 2-2 103-2 Prom- these figures it will be seen what an extraordinary influence the percentage of hydroxy-acids has upon the iodine-absorption ; while the difference between the acetyl-values of the oxidised and non-oxidised oils is 36"5, the difference in iodine-absorption is 52-1. Thus, given the percentage of stearin, the percentage of hydroxy-acids (i.e. the degree of rancidity) of the oil may be pretty accurately determined by the iodine-absorption. As the percentages of both stearin and hydroxy-acids tend to diminish the iodine- absorption, the chemical expression for the best oil in the estimation of the trade must be the highest possible iodine-absorption. It will now be understood that the 2 per cent, of saturated acids found by the examina- tion of stearin, or the greater part at least, were hydroxy-acids formed from unsaturated acids by the action of the air during the pro- gress of analysis. Bromine Absorption To 200 grammes of cod-liver oil, from which the solid fats (' stearin ') had been separated by cooling in a freezing-mixture and filtering through cotjion-cloth, were added 140 grammes of potassium hydrate dissolved in 100 c.cm. of HEYBRDAHL: NEW CHEMICAL RESBAROHJlS xcv water and 300 c.cm. of alcohol. The whole was heated in a current of hydrogen until thoroughly saponified, then diluted with 1^ litre of warm water, and dilute sulphuric acid added until an acid reaction was obtained. The mixture was boiled until the fatty acids separated in the form of a clear floating layer, the water poured ofi", and the fatty acids further washed three times in boiling water, all the time in a current of hydrogen. The water poured ofi" the acids was filtered : in this way 178 grammes of fatty acids were obtained, part of which, solid at ordinary temperatures, was isolated in a suction-filter. One hundred grammes of the fluid acids were dissolved in 300 c.cm. of pure glacial acetic acid, cooled in a freezing- mixture, and 38 c.cm. of bromine added, drop by drop, during constant stirring. The solid bromine-com- pounds thus produced were separated fi-om the liquid and dried on tiles. After being washed with spirits, 20 grammes of these bromine products were repeatedly boiled with alcohol of 96 per cent. ; the liquid was drawn ofi" and the insoluble part dried, first between filtering- paper and then in vacuo over concentrated sulphuric acid. In this manner a white solid substance was obtained, which was almost insoluble in alcohol, ether, chloroform, benzene, and glacial acetic acid. After renewed repeated boiling in alcohol its percentage of bromine, when determined by igniting it with pure quick- lime, was found to be constant. Two bromine-determinations gave : 1. 70'80 per cent, bromine 2. 7101 The ultimate analysis of the bromine product gave : C H li 22-40 per cent. 3-00 per cent. 2. 22-60 „ 2-99 „ Calculated from the formula CjjH^gBrgOj : 22-59 per cent. C, 2-88 per cent. H, and 70-95 per cent. Br. This corresponds to the figures obtained. The bromine in the compound OijHjgBrgOj may have entered either by addition, or by substitution, or by both. If the bromine entered iuto the compound, entirely or partly, by substitution, a molecule HBr would be formed for every hydrogen-atom substituted in the acid by bromine. We can, therefore, ascertain how much bromine is present by substitution in the compound Ci^HggBrgOj when we determine the quantity of HBr formed during the process of bromation. For this purpose 10 grammies of the fluid acids were dissolved in chloroform, and to the solution, cooled in a freezing-mixture, 3*6 c.cm. of bromine were added, drop by drop, during continual stirring. The bromine compound was separated by filtration and the filtrate agitated with 600 c.cm. water, separating the rest of bromine-compound which was filtered, oS". The chloroform being separated from the water was again agitated with 100 c.cm. of water and the two watery extracts united, filtered, and precipitated by silver-nitrate; 0'04 grm. of silver bromide was thus obtained corresponding to 0'02 grm. hydrobromic acid. Suppose, now, that one, only, atom of hydrogen had been substituted by bromine in Cj jH^gBrgO^, then no less than 3 grammes HBr would have been formed from the 10 grammes of the original acid instead of the 0-02 gramme actually found. Consequently all bromine atoms WMst ha/ve entered the compound CijHjgBrgOj by addition, and the original acid must have been an unsaturated fatty acid of the formula CijHagO^. From experiments made so far, this remark- able acid seems to be present to the extent of about 20 per cent. ; on account of its peculiar properties and structure, coupled with the large percentage in which it is present, it probably plays an important, perhaps the most important, part in the therapeutical action of cod-liver oil and therefore I propose to give it the name of ' therwpic add.' Its saturated bromine combina- tion would then be octo-bromo-therapic acid, or octo-bromo-margaric acid, if we look upon it as a saturated acid. XCVl HETERDAHL: NEW CHEMICAL RESEARCHES The Oxidation of the Patty Acids of Cod- liver Oil by Potassium Peemanganate K. Hazura has propounded the following rule for unsaturated acids : ' Unsaturated fatty acids in alkaline solution add, when oxidised by potassium permanganate, as many hydroxyl- groups as there are free valencies in the acids, and form saturated hydroxy-acids, with the same number of carbon-atoms in the molecule.' The acids of the oil or fat are isolated and oxidised in alkaline solution by potassium permanganate, the composition of the hydroxy-acids produced is determined, and from their percentage of carbon and number of hydroxyl groups a con- clusion is drawn of the carbon percentage, and number of free valencies in the original un- saturated acids. The fluid fatty acids of cod-liver oil were oxidised according to this method ; 30 grammes of these acids, prepared from oil free from stearin and separated from the solid acids in a suction- filter, at ordinary temperature, were saponified by 36 c.cm. of caustic potash solution, specific gravity 1-27. The soap was dissolved in 2 litres of water, and 2 litres of a 1^-per-cent. solution of potassium permanganate were slowly added during constant stirring. After being set aside for ten minutes the oxidation was cut short by reduction with an aqueous solution of sulphurous acid, which was added until all unchanged potassium permanganate was reduced to hydrated manganese peroxide, and this again dissolved. About 2 grammes of a white solid substance, insoluble in cold water, were formed and filtered off through cotton-cloth. This yield being so insignificant the natural con- clusion was that the bulk of hydroxy-acids would be found in the aqueous solution ; the solution was then filtered anew in order to free it from every trace of insoluble acids, and KOH added until a slight alkaline reaction was obtained. The liquid was then evaporated to a volume of 300 c.cm. and, after being cooled, sulphuric acid was added, to acid reaction. The precipitated manganese peroxide was exactly reduced by sulphurous acid, after which the liquid was distilled in a current of steam in order to get rid of volatile acids, possibly present. The residue ought now to contain the non-volatile hydroxy-acids soluble in water. The brown-coloured liquid was concentrated by evaporation, cooled, and agitated with ether, which, however, did not extract anything. NagCOj was then added until alkaline reaction, the liquid boiled, and the manganese precipitate produced was removed by filtration ; the filtrate, evaporated to dryness on a water-bath, was extracted with alcohol of 80 per cent, by boiling in a flask with inverted condenser. In this way a brown syrupy fluid was obtained, but no hydroxy-acids. The result of these investigations' was, then, that only a couple of grammes of solid, in water insoluble, hydroxy-acids were obtainable from 50 grammes of original acids. The natural inference was, therefore, that the oxidation had struck deeper than intended, and that the method as described above was useless for the preparation of hydroxy-acids from the acids of cod-liver oil. After several unsuccessful attempts to gain the desired end, it was at last found that the oxidation had to be proceeded with at a tem- perature of 0°, and by a stronger solution of potassium permanganate. Half-saturated solu- tion of KMnO^ gave good results. Thus, the acid which yields the hydroxy-acid described below has the property of being very sensitive to oxidation at ordinary temperatures, but can at a low temperature bear a powerful oxidation without being split up. The white, in cold water insoluble, oxidation product was filtered off through cotton -cloth, repeatedly washed with cold water, dried on tiles, and then extracted with cold ether. After the ether had been distilled off, the mixture of hydroxy-acids (m.p. 110°) was treated with boiling water, in which it was partly soluble. But as the soluble part had its m.p. at 180°, and the insoluble at nearly 200°, and as besides, both turned brown on being heated to the melting point — which was not the case with the HETERDAHL: NEW CHEMICAL EESEAROHES xcvu original mixture — it was apparent that the two bodies were decomposition products. It was to be apprehended that heating with aqueous ether or alcohol might also split up the hydroxy-acids ; they were, therefore, now re- crystallised from chloroform after being dried on tiles. After many recrystallisations a pro- duct was obtained with melting point between 114° and 116°. The ultimate analysis of this hydroxy-acid gave the following result : — C H Found Oalcnlated for C,,H„04 68-77 69-09 11-34 11-50 The molecular weight was determined from the acid value. , About 2-5 grammes hydroxy- acid were dissolved in 100 c.cm. of alcohol (free from acid) and titrated with ^n. solution of potassium hydrate in excess. The excess was retitrated with -^n. HCl. 1. 2-3397 grms. / hydroxy-aoid \ 170-8 \ 2. 2-7598 grms. L gave acid- value J 171-3 J Calculated for 169-7 The molecular weight calculated from these figures. 1. 2. 327- 826' -8 1 -9 J Calculated for C„H„0. 330-0 The percentage of hydroxyls in the hydroxy- acid was determined by the acetylation method; 8 grms. of acid were boiled for two hours with 40 grms. acetic anhydride in a flask with inverted condenser. The acetyl acid thus produced was freed from acetic acid by boiling four times with ^ litre water. After separating it from water, acid-value and saponification-value were determined. 4-541 grms. acetylated acid were dissolved in 150 c.cm. acid-free alcohol and titrated with |-n. solution of potassium hydrate. Acid- value was found to be Calculated for O.A.O. (0,H.O). 134-8 135-2 1-327 grms acetylated acid were saponified on a water-bath with alcoholic solution of caustic potash for fifteen minutes. The excess was retitrated with |n. HCl. Calculated for Saponifioation-value waa found =411-9 405-8 The number of hydroxyl groups is calculated from the acid- value and saponification-value: — 134-8: 411-9 = 1: 305 It will be seen from this equation that the hydroxy-acid contains two hydroxyl groups, and therefore has the formula Gy^BL^fi.^(0]S.)^. From the acid-value of the acetylated acid, 134-8, the molecular weight may be calculated. Molecular weight Found 416-5 Calculated for 0..H..O.(0A0), 414-0 The silver salt of the hydroxy-acid was pre- pared in the following manner : — The hydroxy-acid was heated upon a water- bath with ammonia until it was thoroughly saponified and the excess of the latter evapo- rated. Silver nitrate was added in excess to the hot soap solution. The precipitate was first washed with cold and then with warm water until the water no longer gave reaction on silver. The precipitate was heated with ether, in a flask with inverted condenser, upon a water-bath several times until the separated ether on evaporation left no residue. After drying to constant weight, its percentage of silver was determined : — Calculated for C„H„AgO, 1. 0-4120 grm. silver salt gave 0-1021 grm. Ag = 24-78 per cent. 24-68 2. 0-4154 grm. silver salt gave 0-1027 grm. Ag = 24-72 per cent. All the results obtained as above agree well with the corresponding figures for the hydroxy-acid, OijHgjO^. This formula for the hydroxy-acid under consideration is therefore scarcely questionable, and it is beyond doubt that it was prepared by oxidation from a cor- responding unsaturated acid of the fluid acids of the oil, by two hydroxyls entering its double bond. I propose for this unsaturated acid the name ofjecoleic acid, derived from its origin; the f XCVlll HBYBRDAHL: NEW CHEMICAL EESEARCHBS corresponding hydroxy-acid would then have to be designated as di-hydrosy-jecoleic aoid.' As demonstrated above, the yield of hydroxy- acidsis exceedingly small so long as the oxidation is performed at temperatures above 0°; it is there- fore probable that the acids are split up at higher temperatures ; even the hydroxy-acids break up on boiling with water. This peculiar property of the acids appears to be closely connected with the therapeutical properties of cod-liver oil. The Saturated Acids of Cod-liver Oil By the saponification of cod-liver oil, from which the fats that are solid at low temperatures had been removed, and by the following decom- position of the soap, a mixture of acids was obtained, from which, as already mentioned, a substance solid at ordinary temperatures separated. After repeated recrystallisations from alcohol a white solid acid crystallised in glancing plates, with constant m.p. 62°. The acid-value was determined : — Calculated for C„H3,0, 1. 2-4638 grins, aoid gave aoid- value =217*2 \ oio.o 2. 2-1189 grms. „ „ =217-1/ The molecular weight calculated from these figures : — I- ■ ■ 267-8U5g.o 2. . . 2579 J The silver salt was prepared in exactly the same manner as that of hydroxy-jecoleic acid (p. xcvii). The percentage of silver was found to be : — Calculated for 0„H„AgO^ 1. 0-3599 grm. silver salt gave 0-1063 grm. Ag^ = 29-53 per cent. [ 2. 0-3366 grm. silver salt gave 0-0998 grm. Ag | ^^'^^ — 29-65 per oent. ) V. Hiibl's iodine-absorption method was applied, for ascertaining whether it were a saturated acid or not. ' How far jecoleio aoid is identical to doeglic aoid, which has the same percentage compositiou, cannot yet be decided. They are probably isomers. 0-3966 grm. acid was dissolved in 18 com. of chloroform and 25 c.cm. of v. Hiibl's iodine solution were added. After a lapse of two hours the fluid was titrated with sodium-thio- sulphate in the ordinary way; 43-43 c.cm. were required. 25 c.cm. of iodine solution + 18 c.cm. of chloroform required likewise 43-43 c.cm. of sodium thiosulphate ; consequently the iodine absorption was = 0, and the acid was therefore a saturated fatty acid, and evidently pakniUc acid. Percentage of the Acids found in Cod-liver Oil It cannot yet be conclusively stated in what proportions the acids discussed above are present in the oil. There are probably more, hitherto unknown, acids which have not as yet been determined, and these researches were not made with a view to quantitative determination. How- ever, some conclusions may be drawn from them and from iodine-absorption determinations. The mixture of acids prepared from oil free from stearin contains — 4 per oent. palmitic acid, or less 20 „ therapic acid, and, 20 „ jecoleic acid, at least. The remaining moiety consists, in all like- lihood, of one or more lower unsaturated acids with one double bond, or perhaps a mixture of such an acid and jecoleic acid. The author hopes at some not very dista.nt day to be. enabled to give further particulars on this subject and of continued researches on the acids discussed above and on cod-liver oil generally. Researches on Ptomaines in Cod-liver Oil Raw medicinal oil was examined according to the method of A. Gautier and L. Mourgues.' The oil which was employed for this purpose was that which rises, first of all, to the surface from the livers set aside for putrefaction ; con- ' Les alcalcndes de I'huile defoie de morue. HEYBRDAHL: NEW CHEMICAL RESEARCHES XCIX sequently, raw medicinal cod-liver oil of the lightest colour met with in trade. One hundred kilos, of this oil were agitated, with the same volume of spirits of 33 per cent., in which 4 grammes of oxalic acid were dis- solved in every litre. The emulsion produced was set aside and the spirit when separated poured off. Milk of lime was added to the spirit until only a slightly acid reaction re- mained. The greater part of the oxalic acid and some inevitably accompanying fat-particles were precipitated as oxalic and aliphatic calcium salts, and were removed by filtration. The liquid was then distilled under diminished pressure upon a water-bath at temperatures varying from 35° to 55°, with some capillary tubes in the distilling flask to prevent percussive ebullition. In this way the liquid was evapo- rated to -^th of its original volume. The concentrated liquid was digested with freshly- precipitated calcium carbonate until neutralisa- tion. The precipitated calcium oxalate was removed by filtration, and a few drops of lime- water, until alkaline reaction, added to the filtrate, which was then distilled to dryness at 50°, under diminished pressure. The residue was dissolved in spirit (90 per cent.), filtered and redistilled under diminished pressure ; mixed with a small quantity of water, solid potassium hydrate added, and the whole agitated with ether. To the ethereal solution oxalic acid was added, and to the exceedingly insignificant precipitate, two or three drops of water and some potassium hydrate were again added, when a few milligrammes of an intensely strong smelling oil separated on the surface. The quantity was too small for any closer examination. This result proves that ptomaines have not had time to form, and in the raw oil, therefore, are present only to an extremely trifling and insignificant extent. This agrees with the results of Gautier's and Mourgues' experiments. f 2 CONCLUDING REMARKS It is generally admitted that the therapeu- tical action of cod-liver oil is one entirely its own ; the peculiar benefits derived from its employment in nervous, rheumatic, scrofulous, phthisical, and other diseases are not to be ob- tained from any other remedy whatsoever. It is therefore by no means wonderful that the scientific mind has been occupied ever since the early days of organic analysis in attempts at discovering the exact nature of the con- stituents which give cod-liver oil its special value. A synopsis of the more important of these researches is given in the preceding pages by Mr. Heyerdahl, together with a full account of his own investigations. These are drawn up in the style that is supposed to be orthodox for scientific communications, the bare facts being recorded, and the reader left to digest them as best he can. The writer may therefore be permitted to add this supplement in which the facts will be presented in a somewhat more predigested. form, and some of their theoretical and practical consequences will be pointed out. The first chemical research on cod-liver oil was by Wdrzer, and dates as far back as 1822. This investigator seems to have come across the the ptomames which Gautier and Mouegues discovered sixty-six years later, but he had not our present means of determining them. Spaaeman (1828) found that the oil contained 97 per cent, of the glycerides of mwrgcvrio, oleic, and delfkimc — now called valerianic — acids, besides 3 per cent, of colouring and odorous substances. Marder (1830) discovered that the oil contained chlorides and sulphates ; iodine was discovered by Hopfer de l'Orme (1836); to this bromivs was added by Her- BERGER and phosphorus by DE Vrij (1838). A most elaborate qualitative and quantitative analysis was made by de Jongh in the year 1843. He found that the oil contained gaduin, certain hilia/ry constituents, and six peculiar compounds, all of which later researches have proved to be decomposition products formed during the analysis, and not pre-existent in the oil. He also stated that acetic and butyric acids were present, but the existence of these bodies is not fully confirmed by his analysis. Lastly, and in conformity with earlier analyses, he found the rest of the oil to be composed of margarin and olein. These organic substances found by de Jongh comprised in all nearly 99^ per cent, of the oil, and it is a little surprising that not a single one of them really exists in the oil. The remaining half per cent, were inorganic salts, all well known from earlier examinations. De Jongh made quantitative determinations of them, but his results unfortunately were not particularly accurate. For instance, he found over 100 times more iodine than the oil actually contains. Of course it should be remembered that the analysis of organic compounds was then in its infancy, and the methods he employed were very faulty. He, however, gave his analysis the appearance of great exactitude (up to third and fifth decimals), and this for a very long time secured for his researches the reputation of a standard work. EETEOSPEOT ci WiNCKLEH (1853) found that the fatty acids were not combined with glycerin as glycerides, hut with propyloxide ; a statement which has not been corroborated by any of the later investi- gators, and which certainly is a mistake. Down to 1869 the fatty acids of cod-liver oil were supposed to be margaric and oleic acids, when ScHAPER found the former to be palimtie acid, with a small percentage of stearic acid. Stanford (1884) showed that iodine was present in a much smaller amount than had previously been supposed : he found the average percentage to be 0-000322. Buchheim (1884) proved that cod-liver oil does not and cannot contain any biliary acids. Allen and Thomson (1885) found that cod-liver oil contained cholesterin. Salkow- SKY (1887) pointed out that the well-known reac- tion with sulphuric acid is not due to the presence of bile-substances, as hitherto supposed, but to the simultaneous presence in the oil of chole- sterin, fatty acids, and colouring matter (' lipo- chrome '). This particular pigment is found in cod-liver oil and palm oil, and a trace of it in cotton-seed oil, but in no other oil. Gautiee and MouEGUES (1888) found several alkaloids in the darker oils, but not in those of a lighter colour. , We can now sum up the results of the analyses made up to 1888 by giving the follow- ing list of the constituents said by the various investigators to be present in cod-liver oil : — ' Sufel. Jcnum. 1837, p. 115; Brandes' Arch. vol. xxxii. p. 90 ; Ph. Cmtralbl. 1830, p. 17. ^ De Jongh, Disguisitio Com^arativa Chemico-medica de Tribus Olei Jecoris AselU Speciebtis, 1843. ' A. Gautier et L. Mourgnes, Les Alcakfides de I'Huile de Foie de Morue. * Beneditt, Analyse d. Fette, 1892, p. 369. ' Jahresb. d. Chemie, 1856, p. 490. » Oeiger's Magazin, 1828, p. 302. ' Hufel. Journ. 1836, p. 115. ' Ann. d. Ph. u. Chemie, xxxi. p. 94. " Pharm. Centralhalle, xxx. p. 261. " Zeitachr. f. anal. Chemie, 1887. " Pharm. Centralhalle, xxx. pp. 10, 261. " Wigger's Bufem. Jahresb. d. Pharm. 1869, p. 340. " Arch. A. Pharm. cxxvi. (1858), p. 185. " Pharm. Centralhalle, xxviii. p. 628. Palmitin (fig. 877, p. 235) Stearin (fig. 878, p. 235) . Olein (fig. 879, p. 236) . Hydrochloric acid ' . Phosphoric aoid^ Sulphuric acid ' Pormio acid ' . Acetic acid ' . , . Butyric acid ^ . Valeric acid ' . Capric acid * . . . Pellioacid''(p. 367) Cholic acid ^ „ . Bilifellioacid^. Gadinic acid * . Physetoleio acid * (p. 191) Morrhuic acid* Delphinic acid« (fig. 672, p. 176) Iodine' .... Bromine*. Potassium' Sodium ' . Calcium ' . Magnesium' . Iron" .... Manganese' Gaduin ^ . Bilifulvin >= (p. 436) . Biliverdin^ „ Lecithin » (fig. 1,536, p. 435) Cholesterin '» (p. 90) Phytosterin '" „ . Gelatin ' (p. 436) . Albumin" (p. 432) . Ammonia" Propyl-oxide " . Trimethylamine " (fig. 1,121, p, Butylamine ' (p. 440) Iso-amylamine ' (p. 441) . Hexylamine ' „ Dihydrolutidine ' „ Asseline ' i. • Morrhuine ' „ Green soft resinous matter ' Brown hard resinous matter ' Peculiar comp. sol. in alcohol ^ Peculiar comp. insol. in alcohol ' Four other peculiar compounds '' Lipochromes " (p. 436) . Other, colouring matter ' , Smelling substances ' . , 815) Per cent. 26 - 19 72 - 76 •/ 100 100 According to these analyses the bulk of the oil (95-98 per cent.) consists of olein and the body, first described as margarin, afterwards corrected to palmitin and stearin. The exist- en CONCLUDING EEMAEKS ence of these acids, however, had never been properly determined by any exhaustive analysis ; in fact, they had simply been permitted to pass down like heirlooms from generation to genera- tion, and their identity had never been chal- lenged. This is to be explained by the fact that there were no proper methods for isolating those fats : the constituents of which belong to the higher homologues of the aliphatic acids. For the determination of these it is indispensable that -they should be in perfect purity, free from any admixture of higher or lower homologues, isomers, or acids with other bindings. Such, then, was the state of things when Heyerdahl commenced his investigations, which have occupied him uninterruptedly since 1880. The difficulties he has had to overcome have been formidable, for, at first, no systematic methods were available — only some isolated tests like Hehner's value, acid value, ' and bromine absorption were known, and these alone were not of much utility for the purpose. Since then, however, several others have been devised, such as saponification value (1883), iodine absorption (1885), and acetyl value ' (1887). These, with their many ingenious applications, complementing and connecting the earlier methods, have established a system of analyses by which much valuable information may be gained. But although these tests give excellent results for saturated acids, and are serviceable in respect to the oleic series, some of them turned out to be quite inapplicable in their original form to the acids of cod-liver oil, and a great deal of experimenting had to be gone through before modifications fit for use could be found. The results of Heyerdahl's researches may now be briefly recapitulated. He could not find any olei'n or stearin in the oil, but he discovered two new glycerides, one of which, therapin (fig. 884, p. 237), is exceedingly interesting, and has already been described. The other and hitherto unknown glyceride is ' The operation of these analytical tests is explained in the chemical part of this book, p. 241. jeool&in, containing jecolei'c acid (fig. 752, p. 193, and fig. 880, p. 236). This, like thera- pic acid, is an unsaturated acid, but with only one double bond. It belongs to the same series as oleic acid, and is probably isomeric to doeglic acid. It is a very unstable compound — much more so than any of the other members of the same series. Heyerdahl succeeded in preparing the less unstable hydroxy-acid, which, however, breaks up in boiling water. He computes the amount of therapin to be 20 per cent, of the oil, and of jecolein, at least 20 per cent., but probably more. The rest of the glycerides he believes to consist of one or more unsaturated acids, belonging to the same series as jecolein, but hitherto unknown to chemists. The only saturated acid that he could find was pahnitic add, and it was present to the extent of probably less than 4 per cent. More- over, even this small percentage, actually found, was not detected in the ' stearin ' at all, but in that part of the oil which remains fluid at a temperature of 7° of cold (centigrade). This is another interesting result of his researches : that the so-called ' stearin ' — i.e. the fats of the oil that solidify at lower temperatures — con- tains neither palmitin nor stearin, but glycerides of, probably, new unsaturated acids — ^not yet determined. From this we may see that through the excusably ignorant demands of the trade, constituents of probably great therapeutical value are removed from the oil and literally thrown away. Rancidity of Ood-liv&r OiZ.— This is shown by Heyerdahl's researches to be founded, not upon free acids produced by the breaking up of the glycerides, but upon the formation of hydroxy-acids. There are free acids, to a slight extent, present in the oil when it is still in the liver of the living fish. Indeed, at that stage there is even more of the free acids present than there is in the steam-prepared oil, because some of these bodies are volatile and evaporate during the process of preparation. By exposing the liver to temperatures below EANCIDITY cm freezing point the cellular tissues burst, pro- bably because, under the influence of cold, they contract more than the oil. The oil then exudes, and in this way can be produced with- out the application of any heat, though not in commercial quantities. Heyerdahl found such oil to have an acid-value of 1'3, and of course there was no suspicion of it being rancid. By subjecting other exactly similar livers to the steam process he found that the oil produced at the beginning of the operation had an acid-value of 0-76-0-99 ; but at the end of the process this had diminished to 0-58-0-81, showing that some of the volatile acids had evaporated. In this oil also there was no rancid taste or smell. Further heating decreased the amount of free acids still more, but only to a slight extent; afterwards the acid-value began to rise slowly. After heating on a water-bath for five hours and a half, and at the same time passing 207 litres of air through the oil, the acid-value rose, although only to 1-22 ; but now the oil smelt and tasted disgustingly rancid. From this we may gather, that the free acids can ha/ve nothing to do with rancidity, other- wise the acid-value would be proportionate to the rancidity. The formation of hydroxy-acids is the true cause of the rancidity of cod-liver oil, and it is more disposed to the formation of these acids than any other known oil. The dif- ference in this respect between different oils and fats is, however, only one of degree. Olive oil, for instance, always contains hydroxy-acids, but they do not give rise to effects so unpleasant as those of cod-liver oil with the same acetyl- value. In fact, olive oils with — according to Heyerdahl's determinations^ — acetyl-values of 10-6-16*4 were very fair specimens of their kind, and when used for salad dressing were quite satisfactory. It is hardly necessary to add that cod-liver oil with similar acetyl-values would be very decidedly objectionable. Castor oil is a good instance of what hydroxy-acids are capable of ; it is not, to put the matter mildly, a popular article of consumption, as indeed is pretty well proved by the fact that its chief patrons are those unfortunates who are still sub ferula. This failure to suit the popular taste is due to castor oil being by nature the glyceride of a hydroxy-acid, ricinoleic acid. Its acetyl- value is as high as 153'4, even when the oil is in its purest state, and, of course, higher when it becomes rancid — or, strictly speaking, more rancid — by the addition of further hydroxyls. It would seem that the more double bonds a fatty acid contains, the more easily do the hydroxyls attach themselves to it. Thus, cod- liver oil, which contains therapic acid with four double bonds, the highest number known, is very apt to become rancid. This aptitude, naturally, increases proportionally to the temperature, and although when well corked and kept in a cool place we have found the oil to keep in good condition for two years, it will, on the other hand, if left uncorked in a warm place, be entirely spoilt in less than a week. The practical conclusions that we are entitled to draw from the foregoing are of very con- siderable importance to all who are in any way interested in the administration of cod- liver-oil. The real value of thi remedy lies in the fatty aaids which it contains in the form of glyeerides, and obviously the great point is to preserve these adds absolutely unchanged. If they are altered the special advantages of the oil are thereby lost ; and that is by no means all, for the hydroxy-acids which are formed from these peculiar fatty acids are not only of no value, but are actually injurious ; for they- make the oil nauseating to the taste and, what; is far worse, they are very apt to set up gastrin disturbances — of all things the least desirable in the majority of the cases for which cod-liver oil is prescribed. It is no easy matter to preserve these acids unchanged, even when the best methods for doing so are adopted. They are, unfortunately, most unstable in constitution. Indeed, in the whole materia medica it would be difficult to find another body with a constitution so delicate as that of therapic acid, the most valuable con- CIV CONCLUDING REMARKS stituent of cod-liver oil. It cannot even exist in the isolated state, and its little peculiarities in this way are perhaps hardly to be wondered at when we consider that its formation takes place in animals whose temperature never exceeds 5° C. A compound with similar con- stitution and properties could never be formed in warm-blooded animals or, in short, anywhere except where it is formed ; and therefore it is hopeless to look for something to take its place. Nothing amongst all the other organic com- pounds, whether prepared by nature or in our laboratories, can possibly supplant the fatty acids of cod-liver oil. Preparations of God-liver Oil. — The phar- maceutical preparations which have been made of cod-liver oil are remarkable both for their number and for a curious similarity in their liie-history. That, in the case of most of them, is now complete, and it has been, briefly, an introduction with a great flourish of trumpets, a period of popularity, and — a niche in the museum of the curiosities of pharmacy. A selection descriptive of them will be found in an earlier part of this work. Here they may be dismissed with ' de moriuis nil nisi honwm,' but concerning the preparations that have not yet 'joined the majority ' a word or two may be added. Emulsions. — Amongst them the genus emul- sion with its numerous varieties stands at present first. The therapeutical justification for emulsi- fying cod-liver oil is said to be that a minute subdivision aids its absorption into the system. Some people, of course, might be inclined to ask if there is any proof that such aid is required — ^if the physiological emulsification of the oil by the intestine has ever been found deficient ; also, supposing it has, can the deficiency be remedied by means of artificial emulsions ? These emulsions are so difierent from nature's own that the best artificial sub- division of the oil results in globules which, compared with those seen in the intestinal epithelium, are like, say, Jupiter and his fifth satellite. Now, as the diflSculty of subdividing fatty bodies may be said to increase in geo- metrical ratio to the fineness of the division, it requires some stretch of imag^ination to com- prehend the advantages of an artificial emulsion which stops so far short of what nature requires. Again the fact remains that even the most ' elegant ' emulsion will, after a time, break up, and separate the oil, and when it reaches a patient in this condition, a new but very dif- ferent emulsion must be produced by following the well-known instructions, ' Shake the bottle.' This, however, is but one aspect of the question — the mechanical; the physiological and chemi- cal yet remain. It is more than probable that any emulsion in passing through the stomach will be destroyed, as an emulsion, by the hydrochloric acid of the gastric juice before it can reach the duodenum. Further, supposing emulsions were merely useless, they might, cceterispanbus, be forgiven. But, unfortunately, the emulsification of an oil means accelerating the hydroxylation of the fatty acids, and for this reason: the subdivision of it enormously increases the contact surface by which oxygen can enter, and consequently increases the facility of forming hydroxyls : these are the bodies which cause disturbance of the digestive pro- cesses and the well-known and much dreaded cod-liver oil eructation. Of course the rancid taste of these oxidised fatty acids can easily be covered in an emulsion, but this tricks the palate only, not the stomach; here fine flavourings are of no use, for there are no nerves of taste, but there are nerves of equal sensibility, though acting in another way. They do not appreciate hydroxyls, and when hydroxyls are forced upon them there is trouble, the evidences of which are nausea, loathsome eructations, and so forth. Thus there seems to be but one conclusion to the question : even if all the advantages were proved up to the hilt, this one oljection, the. inevitable oxidation of the fatty acids, would in itself be quite suflBcient to condemn all attempts at emulsifying cod-liver oil. While, theoretically, the simple mechanical subdivision of the oil does not seem quite the PREPARATIONS AND EMULSIONS cv thing required, its insnflSciency is being prac- tically proved by that great but slow teacher of man, experience. The result is a further ' advance ' : the addition of an adjuvant to the emulsion. Needless to say, the adjuvant is de- signed to help out the hypothetical difficulty in the absorptioa of the oil; another beautiful instance of how an idea, if once generally ac- cepted, is handed down, heir-loom-like, from generation to generation, and never questioned. As a type of these adjuvants we may take ' pan- creatin.' Here, again, the critical person would be disposed to ask, Is there any proof that the absorbability of cod-liver oil has been affected by a deficient pancreatic secretion, and if there is, can it be remedied by this ' pancreatin ' ? Of the four carefully set forth active elements of pancreatic juice, three of them, trypsin, amy lop- sin, and rennet have, as a matter of fact, no action whatever upon fats. The fourth is the yet rather hypothetical ferment, steapsin ; and even if the existence of this in the pancreatic juice is granted, there still remains the reason- able question — is it present in the dried juice ; and, should the answer be in the negative, then where does the use of.' pancreatin' come in ? But should it be in the affirmative, it raises the further question — what does steapsin do ? On the showing of its own advocates its action must result in splitting off the therapic acid, the existence of which as a free fatty _acid in an emulsion is simply impossible. It would, in accordance with the conditions present, either break up altogether or undergo conversion into the thing evil — an hydroxy-acid. Finally, the vehicles necessary for preparing artificial emulsions axe not always therapeutically expe- dient ; they are quite unnecessary, and there- fore undesirable additions to our materia med/ica. All these considerations lead us to one con- clusion — ^that there is no really valid reason for the existence of a/rUficial emulsions, but that there seem to be obvious reasons for their non- existence. Other considerations tend to the conviction that there is no need of artificial aid of any sort, because nature is capable of undertaking the work herself, and does so, to perfection in the ^physiological emulsions she pre- pares ; the elements necessary for the natural, that is the perfect, emulsification being provided by nature, exactly where and when they are re- quired, and in a quantity which, so far at least as cod-liver oil is concerned, is apparently always amply sufficient. These elements may be classified roughly as the mechanical and the chemical actions. Concerning the former no more need now be said than that, compared with the pestle and mortar, 'it grinds exceedingly small,' but concerning the latter, some further explanation may not be out of place. It is a most interesting fact, as bearing on the medicinal virtues of cod-liver oil, that it differs from all the other fats with which we are acquainted in respect to the ease with which it can be emulsified in the presence of the two chemical bodies fresh pancreatic juice and glycerin, without the aid of any gum whatever. Nature provides the former, and we may re- iterate that there is no real evidence regarding an insufficiency in her supply; the latter can never be insufficient, because it is provided by the oil itself, in which it is present in the precise quantity required. The secretion of the pan- creas comes in contact with the oil, not in the stomach, where the acid fermentation would render its action futile or perhaps, indeed, totally destroy it, but in the duodenum, from which downwards through the jejunum and ileum all the conditions are in its favour. Under these circumstances, the fresh pancreatic secretion by its action upon the oil provides the other neces- sary element, the glycerin. Nature herself seems to enforce the lesson, if we would let her, that by means of the pan- creatic juice she provides, and the glycerin of the oil, such an emulsion is produced in the human economy as it is hopeless to look for outside, however skilful our manipulations. After all, the most astonishing circumstance connected with artificial emulsions is, that so much labour and thought should have been cvi CONCLUDING EEMARKS bestowed upon overcoming a hypothetical diffi- culty of assimilating the oil, when all the while no one was believing in the therapeutical value of these very same fats, and therefore not attaching the least importance to them. The valuable part of the oil was always considered something distinctly separate from its fatty constituents, and learned men and grave pro- fessors have occupied themselves with hunt- ing after this 'something,' only to find it, like a phantom, suddenly disappearing before their eyes just when they thought they had grasped it. This will-o'-the-wisp is the so- called ' active principle,' and on account of the extensive use made of this catch-word we cannot dismiss the subject with a mere passing notice. Active Principles. — The efiect of cod-liver oil on the system is so different from that of any other oil, that science has subjected it to all sorts of torture in order to make it reveal its secret. This the poor oil was, of course, quite willing to do had it been properly asked. The inquiries, however, were always wrongly directed. From 95 to 98 per cent, of the oil was supposed to be ordinary fat, and quite un- worthy of any special attention. The whole of the examination and cross-examination was therefore turned upon the remaining two to five per cent. It is astonishing what a number of things were found in this small quantity, as may be seen in the lengthy list on p. ci, all of them being ' chaperoned ' by scientific men of distinction. It is difficult to imagine that any of them could have an important influence upon the action of the oil, for those that are, with- out doubt, present are so in homcEopathic doses only; the percentage of some, indeed, cannot find expression before the third or fourth decimal. Yet nearly every one of them has in turn been represented by its discoverer, or someone else, as ' the active principle ' of the oil, and has served as the basis for substitutes intended to do away with cod-liver oil entirely. Volumes have been written on this, scientists have lectured upon it, enterprising pharmacists have prepared it, sold it, and presumably profited by it, and yet it does not exist ; the oil, however, still exists, and in a fairly flourish- ing condition, while its proposed substitutes are either resting in the aforesaid ' niche,' or seem likely to do so at an early date. Such a result is not surprising if it can be demonstrated that this two to five per cent, of odds and ends has nothing whatever to do with the therapeutical value of cod-liver oil ; and we think that some further considerations will lead to the conclusion that such is the case. By far the greater number of the remedies used in medicine act by the physical or chemical influence which they bring to bear upon the tissues of the body. Cod-liver oil, on the other hand, is one of a much smaller group of materia medico,, which act, not by influencing the tissues, but by becoming part and parcel of them ; in other words, they are simply food substances, which, in one way or other, possess special advantages distinguishing them from other and ordinary foods, and justifying their adoption as therapeutical agents. No active principles are to be expected in the members of this group, and to attempt to find some such body in cod-liver oil is just as likely to be succesful as would be an endeavour to find an active principle in — say bread. It is indeed, at first sight, surprising that anyone should have thought that cod-liver oil could contain an active principle, but for this, as for most things, there is a reason. The abstract idea of what should be the properties of a medicinal substance is naturally derived from the properties common to the great bulk of such substances, and as most medicines act in the way we have described, it is obviously quite possible for them to possess ' active prin- ciples ' ; indeed, as a matter of fact, the majority of them do. But although the majority of drugs have an active principle, it is logically ridiculous to deduce that every drug must have such a principle ; yet this is exactly what is done by many people, and, combined with the ingrained misconception of the nature of the fatty con- ACTIVE PRINCIPLES evil stituents, is the explanation of the absurd belief in, and the unavailing search for, an active principle in cod-liver oil. We have said that the search was unavailing, but that is, perhaps, hardly the correct way to put it, for whenever a search has been instituted it has been successful, only each different investi- gator has happened to find a different ' active principle.' This is rather unfortunate, for of course the latest discovery is the real active principle — until such time as another one is found. Like the men who discover them, the fame of these valuable principles is somewhat transient — here to-day and gone to-morrow ; yet one thing always remains — cod-liver oil. For centuries this oil has been used and esteemed by all the nations able to obtain it. Many of them had no communication with each other: the inhabitants of North America did not learn the virtues of cod-liver oil from the inhabitants of Northern Europe, or vice versd, but the various peoples in each of those regions learned, the lesson from their own individual experience. God-liver oil, it is to be noted, was not the only, or even the most easily obtainable, oil or food, and yet every one of these primitive peoples selected it, and it only, being taught by experience that it was quite different from, and much more valuable than, other oils or food substances. Here, then, we have the process of ' natural selection ' by which cod-liver oil was separated from, and esteemed above, other and similar products ; and this was done, not in one region only, or by one people only, but in several different and widely separated regions, and by different and altogether disconnected peoples. As we have said, the oil could not have been originally the one thing, or even the most likely thing, ' in the running ' ; but when we find that from its rivals it, and it alone, was selected, and this in places so far from each other as Norway and North America, and by nations so different as the Laplanders and the Alaskan Esquimaux, we are forced to come to the con- clusion that there must be something special in the oil — something not to be found in other substances^but this something is not an ' active principle.' If there really were an active principle in cod-liver oil, we might be pretty sure that it would have been discovered long ere now. In the case of other medicinal substances, the active principle : alkaloid, glucoside, acid, or any- thing else, has been discovered and separated; its chemical composition has been determined, and its physiological action has been investi- gated and settled, and there the matter has ended. In no case has another and different active principle been found to explain the value of the drug ; in no case has an active principle totally disappeared from the ken of man after it has been discovered, investigated, and established ; in no case, in fact, do these things happen — except in the case of cod-liver oil, where they all happen; and the active prin- ciple of to-day is the knell of tJie active principle of yesterday. We are, in consequence, forced to the conclusion either that the active principle of the oil is something different in every way from all other active principles, or, what is more likely, that no active principle exists. Heyerdahl has been the first to direct his inquiries to the fatty constituents, and their reply to his attentions has been prompt and to the point. His researches are important in respect to their practical results and of great interest in regard to the theoretical conclusions that may be drawn from them concerning the active principle of cod-liver oil. The idea that this principle is to be discovered somewhere outside the glycerides may be safely discarded. When it is remembered that the chief property of cod- liver oil is to build up, and strengthen, the system it appears almost ridiculous to look to infinitesimal fractions of well-known compounds for the explanation of that building-up property. These fractions are not even perfectly inno- cent in their nature. For example ; Gautier and Mourgues, found in the light-brown oil minute quantities of some two or three alkaloid-like poisonous compounds, over which no little CVlll CONCLUDING EEMARKS fuss was made, as they, also, posed in the character of the latest ' active principle.' They have been classified by their discoverers as ' leucomaines,' that is to say, as products of katabolism, formed during life and through the ' vital forces ' that sustain life and in casu va. the livers of the living fish. This must surely be a mistake ; if it were true, there could be no reason why these alkaloids should not be found in all sorts of cod- liver oil. But according to the investigators themselves the bodies in question do not occur in the steam- prepared oil, and it is only in the light-brown oil that they are present in a quantity (0'2 per mille) sufiBcient for chemical examination ; while, again, they are altogether absent in the brown oil. Heyerdahl found them just traceable in the pale oil as detailed by him in the preceding pages. The following are facts on which all agree, and in the opinion of the writer they are very striking. In the oil extracted from fresh livers there are no alkaloids ; in the oil drawn from decayed but still comparatively fresh livers there are traces of them ; in the oil skimmed off whilst the putrefaction is in full swing they are plentiful; in fact, the greatest quantity occurs ; in the brown oil, which has been ex- posed to a temperature of 120° to 150° C, there are none ; all of which seem to point to these alkaloids being really ptomaines formed by bac- teria from putrefying albuminous substances of the liver. In the case of steam-prepared oil the bacteria have no opportunity of commencing their work on account of the relatively high temperature at which the oil is prepared, and also, because the exuding oil forms a protective covering all over the hepatic tissue. But no sooner is the oil drawn off than the bacteria commence action upon the unprotected liver- rests, as is quickly evidenced by a stench which, even vdthin an hour if the tempera- ture happens to be favourable, may become so strong as to be almost intolerable. In the case of pale oil when the livers are heaped in a barrel, only those that come to the surface are attacked, the rest being protected by the exuding oil. Gradually, however, as this is drawn off, more and more of the livers become exposed to the air, and when the pro- cess has proceeded so far that the light-brown oil is being formed the bacterial activity be- comes very lively, as manifested by the same intolerable smell. Finally, at the temperature at which brown oil is made, these bacterial products are decomposed or volatilised, and therefore they are not found in this particular variety. The 'liver-rests' (Graxe) consist for the most part of albuminous substances, and when not under the protecting cover of the oil the rapidity with which they are attacked by bacteria is simply astounding, and it is very difficult to prevent, or put a stop to, the bacterial destruction. We have tried sulphurous acid and carbon-disulphide,but for practical purposes they were useless ; and carbolic acid, sublimate, and similar disinfectants cannot be used, as the liver-rests are employed as manure. Curious misunderstandings have arisen from an ignorance of this property of the hepatic tissue : its extreme susceptibility to bac- terial influence. Thus a paper was lately read before TAcad^mie des Sciences, Paris, in which theauthor states that the alkaloids of cod-liver oil are all of biliary origin, and goes so far as to assure us that this can easily be proved by the following proceeding! After a small slice of fresh liver tissue has been snipped off and care- fully disinfected, it is left for two or three hours under a desiccating bell jar, after which plenty of microscopical crystals of alkaloids are to be found. This is the process of stopping the chinks and leaving the door wide open — of course, after those two or three hours under the bell jar it would be surprising if abundance of ptomaines were not found. These alkaloids, therefore, cannot be con- sidered as normal products in the light- brown oil, but are undoubtedly impurities with which the oil has been contaminated by the putrefac- ACTIVE PRINCIPLES cix tion of the liver. They are powerful poisons, and have, of course, a therapeutical eifect upon the system ; but — not the wonderful building-up and strengthening action which is the character- istic of cod-liver oil, and which the varieties of the oil without ptomaines manifest at least as well — and need we add quite as safely? — as those varieties that do contain such ' adjuvants.' Now, however, when we have Heyerdahl's discoveries before us there is no need to search for some mysterious ' active principle ' amongst the 5 per cent, of odds and ends. These, to be concise, are not normal constituents of pure cod-liver oil, inasmuch as valeric, capric, and gadinic acids, gaduin, ammonia, tri- methylamine, alkaloids, and such substances are partly decomposition-products, formed in the hands of the analyst whilst conducting his operations, and partly products of bac- terial activity after the oil has left the hepatic cells. They exist only in one special kind of oil, in the preparation of which opportunity for bacterial putrefaction has been given. Cod-liver oil is really much more a food substance than a medicinal substance, and to expect it to contain an ' active principle ' in the true sense of the term is little less than ab- surd; its therapeutic value depends, certainly not on any active principles, but on its remark- able efficiency as a nutritive agent. It is, then, much more rational to look to the newly discovered acids, which constitute 95 per cent. of the oil, as being the probable basis of its therapeutic value. The chief function of the absorbed fats in the economy of the organism is to form com- pounds from which the system can, in the most effective way, be supplied with the necessary income to cover its expenditure. Of such compounds, forming a store from which the organism is incessantly drawing supplies of repairing materials and which in themselves provide all the necessary elements — phosphorus, nitrogen, carbon, hydrogen, and oxygen — of these we Jcnow only two, protagon and lecithin. When more fat is absorbed than is necessary for forming these two compounds it is deposited as fat, and in the adipose tissue, without any intervening link. Protagon and lecithin are analogous com- pounds ; the structure of the former, which is largely found in the brain, is very complex and not fully known. This much, however, has been ascertained, that it can be split up into two compounds, cerehrin and kerasin, probably glucosides, and that lecithin is a constituent of both. The structure of lecithin, on the other hand, is fully known (vide fig. 1,536, p. 435). It is composed of phosphoric acid to which a nitrogen compound, choline, is linked on one side, and a glyceride on the other. Further, it has been found that the glyceride is not always the same : sometimes it consists of two similar acid radicals, sometimes the two are quite different, evidently dejpending upon the kind of fat that was at hand at the ti/me of formation. Lecithin originates in plants, and from them it enters the animal organism, where it is found in every growing cell. As lecithin is practically ubiquitous in foods it arrives in the stomach in company with nearly everything we eat, and even with cod- liver oil. It is not affected by the gastric juice, but when it reaches the intestines it shares the fate of cod-liver oil ; the pancreatic juice, or rather the hypothetical steapsin, splits it up into its constituents, glycero-phosphoric acid, free fatty acids, and choline. All these bodies pass through the striated surface of the epi- thelial cells, and are then taken up by the lymph-corpuscles — cod-liver oil, it is to be noted, is taken up just in the same manner, A regeneration of the lecithin takes place within the lymph-cells, which then discharge it into the lacteals. When fats and lecithin are taken simul- taneously in the food, as they almost always are, they meet in a disintegrated state in the lymph-corpuscles, that is, as free fatty acids of various kinds, corresponding to the fats partaken of, and as glycero-phosphoric acid, glycerin, and choline, or perhaps a derivative of ex CONCLUDING EEMARKS the latter.^ Then the regeneration of lecithin is commenced in the lymph-corpuscles, and there can be no doubt that glycero-phosphoric acid makes a selection from the fatty acids now within its reach, and without any regard to the connections of its former existence. If it picks out those acids which are best fitted for its new duties, that is only what we would expect it to do, in harmony with all the genetic laws within our knowledge — for instance, the selecting acti- vity of secreting cells. Its new duties are to give off to the blood the material that is re- quired for the maintenance and renewal of the body. For this purpose it is embodied with the protoplasm of the cell, and when the blood arrives there, its oxyhsemoglobin gives off its oxygen by which an actual breathing process of the protoplasm is maintained, resulting in the breaking-up of lecithin and other of its constituents into various compounds, which are carried away with the blood and de- posited at the places where they are properly required. Now, unless the above, which is founded on the latest physiological data, is utterly wrong, the extraordinary facility with which therapic, jecoleic, and perhaps other acids of cod-liver oil break up under the influence of oxygen makes it obvious that they are, collectively, the very thing required for the easy nutrition of the body. By them the work of building up and strengthening the system can be accom- plished with the least expense of energy, and it seems almost impossible that the lecithin should select any other acids than these for its regeneration. This simple and pliiin theory may be ex- pressed in few words — the active principle of cod-liver oil is the oil itself. Recapitulation. — ^The reputation of cod-liver oil was established many centuries ago and, indeed, probably in prehistoric times. It was ' Glycero-phosphoric acid, and recently aJso neurine, a derivative from choline, have been found in the blood, both in the free state {Ber. d. d. chem. Oesellschaft, xxvii. Bef. 420). no reputation built up by adventitious aids ; no perfectly disinterested scientist discovered the virtues of the oil, and forthwith adver- tised them — for the benefit of suffering hu- manity. The oil, in fact, made its own repu- tation, or to put the matter somewhat more accurately, it was discovered, advertised, intro- duced, and established in favour by ' natural selection,' and it is notable that this took place, not in one country only, or amongst one people, but in several widely separated regions of the globe and amongst several totally disconnected races. The reputation of cod-liver oil was thus ' made and guaranteed ' by nature herself, and as civilisation opened the means of intercourse between different countries, the use of the oil spread from the regions of its origin, till at the present day it has become practi- cally universal. Here a very natural question may crop up : if cod-liver oil is so excellent, why all the attempts that have been made to aid its action by adding this thing or that to it, or by making it into something different from what it is ? A study of the history of these attempts supplies an answer, for they can all of them be traced back to one and the same starting-point — an endeavour to overcome the difficulties in administering the oil. These difficulties were really serious, as anyone with experience, especially personal experience, of the matter will admit. The oil, as hitherto known, possesses sometimes a far from pleasant taste, always a tendency to disorder the diges- tion and to cause the much dreaded repeating. It was with the praiseworthy object of over- coming these drawbacks that the 'prepara- tions ' of cod-livej" oil were started, but un- fortunately in directions that were not in the least likely to lead to success. The drawbacks are due to certain impurities which are, or, as we ought now to say, were, found in the oil. Now, even from the a priori point of view, there does not seem to be much chance of success with these preparations by merely covering the impurities, no matter how skilful the pharmacy employed. In fact, there RECAPITULATION CXI is only one way to success in the administra- tion of the oil, and that is, not by disguising but by exclvMng the impurities ; and we use the word ' excluding ' advisedly, because once the presence of the impurities is permitted, removal is impossible ; it follows, therefore, that an in- ferior cod-liver oil cannot he refined, and to speak of steam refined oil shows a complete ignorance of the subject. The impurities are of two kinds. First, the decomposition products of albu- men which are derived from the putrefaction of the liver tissues, and which naturally give the oil a most repulsive taste and smell. Secondly, the objectionable products from the oil itself formed by the oxidation of the free fatty acids, which are the cause of the nauseous repeating. The first step towards the exclusion of these impurities was the invention and introduction of Peter Moller's ' steam process.' The oil pre- pared by this is absolutely free from decomposed albumens, if the process is properly carried out. It does, however, contain, more or less, the oxidised fatty acids, and therefore even the very best steam-prepared oil is apt to cause repeating. The second great step towards the production of a pure oil has now been accom- plished. The results of our chemical investiga- tions show that the fats of cod-liver oil are entirely difierent from other fats, and that one of their most remarkable characteristics is a much stronger tendency to form hydroxylated compounds than that possessed by any other fatty substances. Our knowledge of these chemical and physiological properties, acquired through Heyerdahl's interesting researches, forms the foundation of our new process, based upon the principle oi prevention. It was found that the only practical method by which the hydroxylation of the free fatty acids could be prevented was by their complete isolation from the action of free oxygen throughout the whole process of preparing the oil. This is done in the process which we have devised by keeping the oil under an atmosphere of carbonic acid from beginning to end — from the moment when it leaves the liver cells till it is safely bottled and corked. Hydroxylation is thus impossible, and the oil is not only odourless and tasteless but it is absohdely hyd/ivtioylrfree, and therefore does not cause unpleasant repeating. It is, in short, the ideal cod-liver oil, for it contains the maximum of the therapeutically valuable constituents and the minimum, or more precisely none, of the objectionable constituents. This, of course, is only when the oil is fresh, for in time the fatty acids must become oxidised, no matter how well they may be protected, and it is for this reason that we insist on the importance of never using any oil older than that of the previous year's fishery. These remarks may be concluded by a short statement of the conditions that we would lay down as essential for the preparation and administration of medicinal cod-liver oil. First, the livers should be those of cod-fish only, and those from any other source rigidly ex- cluded. Secondly, the livers should be perfectly fresh, and any that have been kept, or that betray the slightest sign of decomposition, should be rejected. Thirdly, livers showing any indication of disease or derived from diseased fish should on no account be used. Fourthly, in extracting the oil the livers should not be ex- posed to a high temperature, and to the proper temperature for just the necessary time only. Fifthly, from the beginning of the process of extraction till it is safely corked up in bottles, the oil should never, even for a moment, be permitted to come in contact with the atmo- sphere or with free oxygen in any form. And lastly, a good oil should never be mixed with other drugs beforehand. It may be done invmediately before being taken, but it is far better, when their employment is con- sidered necessary, to give them separately. II THE LAW OF ATOMIC LINKING DIAGEAMMATICALLY ILLUSTRATED BY P. PECKBL MOLLBE, Ph.D. CONTENTS PAGE CHEMISTRY 1 HYDEOCAKBONS : Formation and Specification: Single Bonds, Paraffins i , . 7 Formation : Double Bonds .... 19 Triple Bonds 22 Cyclo-compounds 24 Specification : Open Chains, Double Bonds, Ethylenes 35 Triple Bonds, Acetylenes 39 Closed Chains, Cyclo-hydrocarbons 42 OXYGEN-COMPOUNDS : Alcohols 67 Phenols 91 Ethers 118 Aldehydes 130 Ketones 138 Ca/fhohydflrates 151 Qlucosides 160 Acids .... . 165 COMBINATIONS OF OXYGEN-COMPOUNDS: Cyclo-acids 208 Aldehyde-acids 227 Kbtone-acids 227 Compound Ethers 9S1 Ether-acids 250^ acib-anhydiiides 256- cxvi COl^TENTS FAQE OXYGEN-CYCLO-COMPOUNDS 259 HALOGEN-COMPOUNDS : Derivatives feom Hydbocakbons 265 ., „ Alcohols and Phenols 269 ,< „ Aldehydes 271 „ „ Acids 273 SULPHUE-OOMPOUNDS 275 Derivatives from Dyad Sulphur 280 „ „ Pbtead Sulphur 286 „ „ Hexad Sulphur 289 NITROGEN-COMPOUNDS : Nitrogen- and Oxygen-compounds 301 Nitrogen- and Hydrogen-compounds 312 Ammonia's Combinations with 1. Hydrocarbons : a. Primary (Amido-) Bases 313, 341 6. Secondary (Imido-) Bases 314, 352 c. Tertiary (Nitrile-) Bases 315, 353 d. Qiiarternary (Ammonium-) Bases 316,354 e. Di-amines . . 317, 356 /. Poly-amines 317, 360 g. Acridines 340 h. Naphthyl-amines 350 2. Hyd/roxyl, Hydroxyl-amines 318 3. Alcohols, Hydramines 321 4. Phenols, Amido-phenols 321, 346 5. Naphthols, Amido-naphthols 351 6. Aldehydes, Aldehyde-ammonias 322, 368 7. Acids: a. Ammonimn-salts 323 6. Amido-acids 324, 3G3 c. Amides and Acid Amides 327, 308 d. Amidines 331 e. Anilides 341 8. Am,monia : a. Hydrazines and Hydrazo-compotmds 332, 380 b. Azo-oxy-compomids 834 c. Azo-compomids 334 d. Mixed Azo-oompoimds 836 e. Diazo-oompounds 836 /. Hydrazones 888 g. Osazones 338 h. Azines 340 CONTENTS cxvii NiTROGEN-CYCLO-COMPOUNDS PAGE Pentagons 380, 391 Hexagons 388 Pyridine-derivativeB 391 Qtiinolme- derivatives 404 Morpholine-derivatives 416 Cyanogen and Derivatives 419 PEOTEIDS 431 PTOMAINES AND LEUCOMAINES 440 TOXINS AND ANTITOXINS 441 FERMENTS ^^^ ATOMS: Physical Atoms ^^^ Chemical Atoms 453 Limkage 454 Stereo-cheTmstry 45J Valencies 484 ABBEEYIATIONS American Chemical Joii/mal Ameii can Jowm al of Pharm acy Ann alen der Chemie vmd Pharmacie Ardh iv der Tharmacie Axch iv fU/r expe rimentelle 'PaXhol ogie wnd PTuvt makologie Beilste m, Hcundhuch der orgamisehen Chemie, 2" Aufl. 1886-1890 Benedikt, Analyse der Fette 2" Aufl. 1892 "Bexidhte der deutschen ohermschen Gesellschaft BerH«er klm tacfee Woohensolirifli hoiling voint British Vharmaeopceia, 1885 Centralblaii iur Bacteriolo gte imd Farasitenkiinde Chemical 'Sews Chermker ZeiUmg Chemist & Dr uggist Compte* rendiis des seances de VacadeTn/ie des sciences Deutsche Meiizinische Wochenschrift HaUibiirton, Chemical Physiology and Pathology, 1891 Heger, Synopsis der neuen Arzneinvittel, 1891 JoumaZ der rxms ischen chemischen Gesellschaft Jommalfiir praktische Chemie Sowrnal of the Chendcal Society Lauder Brnnton , Introduction to Modern Thera- peutics, 1892 Mei ical Awau al Meii cal Maga zine melting yoint Merck's Bei ichte Meyer , Jehih uch der Chemie Monatahe fte fii/r Chemie Monatshe/ c > because it makes no difference so long as it is the same carbon-atom on which the different arrange- ments take place. It is the succession of the several carbon-atoms that is essential to the chemical character of the compound, and the succession is not altered in the above arrangements ; it is only a bend which the chain makes round its intermediate carbon atom. Of course the individual links, as regards the kind and number of their appendices, must remain unaltered. For our purpose .at present the rule holds good everywhere ; generally our representations will be a straight chain, but in order the better to understand some processes it will be advantageous to make exceptions. Sometimes, dependent upon the character of the aflSxes to the carbon's valencies, such exceptions will prove to alter the physical properties of a compound, but we need not consider that here, as it will be fully gone through when we have to discuss atoms in space (p. 453). OPEN CHAINS; PARAFFINS, NORMAL 9 Propane (OgHg) is a liquid below —17°, otherwise a gas. Again, when we take a molecule of methane and one of propane (O3H3), the new compound, and repeat the process Pig. 20 Fig. 21 to 6 o -it- T - t t t ) o 6 0*0 One molecule of methane and one of propane = one molecule of butane, C4H10, and one of hydrogen, Hj we then have another compound, butane (O^Hjq), a gas that condenses to a liquid at + 1°. We will once more take a molecule of methane and a molecule of the last compound, butane, and again remove two atoms of hydrogen. Fig. 22 Fig.. 23 O O O 9 6 o- o o o One molecule of methane and one of butane one molecule of pentane, C5H12, and one of hydrogen, Hj The' new compound called pentane (G^TEL^^) is a liquid at ordinary temperature, boiling at 37-39°, possessing an ethereal smell. Like all the foregoing compounds it is found in petroleum. In the same way we can go on adding a molecule of methane to every new compound produced, removing at the same time a molecule of hydrogen. For obvious reasons an abbreviated illustration of such heaping methane upon methane is a matter of necessity. In the figure below the arrangement will be understood without further explanation, except that ' x ' and ' y ' stand for any figure, including ' 0.' As most of the fats have derivatives of the parafiins as constituents, some of them must be named: (x + y= 2) OgHit a fluid. (x + y= 3) G^Hie (x + y= 4) OsHis „ (x + y= 5) OsHjo (x + y= 6) CiflHjj „ (x + y= 7) CiiH^ (x + y= 8) CijHjs „ tetradecane (x + y = 10) Oi^Hj^ „ hedeoane (x + y = 12) CigHj^ „ heptadecane (x + y = 13) C17H35 „ octadecane (x + y = 14) CuHjg „ eicosane (x -i- y = 16) OjoH^j does not boil without decomp. docosane (x + y = 18) OjjHij „ „ „ „ tetracosane (x + y = 20) G^^^ „ „ „ „ pentacosaiie (x + y = 21) O25H53 not yet prepared Normal hexane heptane octane nonane decane undecane dodecane ■B. p. 68°-5 „ 98° „ 124° „ 149°-5 „ 173° „ 194°-5 „ 214°-5 „ 252°-5 „ 287° „ 303° „ 317° M. p 18° 22° 5 )} 28° 36" 7 11 44° 51° 4 10 HYDEOOARBONS, OPEN CHAIN The highest hydrocarbon actually known is pentatriacontane (GgjH,^), but derivatives from a hydrocarbon as high as Og^H,go are met with (theobromic acid, p. 178). The nomenclature of these hydrocarbons from pentane is very simple and easy, being formed from the Greek ciphers. It must be striking to anyone looking at the above figures how much they are like a chain con- sisting of a number of links of FiQ. 25 9 OH, = Fig. 26 9 flanked at each end by a link of CH3 = The theory by which organic chemistry has lately made such gigantic strides has therefore been named the law of the linking of atoms, and chain is quite an accepted word to designate the disposition of atoms in a molecule. RADICALS It will be noticed in the above examples that each compound may be looked upon as a joining of two kinds of links, one a methane from which one hydrogen-atom has been cut off (fig. 26), and the other either a methane from which two such atoms have been removed (fig. 25), or a chain with one hydrogen-atom removed (fig. 22). We will find as we go on that all compounds may be con- sidered a joining of two other compounds, from each of which some part has been cut off, leaving one or more free valencies through which the rests of the compounds unite. Such rests are termed radicals (or synonymously radicles, groups, residues, rests). There are a great number of such remains of a molecule which we again and again meet with in different compounds, and which may be split off and, as it were, transplanted from one compound to another. On account of their frequent occurrence it has been found convenient to provide them with special names, as a rule systematically formed, though lack of agreement among chemists has unfortunately sometimes supplied more than one name to the same radical, or the same name to different radicals. Radicals of paraffins may be looked upon as formed by splitting off one or more hydrogen- atoms from the hydrocarbons, and the nomenclature has been formed from the respective paraffin by changing the end syllable 'ane' into 'yl' when one hydrogen-atom has been removed, into ' ylidene ' when two, and into ' enyl ' when three such atoms have been split off. The following, table presents those most frequently used : Radicals formed hy the removal of one hydrogen-atom, leaving one free valency (mono-valent radicals') Fia. 27 9 Fio. 28 Pia. 29 Fio. 30 ? t Fig 31 1 < > ( » ( k 4 1 6 i t < > c 1 Methyl, CH3 Ethyl, C^Hs Propyl, C3H7 Butyl, C^Hs Pentyl or amyl, C5H1 Here the hydrogen-atom has been removed from the end-link: it is indifferent which of the three hydrogen-atoms connected with this last link of the chain be removed, as the valencies are of equal value. If the hydrogen is removed, not from one of the end-links, but from a link inside the chain, the PARAFFINS. RADICALS H radical is prefixed ' iso.' Methane and ethane having no inside link, propane is the first to form an iso-radical : Fio. 32 Fia. 33 G- t Iso-propyl, O3H7 Iso-butyl, C^Hg As mentioned, p. 8, the valencies being of equal value, it does not affect the chemical properties of a compound if the grouping round a carbon-atom is differently arranged,, or, in other words, if the succession of the respective carbon-atoms remains the same ; it is indifferent whether the chain represents a straight horizontal line or makes a bend at some particular point. Thus, instead of representing iso-propyl as above it may also be represented like this : Fig 34 o G — <>— O Iso-propyl, C3H, Though the chemical properties are unaffected by such different grouping the physical properties may, as we have already mentioned, sometimes be affected ; but, as a rule, we may say that it makes no difference. (For further explanation and limitation of this rule see the stereometrical chemistry, p. 460.) Radicals formed hy the removal of two hydrogen-atoms, lea/ving two free valencies (di-valent radicals) : Fia. 35 ' Fig. 36 Fig. 37 + + Hethylidene or methylene, CHg Bthylidene, O2H4 6 Propylidene, CgHe Also here, any two hydrogen-atoms may be removed from the end-link without altering the chemical character of the radical. If two hydrogen-atoms are removed from different but neighbouring carbon-atoms, unsaturated hydrocarbons (p. 19) are formed, but if ihe carbon- atoms are different and not neighbouring, cyclo-compounds (p. 24) are formed. Radicals formed by the removal of three hydrogen-atoms, leaving three free valencies (tri-valent radicals) : The only two to be mentioned here are Fig. 38 ' Fig. 39 O" • ' -+ Methenyl, CH Ethenyl, C^B.3 The others are radicals of unsaturated hydrocarbons, and will be found on p. 33. 12 HTDROCAEBONS, OPEN CHAIN It must be borne in mind that the use of radicals is solely a matter of convenience, and has nothing to do with the question of their actual existence, or non-existence, as isolated independent bodies. HOMOLOGOUS SERIES If we put those hydrocarbons we have just described, in a row, beginning with methane and ending with pentatriacontane' (OjgHjj), abbreviated in the manner shown below for the sake of space Fia. 42 Pig. 40 Methane, CH^ Fid. 41 r r 0>HH-HI — O 6 o T ? ? O O (I FiQ. 44 3 Ethane, CgHj Propane, C3H5 Butane, C4H11, Pentane, O5H1, Hexane, OeHj^, Fig. 46 5 Heptane, C7H1S Fig. 47 6 O— Octane, CjHia Fig. 48 7 Nonane, CgH^, -O &0. Fig. 49 Q we see there is a difference of one methylene = 0H2 between every member of the series and its next, neighbour. We shall hereafter become acquainted with more such series where the difference is OHg between the nearest members : they are termed homologous series, a characteristic of which is that all the members resemble each other closely in their chemical behaviour; their physical properties, however, undergo a gradual change proportionate to the increase in the number of carbon-atoms. Although often the extremities of a series may be widely different, two neighbours will be nearly identical. Thus in the paraffin series the first four numbers are gases, methane having only recently been condensed to a fluid, whilst the fourth member, butane, is condensed by + 1°. The next members up to pentadecane (OijHgj) are fluids at ordinary temperature with steadily rising melting and boiling points. The rest of the paraffins are solid, and boil without decomposition, only under diminished pressure, whilst the melting and boiling points still rise. Shortly, homologous compounds may be described as chains formed in the same fashion, but from different numbers of methyl. ISOMERS It will also have been noticed that all the compounds considered in the paraffin series were produced by substituting methyl for one of the atoms of hydrogen bound to the end-link of the chain. Now, it is indifferent (as already explained when discussing the radicals, p. 10) which of the hydrogen-atoms is replaced so long as it belongs to the same link; and for the sake of uniformity and better comparison we have preferred that the substitution take place on one of the extreme hydrogen-atoms of the chain. But the hydrogens of the end-links are not the only ones that may be replaced; a hydrogen-atom fixed to any of the intermediate links may just as well be displaced by methyl in a similar way. The products ensuing will have much the same chemical properties as PARAFFINS. ISOMERS 13 the regular (normal) componnd, but some of the physical characteristics, such as boiling and melting points, will show a difference. Such compounds are termed isomers. We have described homologous compounds as chains formed in the same fashion but from different numbers of similar links ; so we can say isomers are chains formed from the same number of similar links but in different fashion. * It is evident that no isomers can be formed of any of the three first paraffins ; the links cannot be placed in any other position that would make a difference in their mutual relations .when we bear in mind the above rule about replacements on the same carbon-atom. With hutane the possibility of isomers commences. It will be remembered that the formation of butane (fig. 20, p. 9) is illustrated thus : Fio. 51 One molecule of methane and one of propane 0*0 = one molecule of butane, C^H^q, and one of hydrogen, H^ Methyl has replaced the extreme hydrogen-atom of propane; but if instead of this atom we remove one from the intermediate link, and place our methyl there, .then we shall have a structure of this form ; Fia. 53 Methtl O - m ' Q Methyl 0~-H ► i t "0 Methyi, + 0«S 6 6 MSTHEITTL i^ Isobutane, isopropyl-methane, or trimethyl-methane, CiHu The new compound is a gas, colourless, condensable at a lower temperature by some degrees than butane, which, however, it otherwise closely resembles. When we look upon it from the ' The term ' isomerism ' has been given widely different encompassments. Even if compounds have as little in common as have glyoide alcohol (fig. 491, p. 116), hydroxy-propionic aldehyde (homologous to glyooUic aldehyde, fig. 556, p. 135), propionic acid (fig. 669, p. 176), ethyl formate (fig. 862, p. 281), and methyl-acetate (fig. 863, p. 231), they are quite commonly spoken of as isomers, for the only reason that they happen to have the same empirical formula, CjHjOj. As long as we did not understand upon what their differences were contingent, it might have been of speculative interest to com- prise them in the term isomers, but with our present knowledge the interest is gone like that of a trick when we under- stand 'how it is done.' Others have gone to the other extreme, and distinguished between isomers, metamers, and isometa/mers, divisions and subdivisions, with benefit to scarcely anybody but the printer. 14 HTDEOOAEBONS, OPEN CHAIN central atom of carbon it appears like methane that has a methyl upon three of its four sides ; hence the name of in-methyl-methane. We take the next member of the parafiBn series, pentane, and see what can be done after the same fashion with that. The formation pf pentane was this (fig. 22, p. 9). Pig. 55 Pia. 54 ? ? ? ? 6 ^ i 6 o o — o ? -iy- -o Methane, CH^ Butane, C4H10 = If we put methyl on one of the intermediate links we have Pig. 56 Pentane, C^'S^ Pig. 57 4 ^-44- A A or, if the methyl link to the left exchanges places with the hydrogen-atom on the same carbon-atom, which it can do, according to the rule, p. 8 : Di-methyl-ethyl-methane, pseudo-pentane, C5H12 ; b.p. 10° We can look upon pseudo-pentane as methane which has had two of its atoms of hydrogen substituted by methyls, and the third by ethyl; hence the name. There is still a way, different from this, to arrange the links of carbon-groups. That part of the chain looking like ethyl is composed of Fig. 58 i Methylene Fig. 59 Methyl The latter will be recognised as a methyl-group, and can exchange places with the only atom of hydrogen left in the methane-group (fig. 56). When that is effected we have again a new compound : Pig. 60 a ? 6 O-HH-O Tetra-methyl-methane : a fluid, b.p. 9°-5 ; above that temperature a gas It is so named because, viewed from the central atom of carbon, it may be considered a methane in which all four atoms of hydrogen are substituted by methyl. PARAFFINS. ISOMEES 15 There are only these three different ways of arranging the four carbon-atoms with their atoms of hydrogen, when we remember that it is quite immaterial which of the atoms of hydrogen is removed and replaced by a methyl-group, as long as they belong to the same atom of carbon. We will now give yet another example, and take for that purpose the next member of the paraffin series, hexane. All hydrocarbons may be considered as composed of different numbers of methane from which have been removed atoms of hydrogen in pairs. Ethane is two molecules of methane less two atoms of hydrogen, or, what is the same thing, two methyl-groups. Propane is three molecules of methane less four atoms of hydrogen. Butane is propane and one methane less a pair of hydrogen- atoms ; pencane is propane and two molecules of methane less two pairs of hydrogen-atoms ; and finally hexane is propane with three molecules of methane less three molecules of hydrogen. Fig. 61 Fig. 62 6 6 Propane and three molecules of methane less three pairs of hydrogen atoms ~ O ^►— O G">0 0~0 ©-© one molecule of hexane + three molecules of hydrogen As we have mentioned above there is only one way of arranging the carbon-atoms in propane ; consequently the three carbon-groups must remain in the same position in all the variations we make with hexane. Three methane groups then remain which we can join to propane in any one of the four ways following, all differing from the above and from each other. Of the three methane-groups we can place two at one end-link and the third at the other : Pig. 63 Fig. 64 ,& ♦-0 *-— o' -o Or we can place a methane on each of the three links : Fig. 65 Q O O O Q 'O. 6 6 Iso-hexane , di-methyl-propyl-methane, ethyl-isobutyl, OeHi^ ; b.p. 62° Fig. 66 O O (p o o ^►— o 4 O 6 o Methyl-di-ethyl-methane, O^^t, ; b.p. 64° 16 HYDROCARBONS, OPEN CHAIN Or two molecules of methane may be placed on one of the end-links, and the third on the centre-link. Fig. 67 Fio. 68 . ! . - • - o o

--o G-O Q O-O o Fig. 72 9 4h- O H It will be seen at a glance that this arrangement is identical with that of tri-methyl-ethyl-methane, under No. 4, just above. PARAFFINS. ISOMERS 17 It remains only to make ourselves acquainted with some isomers from the rest of the paraflBns, wMch we shall meet again more or less disguised. From octane : Tia. 73 ? o - • -- o 9 T 9 o o From decane : Di-methyl-pentyl-metliane, CaHu, hypothetical Derivative : m-Xylene-hexa-hydride () Fig. 74 0,. 3 i \ 1 < ) ( » 1 > < I ] > < • ( i ( > ( ► Di-methyl-iso-heptyl-methane, di-iso-amyl, CjoHaa ; b.p. 158° Fio. 75 <• O .,11! ?! ^ ^0 6 6 6 6 i <» Methyl-ethyl-iso-hexyl-methane, CioHa^ Derivatives : Cymene (fig. 142, p. 29) ; Geraniol (fig. 356, p. 74) Fio. 76 hydrogen-^i acceptable; Ha.^ when a chain ,y point where l/ The " " ( o— < ) ( > ( > C ) ( O— ( ) i 4 ) ) V. ) < ) < ) ( 1 ( 1 ( ) Methyl-iso-propyl-pseudo-pentyl-methane, C, qH^j Derivatives : Limonene (fig. 144, p! 29) ; Ehodinol (fig. 358, p. 74) In order to show the gradual formation of the paraffins, we have built up the whole series by continually adding methane to every new compound formed, but of course we can make a short cut by joining two of the higher hydrocarbons. For instance, we have formed pentane by first joining two methanes, then adding successively three other methanes, always deducting two hydrogens, one from the compound lastly formed and one from the new methane ; we can, however, also take an ethane and join it with a propane, and we obtain the same compound : Fm. 77 Fio. 78 4 6 cJ -o O O C o o o— 4 — t— i — ♦—4 -o Ethane Propane Pentane All the higher homologues as well as the isomers may be formed in this way from corresponding lower homologues of this series. J 8 HYDROCARBONS, OPEN CHAIN We have now had two forms of butane, three of pentane, and five of hexane. The several members of each class can scarcely be distinguished one from another in their chemical properties, the difference being often mainly in the boiling point and in their derivatives. Such compounds of the same elements, in the exact proportion, and in similar quantities, with the like number of the same groups, but differing only in the arrangement of such groups, are termed isomers. As already stated, methane, ethane, and propane can be arranged in but one way; in the hydrocarbons however, that now follow, the more numerous the carbon-atoms are, the more so are the isomers. Butane has two isomers, pentane three, hexane five, heptane nine, octane eighteen, nonane thirty-five, decane seventy-five, and now it goes at an awful pace: 159, 357, 799, &c., according to the law of permutation ; and when we come to the highest known hydrocarbon, pentatriacontane, OjjH^j, they might be counted by millions and billions. This is theory ; the fact is that save on paper the existence of not even fifty of all these millions is really established, The two butanes, three pentanes, and five hexanes are all prepared; but of the nine heptanes only five are known, of the eighteen octanes two, and a little higher up only one of each sort is known, and not always even that — in fact, the more numerous the isomers are expected to be, the fewer of them we find existing. This is remarkable : pro pri/mo, it is lucky for those whose study is chemistry ; pro secundo, it shows there must be a law of limitation somewhere of which we know nothing. But even fifty are a good number, and would form a quaint medley if not put into system. When we look upon the illustrations of these hydrocarbons it must be obvious to the most casual observer that one of the classes looks like a single straight chain : these are the hydrocarbons first treated of, in which substitution always took place in the end-links. They are termed normal paraffins. The other classes of hydrocarbons may be compared to a chain to which side-links are attached, and when substitutions take place in these side-links we forge as it were smaller branching chains on to the main one. According to the mutual position of the carbon-atoms these hydrocarbons may be subdivided into three classes : 1. Iso-pa/raffins, in which not more than one of the carbon-atoms has three others (see 1 and 2, p. 15). 2. Meso-pa/raffins, in which two or more carbon-atoms are bound to three otherSl* 3. Neo-parqffins, in which one of the carbon-atoms is in direct connection wit& (see 4, p. 16). * < From the paraflins, the class of compounds so far described, we can form different sex*ibo ^^ hydrocarbons by further abstraction of hydrogen-atoms in pairs. According to the relative position of the carbon-atoms from which the hydrogen-atoms are removed these hydrocarbons may be divided into two large classes : 1. Unsaturaited hydroea/rhons, in which hydrogen-atoms are removed from neighbouring carbon- atoms. 2. Gydo-hydjrocarbons, in which hydrogen-atoms are removed from separated carbon-atoms. Each of these two classes may be subdivided into several series, according to the number of hydrogen-atoms abstracted and the place which the carbon-atoms take up in the chain. A short survey of their formation will first be given, followed by a specification to suit the purpose of this treatise FOEMATION OF UNSATURATED HYDEOOARBONS 19 FORMATION Unsaturated hydrocarbons If we remove two hydrogen-aioms from two neighbouring carbon-atoms in any of the paraffin- compounds each of the latter will, of course, have a valency free ; but, as mentioned before, free valencies cannot exist in any organic molecule, and the two thus liberated will have to join. We can take as an example pentane : Fig. 79 Fig. 80 U I I 4 I 6 t ? -o 1 e-o T t Pentane Amylene The two carbon-atoms are then said to be tied together by a double bond; but by this it must not be understood that the bond between them has become stronger than before ; on the contrary, a double bond is always open to any offer, and willingly separates to receive and embrace disengaged hydrogen- or other monad-atoms, or even mono-valent groups, or radicals if their offer be more acceptable ; nay, even more than that, the second bond seems to weaken the first so much that when a chain with such a double bond breaks the rupture will frequently take place just at the point where two carbon-atoms are so united. The pictorial representation we have chosen for this state of linking is not meant to give a sketch of the process as it actually takes place. The doings of molecules and atoms can scarcely be understood from geometrical drawings if proper regard be had to their position iu space. The perspective drawing of the simpler molecules is certainly within reach, and some will be sub- sequently given, but they need be very slightly complicated before it will be impossible to make out anything intelligible. If we can convey an idea of their several qualities and properties by geometrical drawings, we shall have achieved as much as one may reasonably expect. Now, as to our representation of the double bond, it is intended to convey the idea of the altered character of the second bond ; the ends of the two valencies being unable to touch each other, the binding cannot be as strong as that of the single bond. Further, the bristling of the valencies (mentioned p. 2) on the same carbon-atom should denote a certain antagonism between them, leaving them in their fullest vigour when at the greatest possible distance apart, but impairing the force by which they attract the valencies of other atoms when compelled to approach each other without full contact being effected. We now return to the further exposition of our hydrocarbons. When we remove only two hydrogen- atoms' from a paraffin-compound we get a series of hydrocarbons with one double bond, but otherwise exactly corresponding in structure to the in series. This series is termed — c 2 HYDROCARBONS, OPEN CHAIN The Oleflnes, or Ethylenes, OnHan They are normal when formed from a normal paraffin by abstracting the two hydrogen-atoma from the two extreme carbon-atoms at one of the ends of the chain ; they are termed isomers if the double binding is effected between any other two carbon-atoms, or in any of the isomers of the paraffins, thus : Fig. 81 3 o #^_i — ,) — () — A-^ o o o Amylene, C5H10 ; b.p. 40° ; from normal pentane (fig. 23, p. 9) is a normal olefine, while the following are isomers : Fig. 82 Mbthtl Ethylene Ethyl LI — o Fig. 83 Methyl CI O-Hh-O KSTHTL -U4 "OMethyl Ethylene Methyl-ethyl-ethylene, CsHm ; b.p. 36° ; from normal pentane (fig. 23, p. 9) Tri-methyl-ethylene, pental, CsHio; b.p. 36-38°; from di-methyl-ethyl-methane (fig. 56, p. 14) Fig. 84 Q U9 Ethylene Isoproftl Iso-propyl-ethylene, CjHio ; b.p. 21°-3 ; from di-methyl-ethyl-methane (fig. 56, p. 14) Di- ethylenes, OnHan-a We can again abstract two hydrogen-atoms from the olefines, and in one of two ways : either from the same two carbon-atoms from which we have already removed two atoms of hydrogen, or from some other pair of neighbouring carbon-atoms. By the first process we get the acetylenes, which will be described hereafter ; by the second, the di-&thylenes are formed. If we take away the two available hydrogen-atoms from the end of the chain most approximate to the existing double bond we obtain normal di-ethylenes ; the removal of any others will result in isomers. Fia. 85 o-L t 0" J L", T o 4 ►— ^ Methyl Butylene, OiHg Methyl-allene is a normal di-ethylene. Mothyl-aUene, CiHg; b.p. 18° FOEMATION OP ETHYLENES 21 If we remove from the same compound two atoms of hydrogen from the other end of the chain we obtain the isomeric compound butine : Fig. 87 Fio. 88 Butylene, C4H3 Butine (vinyl-ethylene), OiHe ; b.p. 20° Tri- ethylenes, OnH2n-4 Again, two hydrogen-atoms may be abstracted from the di-ethylenes, in the same way as before. A normal hydrocarbon of this series would look like this, Fia. 89 La o 6 Methyl-tri-ethylene, CgHs but is not known yet. When the hydrogen-atoms are not all abstracted from the same end of the chain isomers are produced. Such an isomer is ^irylene, in which the abstraction is performed at the other end: Fio. 90 ? t '^ o - 4- _r" ' n y — 4^- 4 - o Pirylene, C^Us ; b.p. 60° Tetra- ethylenes, OnHjn-s Lastly, two hydrocarbons may be removed from the tri-ethylenes as before. Compounds with four double bonds were, however, entirely unknown until Heyerdahl discovered the therapic acid (fig. 770, p. 198), which is no doubt the most important constituent of cod-liver oil, both quantitatively and therapeutically. A normal hydrocarbon of the tetra-ethylene series formed from methyl-tri-ethylene would have this structure : Fig. 91 Tetra-ethylene, C5H4 ; hypothetical Theoretically we might, go on creating double bonds as long as we please, there being no limit but the length of the paper ; practically, however, no more than four double bonds seem to exist. The chain appears unable to endure beyond a certain length, after which it breaks, as it were, by its own weight ; the single binding being, however, more tenacious, a greater length of chain seems to be allowed to the paraffins. 22 HYDROCARBONS, OPEN CHAIN Acetylenes, OnHjn-s Instead of removing the hydrogen-atoms from different pairs of neighbouring carbon-atoms in the compounds with double bonds, we may abstract them from the same two atoms that are already united by a double bond. We then obtain compounds with triple hands, e.g. Fia. 92 t t ) o o () O C) Amylene, C5H10 ; b-P- 40° Fio. 93 Propyl-acetyjene, CgHs ; b.p. 48° This is a normal acetylene for the same reasons that obtained with ethylene and poly-ethylene compounds (vide p. 20), whereas the following are isomers of the same compound : Fio. 94 Valerylene, methyl-ethyl-acetylene, CjHa ; b.p. 44° ; from methyl-ethyl-ethylene (fig. 83, p. 20) Fig. 95 Iso-valerylene (iso-prene), CsHg ; b.p. 28°; from iso-propyl-ethylene (fig. 84, p. 20) Di-acetylenes, OnHjn-e From one of the homologues of acetylene, containing at least four carbon-atoms, we can abstract our usual two atoms of hydrogen. We will illustrate it by taking propyl-acetylene (fig. 93, above) as an example. Fig. 97 Fia. U I O ' c: 3 000 Propyl-aoetylene, CgHa 4. Valylene, OsHs ; b.p. 50° This new compound, valylene, has a double and a triple bond, and forms an intermediate com- pound between acetylene and di-acetylene ; removing two hydrogen-atoms from the doubly united carbon-atoms, di-acetylene is obtained. Fig. 98 Fio. 99 -O Valylene, CsHa Methyl-di-aoetylene, C^^ ; hypothetical FORMATION OF ACETYLENES 23 Tri- and tetra-acetylenes, OnHan-io and OnHan-u In the same way in which we have formed di-acetylenes from acetylenes, tri-acetylenes may be formed from di-acetylenes and tetra-acetylenes from tri-acetylenes. The process need not be repro- duced ; only a representation of these compounds will be necessary. Pia. 100 Fig. 101 Tri-aoetylene, CeHj ; hypotlietioal -O Tetra-acetylene, CjHj ; hypothetical ; for derivatives see Table IV. p. 174 Common to all hydrocarbons with double or triple bonds is, as mentioned p. 19, their ability to take up hydrogen or other monad atoms or mono-valent radicals until all the valencies are thus engaged. By this process the doubly or trebly linked compounds are at last turned into the corresponding paraffin-compounds when unable to take up any more atoms or radicals by simple addition. If we wish to add to the paraffins it can only be done by substitution, i.e. by exchange. If we have, for instance, methyl-di-acetylene, it will first take up two hydrogen-atoms and become valylene. Fia. 102 4 6 Fig. 103 IS Methyl-dS-aoetylene (fig. 99, p. 22) Valylene (fig. 97, p. 22) Adding another two hydrogen-atoms we have pr >^\ o — it 4 6 6 Di-methyl-bntinyl-iso-propyl-methane Fia. 141 Fio. 142 O o~e -O Methyl-iso-propyl-benzene (oymene) , CjoHii ; b.p. 175° ; a constituent of Eoman oumin oil; has been pre- pared from geranial, the aldehyde derived from di-methyl-butinyl-iso- propyl-methane (vide fig. 553, p. 133 ; Ber. xxiv. p. 205) Pia. 143 6 O ,0 Di-iso-propyl-butine + e>-e Methyl-iso-propyl-benzene-di-hydride (limonene ?), OjoHie; b.p. 175° 30 HYDROCARBONS, CLOSED CHAIN Cymene and limonene are natural products, constituents of many ethereal oils, and, again, this is probably the way in which nature forms these rings from open chains, as mentioned p. 26, whilst chemists in most cases take a more or less complex benzene compound on which by various pro- cesses radicals are hooked on, split off, or exchanged. Both because the formation of rings from open chains, specially the more complex ones, is known for comparatively few compounds, and because it is much easier to compare and classify the enormous number of compounds belonging to this class when looked upon as formed by substitution, abstraction, or addition, we also shall, as a rule, regard them as formed in this way. Thus the above two compounds are, as the names indicate, one a benzene ring, the other a benzene di-hydride, in each of which two of the hydrogen-atoms are substituted, one by a methyl-, the other by an iso-propyl-radical. Poly- ethylene derivatives No more than six carbon-atoms in a doubly linked open chain without side-chains can form one rmg, but if there is a sufficient number the chain will make another bend, and two or more — as it were — interlocked rings may be formed, and are terrcied condensed nuclei. Suppose, for instance, we have a chain of nine atoms of carbon linked together in this fashion ; FiQ. 145 6 r A.\ U U I LJ... and the hydrogen-atoms marked 1, 6, 7, and 11 are removed; the straight chain will bend serpent- like, and finally shut up, forming two interlocked rings : one, a benzene ring, the other a pentaphene rmg. Fio. 147 Indene, CJB.^ ; b.p. 180° (Ber. xxiii. p. 3276) Another instance. Suppose we have a chain of ten carbon-atoms like this Pia. 148 6 7 ■oLJ IJ IJ U U. 12 and the hydrogen-atoms 1, 6, 7, and 12 are removed, the bending and closing will appear thus: FOEMATION PROM DOUBLE BONDS Pig. 149 Fio. 150 6 12 81 1 7 Naphthalene, CioHg ; m.p. 80° ; used in the preparation of various dyes, and lor the carbuiation of illuminating gas Further, an open chain of fourteen, eighteen, or twenty-two carbon-atoms would form three, four, or five rings of the same sort. Pm. 152 Fia. 153 Fia. 151 Phenantrene, CnHip ; m.p. 100° Chrysene, CisHi^ ; m.p. 248° Picene, CagHj^ ; m.p. 364° (Ber. xxvi. p. 1751) Picene boils at 520°, i.e. nearly at red heat, and has therefore the highest boiling-point of any known hydrocarbon (B. & S. VI. p. 552). It is the final member of this series, but theoretically there is room for another ring before the circle is closed. Fig. 154 C24H12 It is not found yet, but once found it is sure to beat picene in the point of both melting and boiling. Open chains with double bindings of such length as these ring-formations would require are certainly unknown, but, for all we know to the contrary, they may be momentarily formed preceding 32 HTDROCAEBONS, CLOSED CHAIN the formation of the ultimate compound. Or the ring may be welded from smaller chains which taken together would make up the more lengthy one, just as we are now going to see the same compounds formed from several pieces of acetylene. Derivatives from hydrocarTbons with, triple bonds The triple bond imparts a still greater rigidity to the open chain ; even when alternating with single bonds no closure of the ring has hitherto been effected ; still the benzene-ring can be formed from acetylene, but only by three separate molecules being welded together, a process termed polymerisation. In this case the triple bonds break, double bonds being formed. The process is represented iu this way : Fia. 155 Pig. 156 O " C - -o n Fig. 157 Three molecules of acetylene The triple bonds broken Benzene formed From five acetylenes we obtain, by abstracting two hydrogen atoms, naphthalene. Fig. 158 Five molecules of, acetylene Fig. 159 Naphthalene By the same process we can form phenantrene from seven molecules, chrysene from nine, and picene from eleven molecules of acetylene. GENERAL EEMAEKS ON THE RING-FORMED COMPOUNDS The closing of the chain alters to a great extent the properties of the compound. It becomes very stable, and the ring is not easily broken. Whereas additions to straight chains with double bonds are easily efiected, it is difficult to break the double bond in the ring-shaped compounds, very energetic reactions being required for this purpose. In our pictorial representation this fact is illustrated by the double bonds being brought into contact with one another through the bending, and thus tied together much more strongly than in the straight chain, where they are cmlj approacli- ing each other. RADICALS PROM UNSATURATED AND CYCLO-COMPOUNDS 33 Still, additions (hydration) are possible first of two, then of four, and lastly of six hydrogen- atoms. Pia. 160 Pro. 161 Pre. 162 Pio. 163 O Benzene, CeHe ; b.p. 80°-5 Benzene-di-hydride, CeHs ; Benzene-tetra-hydride, CeHjo ; Benzene-hexa-hydride, b.p. about 80° (Ber. xxv. p. 1840) b.p. 82° (Ber. xxvi. p. 230) CoHia ; b.p. 69° These are the identical compounds we have already formed from open chains (vide figs. 137, p. 28, and 130, p. 27 ; fig. 124, p. 26), and they are termed hyckated benzenes. In return, these added hydrogen-atoms are again easily removed ; those outside the ring are much more readily exchanged against many radicals than those of open chains. Generally, the open chains with double bonds are more capable of additions than of substitutions, the closed chains ac- cepting substikitions more readily than additions. RADICALS We have already (p. 10) given a definition of what is understood by radicals, and specified those from the paraffin series commonly made use of. As we frequently meet with similar groups formed from the other hydrocarbons, an enumeration of these, too, is rather necessary in order to properly understand the language of chemistry. From olefines are derived — Pre. 164 XI Vinyl, C2H3 Fia. 165 Propenyl, O3H5 PiQ. 167 Allyl, O3H5 Pia. 166 U U U I I --0 6 o Crotonyl or Butenyl, G^S, FiQ. 168 U-t .IJ I I, 6 a Butylenyl, O^H, Pre. 169 O i-e Pre. 170 J4 Iso-propenyl, O3HB Iso-orotonyl, C4H7 34 HYDEOCAEBONS, EADICALS Authors are not always careful how they use the nomenclature ; vinyl is by some termed ethenyl (vide fig. 39, p. 11), allyl being occasionally applied to propemyl, sometimes termed iso-allyl; in return jpropenyl becomes allyl, and iso-propenyl, prapenyl. The above names are, I think, those most in use. From tzcet ene are derived — Fia. 171 Fia. 172 Acetenyl, C^H From benzene are derived — Propinyl or propargyl, C3H3 FiQ. r rs A^ y- ^ Phenyl, CeHs FiQ. 176 Cinnamenyl, CgH, Phenylene, CoH^ Fig. 177 Tolyl, C^H, Benzyl, C7H, Tolyl, Xylyl, C^H, Some chemists use the term tolyl for the second of these structures, some for the third ; no agreement has been come to as yet, though there has been no want of proposals. The above figures represent the ortho-radicals, but there are, of course, also meta- and para-tolyls (vide p. 43). SPECIFICATION : ETHYLENES 35 SPEOIPIOATION Having now made ourselves acquainted with the general mode of formation of the different series of unsaturated and cyclo-hydrocarbons derived from the paraffins, we may consider more in detail those of them that have a special interest either to medical science or to the farther development of our treatise. We discuss them in the same order of evolution as on the preceding pages. Oleflnes, CnHan NORMAL The whole series of normal olefines, up to those comprising molecules with sixteen carbon-atoms, are known. Of the still higher homologues those only with eighteen, twenty, twenty-seven, and thirty, and derivatives of the one with twenty-two carbon-atoms, are known to exist, or to have been prepared. The nomenclature of the olefines has been formed by adding the suffix ' ene ' to the end syllable 'yV of the mono-valent radicals of the paraflBus, ethyl, ethylene; propyl, propylene, pentyl, pentyleire, &c., or the syllable 'yl' is changed into ' ene.' The first member of this series is ethylene: Fig. 179 G' m ^ ' ^ "O Then follow : Etliylene (ethene), C^H.; Fig. 180 Fig. 181 AJ4 0-U44 — o Propylene (propene), CgHe ; a gas Fig. 182 Uo o o 6 O Butylene (butene), C^Hj ; a gas Fig. 183 UO o o o Normal or o-butylene, C^Hg O 6 Pseudo- or iS-butylene, OtHg Iso-butylene, C^Hb all three gaseous, with boiling-points between —6° and + 1°. In order to indicate by the names the position of the various carbon-atoms in straight chains a proposal (Ber. xix. p. 160) has been generally adopted for marking the end carbon-atoms a> and m', and the others in succession a, ^, &c., from one end, and a', /3', &c., from the other. The letters of the Greek alphabet also betoken the position of any special bond, beginning from the end with a.. The five links of the next define, amylene or pentylene, OjHjg, may be put togeiher in five different arrangements, and are all actually known. Fig. 188 Via, 189 Q Q Fig. 187 IJ I I O ' 4 ^ ' ^ ■ < H-H »— O or o— »=-=:•-— < ► Normal amylene, propyl ethylene, CsHio; b.p. 39° Iso-propyl e ithylene, C5H10 ; b.p. 21° ; is present in turpentine FiQ. 190 Fig. 191 Fio. 192 a-Methyl-ethyl-ethylene, CsHjo b.p. 36° /3-Methyl-ethyl-ethylene, C^B.^^ ; b.p. 36° — 4,^ . Vinyl-ethylene, butine, C^Ho ; b.p. 20° Fig. 200 Di-methyl-aUene, CsHg ; b.p. 30-40" Fig. 201 ©— U I U . .U II Uo G> Piperylene, CsHg ; b.p. 42° Di-allyl, bexine, CbH^,, ; b.p. 59° Fig. 202 i]un]U(i\i 6/ \(5/ \0/6 An isomer of octadeoatylidene, CigHji {x + y + z = 12) Tri-ethylenes, 0„H2n-4 No normal compound of this class is known. ISOMERS Only a few of recent date have been prepared, e.g. Fig. 203 t.^-^ Pirylene, CsHe ; b.p. 60° and derivatives from two others {linolenic and iso-Unolenic acid) are recognised. Fig. 204 w X 4 (j)LJ(i)U (l) U(} }| Isomers of oota-deca-tri-ethylene, CigHsa (v + w + x + y = 10) Tetra-ethylenes, OnHsn-s No hydrocarbon of this class nor any derivatives were known before the discovery of thercepie acid in cod-liver oil (fig. 770, p. 198). SPECIFICATION : ACETYLENES 39 thns : The structure of the hydrocarbon from which this remarkable acid is derived may be represented Fia. 205 X jfpijfnijfiu ui]i I z Q Isomer of hepta-deoa-tetra-ethylene, 0i,H28 (« + w + cc + y + a = 7) Acetylenes, OnHsn-a NORMAL The first member of this class is acetylene. Pia. 206 Acetylene, C2H2 ; a gas Acetylene possesses an unpleasant smell, and is always present in coal gas, which owes its peculiar odour mainly to this compound. It is most interesting on account of its direct formation from carbon and hydrogen when an electric arc passes between two carbon poles in an atmosphere of hydrogen. The two elements are here, without the agency of organic life, united and formed into a molecule from which the whole organic world may be built up. Curiously enough, the electric spark will again decompose it into its elements. The next members in this homologous series are Fio. 207 Fig. 208 O Fig. 209 AUylene, methyl-acetyl- ene, CgHi ; a gas Ethyl-acetylene, C^He ; b.p. 18° Fig. 210 9 9 O-fE- Propyl-aoetylene, CsHs ; b.p. 48° Fig. 211 O Hexoylene, CeH^o ; b.p. 80° Several of the higher homologues are also known. ISOMERS The better known of the isomers of this homologous series are Fig. 213 9 Fia. 212 9 CEnanthylidene, C,H,j; b.p. 106° Fig. 214 O— O^ -4h-0 or o— C- Crotonylene, OiHe ; b.p. 18° Iso-propyl-aoetylene, iso-valerylene (isoprene, B. <& S. V. p. 491), OgHs ; b.p. 28* 40 HYDROCARBONS, OPEN CHAIN Fig. 215 Q a Q 6 6 Valerylene, CgHs ; b.p. 44° The acetylenes are interesting, too, on account of the change their normal compounds undergo when heated with alcoholic potash. The methyl group at the end of the chain detaches itself and jumps over to the other end, exchanging places with the hydrogen there. This seems to be a general property belonging to all the normal acetylenes (comp. Ber. xxv. p. 2243). The process is thus illustrated : Fia. 216 Fio. 217 X o - «: J \ *>■ 6/6 f The exchange taking place inside the molecule itself and not with an outsider (as is commonly the case), the process is termed intramtolecular change. It is not unfrequently met with in other compounds. It is characteristic of all trebly bound hydrocarbons that with some metals (copper and silver) they form explosive compounds, but only then, if the triple bond is placed at the extreme end of the chain, as in fig. 216; if the hydrogen-atom is replaced by methyl, ethyl, &c., as in fig. 217, the explosive character disappears. This property often affords a clue to the structure of such compounds. _ It will be observed that the general formula of the acetylenes, CnH2n_2, is the same as of the di-ethylenes (vide p. 37). wider sense of the word. These two classes are therefore often put together as isomers in the Di-acetylenes, OnHan-e NORMAL The only known compound of this class is Fio. 218 and of the only two are known. Fia. 219 e— Di-acetylene, C^H^ ; a, gas ISOMERS -O Fia. 220 < > 1 ( ► ( 1 ( 1 Di-methyl-di-acetylene, CeHe ; m.p. 64° Di-propinyl, di-propargyl, CeHa ; b.p. 85° These hydrocarbons have the same general formula, CnHj^^, as the tetra-ethylenes (vide p. 21), and both are quite commonly spoken of as isomers. Their relation, however, is the same as between acetylenes and di-ethylenes (see above). SPEOIPIOATION : ETHYLBNB-AOETYLBNES 41 Tri-acetylenes, 0„H2„.io No tri-acetylene of any kind has as yet been recognised as such. Tetra-acetylenes, OnHjn-u Derivatives of only one normal and of one isomeric hydrocarbon are known. NORMAL Fig. 221 G— C- Methyl-tetra-aoetylene, C9H4 ISOMER Fio. 222 Di-methyl-tetra-aoetylene, Cj„Ho Though there is good authority for the existence of the derivatives from these remarkable hydrocarbons (Ber. xviii. pp. 674 and 2269), they have not been analysed, which is a conditio sine to the more sceptical fraternity of chemists. Mixed double and triple bonds Eor the sake of completeness an example of a normal and another of an isomeric hydrocarbon belonging to this class are here illustrated : NORMAL Fig. 223 ISOMER Fig. 224 o g:3 IX o li -o Valylene, CjHe ; b.p. 50° (!) O Di-allylene, hexone, CaH, ; b.p. 70° There are two more hexones whose structures, however, are unknown; probably their double bond takes up a different place in the chain, or they may be iso-compounds, or belong to the tri-ethylenes (vide fig. 138, p. 29). A series of homologues have their names fashioned after hexone : as heptone, C,Hjy ; octone, CgH,,, &c. 42 HYDROCARBONS, CLOSED CHAIN OYCLO-HYDBOOARBONS There is no cyclo-hydrocarbon specially calling for our attention beyond those already mentioned on pp. 24-33, until we come to the benzene-ring, where there is a wide field open for speculation. These cyclo-hydrocarbons have been considered a class distinctly different from the methane group and its derivatives ; but we have seen how it is developed from, the methane exactly in the same manner as all the rest of hydrocarbons. The class has been termed the cufomatic series because of the sweet odour of the compounds which were first recognised as belonging to this series. But in course of time it has been found that even this distinction does not hold good, as there are as many bad as sweet smelling compounds in one class as in the other. In considering them we make benzene our starting-point, regarding all the derivatives as substitution- or combination-products, and not as derived from open chains, for reasons already stated (p. 30). We will then begin by pointing out that all the links taken singly are perfectly identical, having a double bond on one side, a single on the other, and the fourth valency of each carbon-atom bound to a hydrogen-atom : Fig. 225 therefore when one of the hydrogen-atoms is substituted by a monad atom of another element, or by any mono-valent radical, it is quite indifferent upon which one it is. If we substitute one of the hydrogen-atoms by methyl, for instance, the product will be the same methyl-benzene, on whichever link we effect the substitution. But as soon as we substitute two of the hydrogen-atoms by two methyls it is no longer indifferent where the substitution takes place. Three different positions are then possible : Fig. 228 cM:=L^f^ In the first instance the two carbon-atoms upon which the substitution takes place are neighbours, in the second they are separated by another carbon-atom, and in the third by two. If the methyl be placed on either of the two remaining carbon-atoms one of these relations will be repeated ; therefore there are only three different positions in which two substitutes can be t)laced on BENZENE DERIVATIVES 43 a benzene. The first is said to be an ortho-position, the second a metorfosiiion, and the third a para^ ■position. Instead of writing these in full they a,re generally abbreviated to o-, m-, f-. Lately it has become perhaps more u^ual to number the carbon-atoms from one to six, as shown in the figures above, and the expediency of this is particularly noticeable in more complex com- pounds. Ortho-position would then be designated 1 : 2, 2 : 3, 3 : 4, 4 : 5, 5 : 6, or 6:1; meta-posi- tion would be 1 : 3, 2 : 4, 3 : 5, 4 : 6, or 1 : 5 ; similarly para-position would be 1 : 4, 2 : 5, or 3 : 6. If three hydrogen- atoms in benzene are replaced by the same substituents, there are only three different positions in which they can be placed. For the purpose of illustration we may again make use of our old acquaintance, methyl : Pio. 230 The first of these positions (1 : 3 : 5) is termed symmetrical ; the second (1:3:4) asymmetrical ; and the third (1:2:3) vicinal. Commonly the initials only (s, a, v) are used. By combining the two systems all sorts of positions may be accurately described ; but the figure system is much simpler and is getting more prevalent. After these preliminary remarks we can go on describing a few of the more interesting sub- stitution products. Substitutions being nothing more than a joining of radicals, we will for the sake of classification consider these compounds as combinations of radicals. A. Oombinations with single bonds 1 Benzene radicals (phenyl, fig. 173, p. 34) and paraffin-radicals 2 )> 3 » 4 )) 5 5J 6 )) 7 )) „ ethylene-radicals ,, paraffin- and ethylene-radicals „ acetylene-radicals „ pentaphene-radicals „ naphthalene- and paraffin-radicals (p. 31) mutually (p. 10) (p. 33) (p. 33) (p. 34) (p. 28) 8 Naphthalenes mutually B. Oombinations with double bonds 1 Bi-valent benzene radicals (phenylene, fig. 174, p. 34) and paraffin-radicals 2 „ „ „ „ „ » indene-- „ (p. 30) 3 J )j 55 )> 55 naphthalene-radicals 4 „ „ „ naphthalene- and paraffin-radicals 44 HTDROOABBONS, CLOSED CHAIN A. OomlDinations with single bonds 1. Phenyl-parafflns a. ONE BENZENE AND ONE PARAFFIN The following may serve as instances of tMs combination : FiQ. 234 /J^-\ Methyl-benzene, toluene, C^Ha ; b.p. 110° Ethyl-benzene, CsHjo ; b.p. 136°*5 Fropyl-benzene, C9H12 ; b.p. 157° These are considered normal compounds because the paraffin-radical is derived from a normal paraffin. When derived from an isomeric paraffin they are termed accordingly Fig. 235 iBO-propyl- {vide fig. 32, p. 11) benzene, cumene, CgHja ; b.p. 153° b. ONE BENZENE AND TWO PABAFFmS Two methyls. There are three possible positions, and they are all known : Fig. 236 Fig. 237 Fig. 238 1 : 2 or o-Xylene, CsHjo ; b.p. 142° ; has been used externally in smallpox, erysipelas, &o. 1 : 3 or ns-Xylene, CsHio 1 : 4 or p-Xylene, CaHio ; b-P- 136' BENZENE DERIVATIVES 45 Because they have the same empirical formula as ethyl-benzene, OgH,^, they are said to be isomers of that compound. Methyl arid ethyl. The three possible isomers of this compound have been prepared. It is sufficient to illustrate one of them : Fig. 239 9 1 : 2 or o-Methyl-ethyl-benzene, o-ethyl-toluene, CgHij ; b.p. 158° This compound is an isomer of propyl and iso-propyl-benzene in the same sense as the preceding ones were isomers of ethyl-benzene. Fia. 240. — Mbihtl and Isopbopyl 9 Fig. 241. — Meihyl and Iso-buttl p-Methyl-iso-propyl-benzene (oymene), vide fig. 142, p. 29, CioHj^ ; b.p. 175° Metliyl-jre-iso-butyl-benzene, CnHja ; not yet prepared C. ONE BENZENE AND THREE PAEAFFJNS Three methyls. Here, again, three combinations are possible, and have all been prepared ; Fig. 242 Fxo. 243 Fio. 244 Mesitylene, 1 : 3 : 5 or s-tri-methyl- Pseudo-cumene, 1 : 3 : 4 or a-trimethyl- Hemellithene, 1 : 2 : 3 or w-trimethyl- benzene, CgHij ; b.p. 164° benzene, CsH„ ; b.p. 169° benzene, C»H„ ; b.p. 172° 46 HYDROCARBONS, CLOSED CHAIN These are, again, on account of their empirical formulae, G^B.^^, said to be isomers of ethyl-toluene, fag. 239, propyl-benzene, fig. 234, and iso-propyl-benzene, fig. 235. As benzene can exchange every one of its hydrogen-atoms for paraffin-radicals, there are still a great number of normal and isomeric compounds that need not be mentioned here, except one, viz. mellitene, that being interesting on account of its formation from crotonylene (fig. 212, p. 39) through polymerisation, exactly in the same way as benzene was formed from acetylene (vide p. 32). Fig. 245 O 9 o^i Three molecules of crotonylene Fia. 246 Triple bonds broken Hexa-methyl-benzene, mellitene, Ci^Hj^ ; m.p. 164° Benzenes and methane: d. DI-PHENYL-PARAFFmS Fia. 248 Di-phenyl-methane, C13H12 ; m.p. 26" BENZENE DEEIVATIVBS 47 B&nzenes and ethcme : Pio. 249 Fio. 250 Asymmetrio di-phenyl-ethane, Ci^Hi^ ; b.p. 268° Symmetric di-phenyl-ethane, di-benzyl, CnHi^ ; m.p. 51°-5 e. TKI-PHENYL-PARAFFINS Fig. 251 Benzenes and methane : Tri-phenyl-methane, CisHie ; m.p. 92° Mother substance of an extensive series of dyes : bitter-almond-oil-green, rosanilin, fuch&in, methyl-violets, methyl-green, spirit-blue, aurin eosin, &c. There is also a combination of ethane with four benzenes, tetraiphenyl ethane, the structure of which is in perfect analpgy to the others. 2. Phenyl- ethylenes a. ONE BENZENE AND ETHYLENE Pig. 253 9 Fig. 252. Fig. 254 O O- Vinyl- (fig. 164, p. 33) benzene, phenyl- Phenyl-propylene (fig. 165, p. 88), ethylene, styrolene, styrene, cinnam- O^Hjo ; b.p. 165° ene, OeHs ; b.p. 146° ; occurs in storax (Styrax off.) Phenyl-aUyl (fig. 167, p. 33), OgHio ; b.p. 155° 48 HYDKOGARBONS, CLOSED CHAIN TWO BENZENES AND ETHYLENE Eio. 255 Btilbene, toluyleue, di-phenyl-ethyleue, C14H12 ; m.p. 120° ; mother substance of the cotton dyes 3. Benzenes, paraffins, and ethylenes TURPENTINE OILS TEEPENES AND CAMPHENES A paraffin residue, frequently found to replace a hydrogen-atom in benzene, or rather in toluene (fig. 232, p. 44), is iso-propyl (figs. 32 and 34, p. 11), or one of its immediate derivatives. We have already referred to two such substitution-products (cymene, fig. 142, p. 29, and limonene, or, according to later researches, terpinene, fig. 144, p. 29) ; many similar hydrocarbons are present, either as such or as derivatives, in turpentine and other ethereal oils and in camphors, or are laboratory products. The general features of their structures are pretty well agreed upon, but of the details so much diversity of opinion has existed that there is scarcely another class of organic compounds of which such confusion has been made as of the turpentine oils ; it is only recent in- vestigations (jBer. xxiv., xxvi., and xxvii.) that have thrown a definite light upon some of them. It may, therefore, perhaps be interesting to look into the matter a little more fully than the strict purpose of this treatise otherwise would warrant, and we shall to some extent do so again when we afterwards have to discuss their derivatives. The turpentine oils may be divided into two classes, terpenes and camphenes, both of the empirical formula C,QH,g, and both derivable from hexa-hydrated cymene by abstracting one or two pairs of hydrogen-atoms, either from the ring, or fi:'om the side-chain, or fi-om both, creating either double bonds, as before explained, or a new kind of bonds, described later on. ■ If all hydrogen-atoms are removed in pairs from neighbouring carbon-atoms, terpenes are formed ; but if one of the pairs is removed from carbon-atoms in paror^ositions, camphenes are formed. In order to distinguish the various carbon-atoms and bonds, they are numbered as under : di a> Cymene-hexa-hydride, O10H20 ; b.p. 171°-173° For the purpose of designating the positioii of a double bond, the Greek capital A is employed, followed by the numeral of the bond or bonds, as indicated in the figure above, and in the case of a double bond connecting the side-chain with the ring, the numeral of the ring-carbon is followed, in parentheses, by the numeral of the carbon in the side-chain ; the bond connecting carbon-atoms in para-, or any other, position, for the designation of which no proposal has been made, may, for our purpose, be indicated by the numeral of the carbon-atoms thus connected placed in form of a fraction. TBRPENES 49 Terpenes In formation of terpenes one or two pairs of hydrogen-atoms are removed from neighbouring carbon-atoms : one pair is always removed from carbon-atoms in the ring ; when two pairs are removed, both are, in most cases, abstracted from ring-carbons ; but in one case, at least, one is abstracted from the ring and the other from neighbouring carbon-atoms, one of which is in the ring, the other in the side-chain. When we abstract one pair of hydrogen-atoms from cymene hexa-hydride, a tetra-hydride is formed ; by removing each time a different pair of hydrogen-atoms, six tetra-hydrides may be formed, each of which, however, will always correspond to one of the others. We will, for instance, illustrate the two compounds formed when we remove a pair of hydrogens from carbons 1 and 2, and from carbons 1 and 6. Fio. 258 Fig. 259 41 — (t-« A^ Cymene-tetra-hydride A° Cymene-tetra-hydride As long as there is no disorimination between fronts and backs of these two figures, they are evidently identical, the one seen from the back of the paper being exactly the same as the other from the opposite direction. But supposing the two figures are moving towards the observer, fronts and backs have to be recognised, and then at once a difference is apparent, the double bond being in one figure on the right-hand side, in the other on the left. Now, it is a fact that amongst terpenes and oamphenes two compounds have nearly always been found to have the same chemical behaviour, but to differ in some such physical property as the boiling or melting point; principally, however, in their action on polarised light, one turning it in one direction, the other in the opposite direction, for which reason they are termed dextro- and IsBvo-componnds of the terpene in question. The cause of _ this difference vriU be more fully discussed afterwards (p. 463) ; for the present, the above explanation will suffice to make it intelligible that there may be a difference, though we cannot, with our diagrams, indicate it better than by the two figures above. Just as these two, A' and A", correspond, so do A^ and A^, A' and A*. There are, therefore, three cymene-tetra-hydrides, each with a corresponding compound, viz. FiQ. 260 CYMENE-TETRA-HYDEIDES Fm. 261 Fio. 262 A'^ corresp. to A° A" corresp. to A^ A° corresp. to A* We shall now see which compounds have been assigned to them respectively. A' and A^, fig. 260 : Carvo-menthene, G^^H^g, b.p. 174°-5. A^ and A*, fig. 262: Menthene, 0,oH,g; dextro-compound, b.p. 167°-5; Isevo-compound, b.p. 170°-17r. The correctness of these structures has been placed beyond reasonable doubt {Ber. xxvi. p. 825). A'' and A', fig. 261 : Structures have been suggested as those of menthene {Ber. xxi. p. 459, and xxv. p. 144), but that suggestion can now scarcely be supported; no other, at present, known compound has been represented by fig. 261. Carvo-menthene an4 menthene do not occur in nature ; they are laboratory products. When we remove two pairs of hydrogen-atoms from cymene-hexa-hydride, di-hydrides are generally produced ; but intermediate links, -tii-luydirides^ are formed by removing one of these pairs, partly from the ring and partly fi'om the side-chain, i.e. from carbon-atoms 4 and 8 ; or by removing two hydrogens from one carbon-atom in the ring : 50 HYDROOAEBONS, CLOSED CHAIN CYMENE-TRI-HYDEIDES Fig. 263 Fig. 264 A^-^'"', fig. 263: Terpinolene, 0,oH,s, b.p. ISS'-ISS", has no action on polarised light (inactive). The above structure has, with great probability of correctness, been assigned to the compound known by this name {Ber. xxvii. p. 448). Earlier researches {Ber. xxi. p. 172, and xxiv. p. 1575) gave it the structure of fig. 265. A* -2, fig. 264: Sylyestrene, On,H,5, b.p. 175°-176° (Ber. xxi. p. 172), occurs in Scandinavian and Russian turpentine. The structure A^ • ' has also been suggested, but, for reasons stated on p. 456, neither is very probable. CYMENE-DI-HYDEIDES are formed, as stated, by removing two pairs of hydrogen-atoms, each from two dififerent but neighbouring pairs of carbon-atoms in the ring. Five different arrangements of the double bonds are possible besides a corresponding structure to each of the first four of the following : Fig. 265 Fig. 266 Fig. 267 Fig. 268 Fig. 269 &-iy A^ • ^ corr. to A* • i & 6 i i i A'- • * corr. to A^ • » a^ ■ ° corr. to A A'' • * corr. to A' • ■* A' ■ ** and A^ • ^, fig. 265: Limonene, CigHj^; dextro-limonene (citrene, carvene, hesperidwie), b.p. 175°-176°; IsBVO-limonene, same b.p. The former occurs in a great many ethereal oUs ; the latter is found in some kinds of turpentine oil. Di-pentene (inactive limonene, cinene, cajeputene, di-isoprene, iso-terebentene, caoutchin, di- valerylene), 0,oH,5, b.p. 180°-182°. It occurs in Scandinavian and Russian oils of turpentine, but has also been prepared by mixing equal parts of the two limonenes, and is therefore generally looked upon as consisting of an equal number of dezko- and laevo-limonene molecules, and has consequently no actioli on polarised light, the two limonenes neutraUsing each other. Its structure has been con- clusively proved to be A' ■ ' or A^ • ^ (Ber. xxvii. p. 450). The same structure was formerly attributed to terpinolene, fig. 263 {Ber. xxi. p. 172), and also to iso-terpene (fig. 267) {Jowm. d. russ. ch. G. xv. p. 471). To limonene the structures, figs. 266, 267, 268, and 269, have at various times also been given, as explained below. A' • < or A' • ', fig. 266, is ascribed by one of the authorities (Ber. xxi. p. 169) to limonene, but that interpretation must now be abandoned, and there is no other known terpene to take its place. A'-* or A^-^, fig. 267: Iso-terpene, 0,gH,g (Ber. xxi. p. 171); the dextro-compound, b.p. 178°'3, and the laevo-compound, b.p. 175°. The two iso-terpenes are by some authorities (Ann. ocxvi. p. 236) supposed to be the optically active modifications of terpinolene, as represented by fig. 265 ; but if fig. 263 is the true representation of this compound — and there is scarcely room for doubt — and if the theories to be afterwards (p. 462 &o.) submitted are correct, the structure of terpinolene does not admit of any active modifications. So-eaUed iso-terebentenes are probably identical to iso-terpenes. The same structure TBRPENES 51 A' • ^ or A'* " was formerly ascribed to limonene, fig. 265 (Ber. xxiv. p. 1565), and has also been prognosticated as that of an, as yet, hypothetical terpinene (fig. 268) of a rather higher b.p. (Ber. xxvii. p. 453). A= • " or A3 • s, fig. 268 : Terpinene, 0,(,H,5, b.p. 174° (Ber. xxvii. p. 453), optically inactive. This structure has been ascribed also to limonene (Ber. xx. p. 492), whilst on the other hand an altogether dilEEerent one (A i • I, fig. 275) has been suggested for terpinene. A*-', fig. 269, has been variously made to represent pinene (Ber. vi. p. 439) and dipentene (Ber. xxi. p. 169), but the constitutions of those compounds, as represented by figs. 271 and 265 respectively, are more probable, and therefore no compound at present corresponds to fig. 269. Camplienes (Pinenes) Terpenes, it will be remembered, were formed from cymene-hexa-hydride by removing hydrogens in pairs from neigh- bowing carbon-atoms ; in the formation of eamphenes, one of the pairs to be removed is attached to two oatbon-atoms in para-positions, creating by their removal a diagonal bond, characteristic of the class. In representing this bond pictorially, we are obliged to draw the two respective carbon-atoms together a little, inside the regular hexagon, in order to preserve the lengths of the valencies. For all known compounds belonging to this class only one double bond besides the diagonal bond has been suggested, and thus they may be subdivided into two groups, according as the double bond is inside or outside the ring. a. CAMPHENES WITH THE DOUBLE BOND INSIDE THE RING Only three different arrangements are possible when the hydrogen-atoms are removed from different carbon-atoms : Pig. 270 Pig. 271 Fig. 272 T A* *-2 eorresp. to a«-* A f • " eorresp. to A " • '■ A^-^ and A»-', fig. 270 : Oamphene, OioH,g (Ber. xxiv. p. 1555, and xxv. p. 169) ; a dextro- (m.p. 48°-54°), a leevo- (terecamphene, m.p. 45°-48°), and an inactive form (m.p. 47°) are known. The same structure has by another authority (Jou/rn. d. rvss. ch. O. xv. p. 471) been assumed to represent pinene (fig. 271) ; on the other hand, camphene's constitution has been interpreted also in another way (vide fig. 273). • A*-' and A**, fig. 271: Pinene, terebentine (Ann. ccxxxix. p. 49, Ber. xxi. p. 469, xxv. p. 1112) exists in the three optically different forms as dextro-pinene, australene, b.p. 156°, Isevo- pinene, terebentetie, b.p. 155°-156°, and inactive pinene, b.p. 155°-156°. The two former are the chief constituents of different oils of turpentine. Other structures suggested for pinene are figs. 269, 270, and 272, besides several more, including some with open chains that need not be illustrated here (Ber. xi. pp. 152 and 1698, xxiv. p. 2188, Journ. d. russ. eh. O. x. p. 315). A*-^ and A*-^, fig. 272. This structure has been given to pinene (Ber. xxiv. p. 1539) in preference to fig. 271, formerly suggested by the same authority (Ann. ccxxxix. p. 49). Somewhat related to this group is a structure Fia- 273 suggested for oamphene (vide fig. 270), in which f the iso-propyl-radical is bound to the ring by two ® * ° of its valencies. It is interesting as a connecting link between this group and the following one, in which iso- propyl is converted into propenyl or allyl. For a correct interpretation of this and other structures with diagonal bonds, see p. 53 and figs. 595 and 596, p. 144. A*-A-f R 2 52 HYDEOCARBONS, CLOSED CHAIN &. CAMPHENES WITH THE DOUBLE BOND OUTSIDE THE RINQ We know but three compounds for wHcli structures of this kind have been suggested : Fio. 274 Fia. 275 Fig. 276 T Phellandrene, Oi„Hie ; b.p. 171-172° (Ber. xxi. p. 175) Terpinene, CioHie ; b.p. 179-181° (Ber. xxi. p. 175, xxiv. p. 1577) ; Bee also text to fig. 268 A fi "Tff Laurene, CjoHio ; b.p. 173° {Ber. xxi. p. 176) Oil of i/wrpenUne. The French oil consists almost entirely of Isevo-pinene, which also occurs in Venice turpentine and Canada balsam. Dextro-pinene is contained in American and Scotch oils and sjlvestrene (see p. 48), in conjunction with di-pentene in Scandinavian and Eussian oils of turpentine, obtained from the roots of Firms syhiest/ns. Terebene is oil of turpentine distilled with 5-per-cent. concentrated sulphuric acid, washed with diluted solution of sodium carbonate, treated with chloride of calcium, and again distilled, being converted chiefly into dipentene, having an odour of thyme and terpineol with a dash of hyacinths (vide fig. 436, p. 98). Used as a disinfectant and antiseptic, and for inhalation in bronchitis and winter-cough. Dextro-Umonene is a constituent of the oils of orange-rind, of dill, lemon, bergamot, caraway, and of many other oils. Lcsvo-Hmonene, together with IsBvo-pinene, is present in the oil of fir cones. Dipentene is found in the ethereal oil of the camphor tree. AH terpeues are converted into dipentene through the action of sulphuric acid, and into cymene by iodine. Phellandrene is present in the ethereal oil of Phelkmdrum aguaticum, elemi and eucalyptus oils. All the other terpenes are laboratory products. Beimol, resinol, or rosinol is a liquid fi:om destructive distillation of resin, consisting of hydrocarbons of various constitu- tions. It is used for blenorrhoea, and is an excellent solvent for iodol, aristol, camphor, chrysophanic acid, cocaine, codeine, strychnine, carbolic acid, creosote, and phosphorus. Catramin is turpentine derived from Abies ca/nadensis balsannca. Used for tuberculosis and lupus as subcutaneous injection, and as embrocation ; also internally, and as vapour for inhalation. SESQUI-, DI-, AND POLY-TERPENES Terpenes and camphenes may be considered formed from two molecules of iso-prene, CjHg, by polymerisation, or spontaneous transformation, in a similar way as we have seen benzene formed from three molecules of acetylene, -p. 32 ; the structure of isoprene is, however, not sufficiently 'known, and the process can therefore not be illustrated; but fig. 278 is a suggested structure of a sesqui-terpene. ~ This spontaneous transformation is not limited to two molecules of isoprene ; three, four, or more molecules may unite, and the produce is termed sesqu'i^(C^^'R2^), (^^-(CjQHgj), or jpoly-terpenes (CsaHg^). Colophen is a di-terpene; caoutchouc and gutta-percha, poly-terpenes. Indiarubber is said to have formed spontaneously from isoprene {Gh. & B. xl. p. 870); and as turpentine may be converted into that compound, a possibility is opened for making indiarubber from turpentine. Cadinene, C15H24, b.p. 274° (Ann. ccxxxix. p. 49) DIAGONAL BOND 53 THE DIAGONAL BON"D We meet with this mode of binding for the first time in the terpenes, and it requires therefore few words of explanation. The hexagon is by this bond, as it were, cut in halves. It will be seen that the benzene-ring has changed into two interlocked rings of four carbon- atoms each, of which two are common to both rings. If we stretch out the valencies of each ring in order to get symmetrical figures we obtain this structure : Pia. 280 Pig. 281 which mayj perhaps, better be drawn thus : Terpinene and laurene, for instance, would then have these forms : Pia. 282 Fia. 283 9 o-tr (J Terpinene -O

1» (H— i (h-O o o o ft 6 Q Q Q 9 Methyl-propyl-oarbinol, C5H12O ; b.p. 118" ; secondary alcohol 6 6 Di-ethyl-oarbinol, CbHibO ; b.p. 116°-5 ; secondary alcohol From. jaseudo-pentane (fig. 57, p. 14), four alcohols are possible and known: Fig. 344 Iso-butyl-carbinol, inactive (iso-) amyl-aloohol, C5H12O ; b.p. 131° ; primary alcohol ; chief constituent of fusel oil ; poisonous ; causes the toxic after-effects of intoxication by brandy Fig. 345 Methyl-iso-propyl-carbinol, C5H12O ; b.p. 111-113° ; secondary alcohol Fia. 346 9 9 o a Active amyl-aloohol, OsHuO ; b.p. 128° ; primary alcohol ; turns the plane of polarisation to the left 72 OXYGEN-COMPOUNDS Fia. 347 Q O— Fig. 348 or, hydroxy! changing position with one of the methyls at o - ^ the end carbon : Amylene-hydrate, di-methyl-ethyl-carbinol, CbHijO ; b.p. 102°'5 ; tertiary alcohol ; hypnotic, between paraldehyde and chloral The eighth of possible pentyl-alcohols, according to our theory, has recently been prepared (Oh. Ztg. 1891, p. 15). Theoretically it is formed from tetra-methyl-methane, and its structure is thas illustrated : Fig. 349 (> Tetra-methyl-carbinol, C5H12O ; m.p. 48-50° ; primary alcohol From he^ptane is derived Fig. 850 ftinary heptyl-aJcohol, C^HieO ; b.p. 176° Not much need be said about the rest of mon-acid paraflBn alcohols. Cetyl alcohol or sethal, OjgHg^O, supposed to be a normal hexadecyl alcohol, is in combination with palmitic acid (as ether, mde p. 232), the chief constituent of spermaceti. All normal alcohols up to twelve atoms of carbon are faiown ; but as to their isomers, theory and facts are sadly at variance. Out of 3,133 possible isomers, only sixty are known, and the more we might expect, the less there appear to be. The highest homologue is tarchonyl alcohol, C^QB.^^fi, but between this and dodecyl alcohol only eight alcohols are actually known out of eight to ten billions theoretically possible. MON-AOID ALCOHOLS FEOM ETHYLENES 73 2. ALCOHOLS PBOM OLBFINBS are formed in the same way as from paraffins, but comparatively few are actually known. The first member is formed from ethylene (fig. 179, p. 35) : PiQ. 351 G' 11 Vinyl-alcohol, C2H4O ; primary alcohol ; occurs as an impurity in ether {Ser. xxli. p. 2863) From propylene (fig. 180, p. 35) is derived FiQ. 352 U-.. AUyl-aloohol, propenyl-alcohol CaHeO ; b.p. 96°"6 ; primary alcohol From pseudo-butylene (fig. 185, p. 36) Fig. 353 A U Crotyl-alcohol, CiHgO ; b.p. 117° ; primary alcohol And as samples of secondary and tertiary alcohols : From norrrbal amylene (fig. 187, p. 36) Fia. 354 O- Ul I u 6 6 Vinyl-ethyl-carbinol, C5H10O ; b.p. 114° (Beilst. i. p. 261) ; secondary alcohol Pia. 355 U? 9 (h--<> !► Di-methyl-allyl-carbinol ; CoHiaO ; b.p. 119°"5 ; tertiary alcohol 74 OXYGEN-COMPOUNDS 3. ALCOHOLS FROM DI-ETHYLBNBS A few alcohols belonging to this series are known. From di-methyIr-hitinylr4so-propyl-methane (fig. 140, p. 29) is derived Fig. 356 u Li LJ I Geraniol, C^gH^sO; b.p. 232°; primary alcohol; the fragrant fluid constituent (elaopiene) of Indian oil of geranium When the hydroxyl and a hydrogen at the end of the chain and both hydrogen-atoms on the sixth carbon-atom (from the alcoholic end) are removed in form of water, HgO, and Hj, the compound is transformed into cymene, with a closed chain (comp. figs. 140-142, p. 29). Cymene , From cU-iso-propyl-buHne (fig. 143, p. 29) is derived Fig. 358 ®— »o Bhoduiol, CxoHieO ; primary alcohol ; elsoptene of attar of roses When hydroxyl is removed from one end of the chain, and a hydrogen-atom from the other, the cyclo-hydrocarbon limonene is formed (comp. figs. 143, 144, p. 29). MON-ACID ALCOHOLS FROM ETHYLENES AND ACETYLENES Fio. 359 75 6 6 O Limonene Instances of secondary and tertiary alcohols are Fig. 360 .111] ll.U 6 i> o Di-aUyl-oarbinol, 0,Hi20 ; b.p. 151° ; secondary alcohol Fig. 361 I n I ij o— Methyl-di-allyl-carbinol, OaHnO ; b.p. 158°-4 ; tertiary alcohol / No alcohols derived from tri- and tetra-ethylenes have been prepared. 4. ALCOHOLS FROM AOBTYLENB The only, as yet, actually known alcohol from the acetylene series is propa/rgyl-alcohol ; from allyhne (fig, 207, p. 39) Fig. 362 ©- Propargyl-alcohol, C3H4O ; b.p. 114° ; primary alcohol 76 OXYGEN-OOMPOUNDS B. Di-acid Alcoliols When two hydrogen-atoms in a hydrocarbon with open chain are substituted by hydroxyls, di- acid alcohols are formed. The two hydrogen-atoms must be from different carbon-atoms, because two hydroxyls cannot, as a rule, be joined to the same carbon-atom except when they are, as it were, counterbalanced by strong negative atoms joined either to the same or a neighbouring carbon-atom. For this reason a methylene-glycol Fio. 363 Methylene-glycol ; hypothetical is not known to exist in free state, though there are compounds which must be regarded as its derivatives {e.g. methylal, fig. 481, p. 114). As there are two hydroxyls in these compounds they are either di-primary, or primary- secondary, or di-secondary, &c. 1. ALCOHOLS FROM PARAFFINS: GLYCOLS The first glycol must therefore be formed from etJiane (fig. 16, p. 8) Fia. 364 Ethylene-glycol, CaHgOa ; b.p. 197°; di-pmnary alcohol According to this representation the hydroxyls are joined to ethane by substitution. It may, however, be construed as an addition of hydroxyls to ethylene (fig. 179, p. 35) ; Fig. 365 ff and because it is prepared from compounds obtained in this way from ethylene it is termed ethylene- glycol, and all the other glycols similarly. The nomenclature in this case and in many others is DI-AOID ALCOHOLS FROM PARAFFINS 77 singularly inconsistent and confusing, Witt the name of ethylene is connected the idea of a double bond ; but such bond does not exist in ethylene-glycol, nor in any of the compounds from which it is directly prepared. From propane are derived Pig. 366 Fia. 367 'O o-Propylene-glyool, O^VL^O^ ; b.p. 188° ; primary-secondary alcohol From butane : Fia. 368 i 4+ Fio. 369 j8-Propylene-glyool, OsHsO^ ; b.p. 216°; di-primary alcohol Fia. 370 44 c ) T c ) T T " 1 1 — •fj ( ) i ( 1 1 o-Butylene-glycol, CiHioOa ; b.p. 191° ; ;8-Bntylene-glyool, C^HioOa ; b.p. 203°-5 ; Di-methyl-ethylene-glycol, C^HioOj ; primary-secondary alcohol primary-secondary alcohol b.p. 183° ; di-seoondary alcohol Fia. 371 Iso-butylene-glycol, O^HjoOa ; b.p. 176° ; primary-tertiary alcohol Finally an instance of a di-tertiary glycol from tetror^methyl-eihame (fig. 68, p. 16), an isomer of hexane : Fia. 372 Finaoone, OeHi^Oa ; m.p. 35° ; di-tertiary alcohol All di-tertiary glycols are collectively termed pinacones from this compound. 78 OXYGEN-COMPOUNDS 2. ALCOHOLS FROM OLBFINES From butylene (fig. 181, p. 35) is formed Fig. 373 o-U -O Butine-glycol, C^HgOa ; b.p. 199° ; primary-secondary alcohol 3. ALCOHOLS PROM DI-ETHYLBNBS From di^allyl (fig. 201, p. 38) : Fig. 374 Acro-pinaoone, CeHioO^ ; b.p. 160° ; di-secondary alcohol This compound is not a pinacone (di-tertiary glycol), in spite of its name. Di-acid alcohols from other poly-ethylenes or acetylenes have not been prepared. 0. Tri-acid Alcohols, or Glycerols These alcohols are hydrocarbons in which three hydrogen-atoms have been replaced by hydroxyls. As only one of them can be placed on each carbon, the first alcohol we meet with must be formed from propane (fig. 18, p. 8) : Fio. 375 o^-i^ Glycerin, glycerol, CsHbOs; ni.p. 17-20°; b.p. 290° Glycerin has lately been used in treating hepatic cholic (Gh. & D. xli. p. 762). It requires a temperature below —40° to soKdify glycerin under ordinary circumstances ; but the crystals, once formed, melt at 17-20°. Under certain conditions, not exactly known {e.g. during transport), glycerin does not require so low a temperature to solidify. TR1-, TBTRA-, AND PENTA-ACID ALCOHOLS FROM PARAFFINS 79 A few only of this class are known, e.g. From hutane (fig. 21, p. 9) : Bntyl-glycerin, CiHioOa ; b.p. under 27 mm. pressure, 172' From hescane (fig. 62, p, 15) : FiQ. 377 T T 9 9 T 9 i 1 1 ! 1 i Hexyl-glycerin, CgHi^Os ; b.p. under 10 mm. pressure, 181° No tri-acid alcohol formed from ethylenes or acetylenes is known. D. Tetracid Alcoliols, or Brytlirola Only one alcohol, formed from butane (fig. 21, p. 9), is known: Fio. 378 Brythrite, erythrol, O^HioO^ ; m.p. 126° E. Pentacid Alcoliols Four alcohols are known, and are derived from pentane (fig. 23, p. 9) ! Fia. 879 Adonitol, CsHiaOe ; m.p. 102° 80 OXYGEN-COMPOUNDS Arabitol, its isomer, is a laboratory product ; xylitol and rhamnitol, likewise ; adonitol was lately (Ber. xxvi. p. 633) discovered in Adonis vernalis ; consequently the first pentacid found pre- pared by nature. The isomerisms of the three compounds are stereometrical (comp. p. 463), and the figure represents adonitol. P. Hexacid Alcoliols There are three alcohols found in nature : mcmnitol (three optical isomers), dulcitol, and sorbitol. They are all three formed from normal hexane : Fig. 380 Mannitol, mannite, CoHi^Oa ; m.p. 166° Their difierences are stereometrical. Mannite is widely distributed in nature, and is found especially in the dried juice of the manna- ash (Manna ojicinalis), in celery, sugar cane, rye bread, &c. Dulcitol or dulcite occurs in manna of Madagascar, in varieties of mela/mpyrum, scrophularia, euonymm, rhinantm, &c. Sorbitol or sorbite is found in mountain-ash berries and in the juice of pears, apples, and medlars. The manna that came pouring down on the Israelites in the desert was not this mannite, but probably an edible lichen, Sphoerothallia esculenta (Beilst. i. p. 286). There are several isomers possible, e.g. : Pig. 383 Fig. 382 Fig. 383 Stereo-isomers of each are possible, but only the above mentioned are known. Gr. Heptacid Alcohols The only alcohols known are mannoheptitol or perseitol, prepared from the fruits and leaves haiirus persea (structure, vide fig. 331, p. 68), and glucoheptitol, a laboratory product. of Lam ALCOHOL RADICALS When we remove that, for the alcohols, characteristic group, hydroxyl, compounds remain, most of which are identical with those obtained by removing hydrogen-atoms from hydrocarbons (vide p. 10), i.e. groups whose atoms have a sort of liking or affinity for each other, so that they will rather leave the rest of the compound than part company. Thus we have by the removal of hydroxyl from Fia. 384 Fia. 385 ? C ) d Q — t y-. ) — % ( ) ( ) Met hyl-aloohol Met] ^yi and from Fia. 887 I— &o. Ethyl-aloohol Ethyl corresponding to those derived from hydrocarbons. The mono-valent alcohol radicals are termed alkyls, and the di-valent alkylenes. The free valencies of the latter are of course distributed on different carbon-atoms, because two hydroxyls are never placed on the same carbon-atom in the free alcohols (as explained on p. 76). They are therefore different from the di-valent hydrocarbon radicals methylidene, ethylidene, &c. (p. 11), which have their two free valencies placed on the same carbon atom. If we do not remove the whole of the hydroxyl, but only its hydrogen-atom, a group containing oxygen, and with one free valency, remains, e.g. Pig. 388 (I — ( ) @-t () Methoxyl Fio. 389 Ethoxyl and are termed methoasyl, ethoxyl, &o., which, combined with. other groups, is in nomenclature ab- breviated to methoayy-, ethoxy-, &c. If, on the other hand, we remove a hydrogen-atom from the opposite end of the chain, the remainder is termed hyd/roxy- or oxy-methyl, oxy-ethyl, &o., or generally hydroxy- or oxy-alkyls, with one free valency (mono-valent radicals) Fia. 391 Hydroxy-methyl Hydroxy-ethyl though the designation oxy-methyl is sometimes also used instead of methoxy &o. It is necessary, again, to impress on the mind that these are only theoretical experiments made G 82 OXYGBN-OOMPOUNDS : ALCOHOL RADICALS Methane, CH^ 4 Methyl, CHs Ethane, C^Hg Ethyl, OaHs I T Methylene, methylidene, CHa Methenyl, CH t Ethyhdene, C2H4 Ethenyl, yinyl, C2H3 Allyl, CaHs "2 « Iso-propenyl, O3H5 o . €3 - + Propane, GsHg Propyl, CsH, O Q t Iso-propyl, O3H7 O— (►-O Iso-propyl, CsHt d) O PropyUdene, C3H, Propeuyl, C3H5 Butane, C^H^o Butyl, CiHg t 9 \ Iso-butyl, C^Hg o - m ' O o T (I y a 6 Iso-butyl, CiHg t +i-h Butylidene, C^Hg II Crotonyl, C^H^ f When the three free valencies are without double binding they are termed Glyceryl Butenyl o Iso-crotonyl, C^H, and with the free yalenoies on different carbons, iso-butenyl 4 6 Butylenyl, CiH, Acetenyl, CgH Propinyl or propargyl, O3H3 AROMATIC ALCOHOLS 83 for the sake of convenience. Such radicals do not and cannot exist in the free state with their un- engaged valencies, nor can we practically introduce, for instance, methoxyl or ethoxyl by exchange into other compounds by abstracting water (vide p. 113) unless where a hydroxyl pre-exists. But theoretically we can do many things that at present are practically impossible. Thus, for the sake of showing the development of one compound from another, it is very convenient to say that we in- troduce a methoxyl or ethoxyl, when the intermediate compound containing the needed hydroxyl is only theoretically, not actually, known. It avoids the necessity of representing a hypothetical in- termediate product that as yet exists only in imagination ; for example, when we say that we introduce a meta-methoxyl into anol (fig. 446, p. 100), in order to show the derivation of eugenol (fig. 502, p. 119), it must be understood that we skip the intermediate phenol with a hydroxyl in metaposition, because it is not actually known. The opposite table presents a summary of most of the radicals from hydrocarbons and alcohols with which we have to be made acquainted ; ethylene and its derivatives, though not radicals in the common meaning (as they are independent molecules known in the free state), are often spoken of as radicals on account of their double bonds, with which they can join two free valencies in other compounds without substitution ; they are not specified here, having already been mentioned in full. Hydroxyls may also enter the aliphatic hydrocarbons in their combination with cyclo-hydro- carbons. According to the number and position of hydroxyls the alcohols are classified just as before in mon-acid, di-acid, &c., and each again into primary, secondary, and tertiary alcohols (vide pp. 67—69). We will give the structures of some, enumerating them in the same order as we described the hydrocarbons (vide pp. 24 &c. and 42 &c.). Alcoliols from OomTDiiied. Alipliatic and Cyclo-liydro carbons Alcohols from combinations of tri- and tetra-methylene have not yet been prepared, though some derivatives of such alcohols, viz. aldehydes and acids, are known. I. ALCOHOLS FROM PBNTA-METHYLBNE'S OOMBINATION WITH PARAFFINS One alcohol is known from penta-methylene's (vide fig. 122, p. 26) combination with methane and ethane : Fia. 392 Methyl-penta-methylene-methyl-carbinol, CeHJeO ; b.p. 181° ; mon-aoid, secondary ; has an odour like menthol G 2 OXYGEN-COMPOUNDS II. ALCOHOLS FROM HBXA-METHYLENE'S OOMBINATION WITH PAHAFPIlSrS Ethane united to hexa-methylene (vide fig. 124, p. 26) together with methane forms an alcohol. Fia. 393 Ortho-methyl-hexa-methylene-methyl-carbinol, OgHijO ; b.p. 200° ; mon-S,eid, secondary ; menthol-like odour Note the similarity in structure and physical properties between this and the preceding compound. III. BENZENE-ALOOHOLS A. Alcoliols from Benzene's Combinations witli Paraffins 1. ONE BENZENE WITH ONE PARAFFIN a. Mon-acid alcohols. Methcme's, ethane's, propane's, &c., combinations with benzene (vide figs. 232, 233, and 234, p. 44) form alcohols. Fio. 396 Fio. 395 Pia. 394 Benzyl-alcohol, C^HaO ; b.p. 206°-5 ; Primary styrolyl-alcohol, benzyl-oarbinol, Phenyl-propyl-alcohol, O9H12O ; mon-acid, primary (benzyl, vide CsHioO ; b.p. 212° ; mon-aoid, primary b.p. 235° ; mon-aoid, primary fig. 175, p. 34) AROMATIC ALCOHOLS 86 Isomers. Secondary styrolyl-aloohol, methyl-phenyl-oarbinol, CsHjoO ; b.p. 202° ; mon-aoid, secondary Ethyl-phenyl-carbinol, CoHiaO; b.p. 212°} mon-acid, secondary Fia. 399 Di-methyl-phenyl-oarbinol, CgHuO ; mon-acid, tertiary, hypoth. h. Di-acid alcohols. Styrolene-alcohol, phenyl-glycol, CgHioOa ; m.p. 67° ; di-acid, primary secondary {vide fig. 233, p. 44) 86 OXYGEN-COMPOUNDS c. Tri-acid alcohols. Fig. 401 9 Styoerol, phenyl-glycerol, CgHiaOg ; gum-like mass ; decomposes on heating ; tri-acid, primary di-seconJary {vide fig. 2U, p. 44) Tetra-, penta-, &c., acid alcohols are unknown. 2. ONE BENZENE WITH TWO PARAFFINS a. Mon-acid alcohols. Instances of this sort of alcohols are Fig. 403 Fia. 402 T T 0-H> it !►— e 6 4 6 o-Tolyl-earbinol, CgHioO ; in.p. 54° ; mon-acid, primary ; jp-Cumio-aloohol, OioHi^O ; b.p. 246°*6 ; mon-aoid,' m- and ^-compounds are also known {vide figs. 236, primary (its hydrocarbon, oymene, vide fig. 240, 237, 238, p. 44) p. 45) AEOMATIO ALCOHOLS 87 6. Di-acid alcoliols. Fia. 404 Ortho-position phtalyl-aJcohol, ObHioOs ; m.p. 64°'5. Para-position tolylene-glycol, CaHioOa ; m.p. 112° Di-acid, di-primary {vide figs. 236, 238, p. 44) 3. ONE BENZKNE WITH THEEE PAKAFFINS a. Mon-acid alcohols. From mesihflene (fig. 242, p. 45) Fia. 405 Mesitylio alcohol, O9H12O ; b.p. 220° ; mon-acid, primary b. Di-acid alcoliols. Prom mesiiylene (fig. 242, p. 45) Fio. 406 Mesitene-alcohol, mesitylene-glycol, CgHuOa ; b.p. 190°, 20 mm. pressure ; di-acid, di-primary OXYGEN-COMPOUNDS From pseiido-cumene (fig. 243, p. 45) PiQ. 407 Pseudo-oumylene-alcohol, OaHujOj ; m.p. 77°'5 (97° 5 stereo-isomer ?) ; di-aoid, di-primar; 4. TWO BENZENES AND A PARAFFIN a. Mon-acid alcohols. From di-fhenylr-methcme (vide fig. 248, p. 46) Fia. 408 Di-phenyl-carbinol, CiaHi^O ; m.p. 68° ; mon-acid, secondary From sym. di-phemyl-ethane (vide fig. 250, p. 47) Tolnylene-hydrate, phenyl-benzyl-carbinol, O14H14O ; m.p. 42° ; mon-acid, secondary may also be considered a derivative of toluylene (fig. 255, p. 48) by addition of the elements of water ; hence its name toluylene-hyd/rate. AEOMATIC ALCOHOLS 89 b. Di-acid alcohols. From sym. di-^henyl-ethane (vide fig. 250, p. 47) Fia. 410 Bydrobenzoin, Ci^Hi^^Oa ; m.p. 134° ; di-acid, di-secondary An isomeric compound, iso-hyd/robenzoin, which melts at 119°, also exists. Possibly it is an isomerism, which may be indicated by turning downwards one of the hydroxyls in the figure above. There are a great many similar (physical, in contradistinction to chemical) isomerisms, which will be explained later on (p. 463 &c. ; comp. also p. 8). From di-phenyl-ethane (fig. 250, p. 47) Fig. 411 >tt X t<4- Aoeto-plienone-pinaoone, CieHigOa ; m.p. 120° ; di-acid, di-tertiary As to the name pinaeone see p. 77. The compound may be regarded as pinacone in which two methyls are substituted by two phenyls. 5. THEEE BENZENES AND A PABAFFIN From trryphenyPmethane (fig. 251, p. 47) is derived Fia. 412 Tri-phenyl-carbinol, OiaHiaO J m.p. 159°; mon-aoid, tertiary 90 OXYGEN-COMPOUNDS B. Alcohols from Benzene's Combinations with defines A mon-acid alcohol is derived from ph&nyl-projpylene (fig. 253, p. 47) Fie. 413 Styrone, cinnamic alcohol, phenyl-allyl (propylene) alcohol, C9H10O ; m.p. 33° ; mon-acid, primary occurs in etorax Alcohols belonging to this class have the general formula G^^^.fi. Mention should therefore be made here of an alcohol that possesses such empirical formula, although its structure is not known (and yet chemists have been acquainted with it ever since the year 1788), viz. cholesterin, its homo- logues and isomers. It is widely spread in nature, occurs in blood, bile, brain, nerves, spleen, and generally in the cells of the living organism ; it is found in cod-liver oil, milk, eggs, &c. ; gall-stones consist almost entirely of it ; lanolin, or wool-fat, is almost exclusively cholesterins, either in the free state or as ethers united with stearic acid. It is a mon-acid alcohol, nearly related to the terpenes and camphors, perhaps also to the acids of the bile, glycocholic and taurocholic acid. From the molecular refraction the conclusion is drawn that there are four double bonds, and chemically it behaves like tertiary alcohols. The ultimate analysis and the determination of molecular weight (by Raoult's method) give numbers closely approximating those of OjgH^jOH {Monatsh. xi. pp. 61-70). Isomers: phytosterin in seeds, and generally in the vegetable kingdom; isocholesterin in wool-fat; paracholesterin in a fungus; caulosterin in the yellow lupin; and daucosterin in carrots. A higher homologue, O27H45OH (Monatsh. ix. p. 421), and another, OjgH^jOH (/. Gh. Soc. Iviii. p. 757), have also been obtained. Of the remaining alcohols formed from combinations of the aliphatic and cyclo-series there are but few, and no occasion for mentioning more than the following (two henzenes connected through ethyl by four of its valencies, or through two methyls by two valencies of each, in which case it may be considered three interlocked benzene rings). AROMATIC ALCOHOLS 91 O. Alcohols from Anthracene (fig. 307, p. 59) Fia. 414 Anthranol, O14H10O ; m.p. 163°, under decomposition ; mon-aoid, tertiary FiQ. 415 Hydroxy-anthranol, OiiHioOa ; m.p. not ascertained ; di-acid, di-tertiary From cmthracene di-hyckate 1 Fia. 416 Hydrantliranol, C14H12O ; m.p. 76° ; mon-acid, secondary SEOOND GROUP PHENOLS When hydroxyl substitutes one or more hydrogen atoms in the bemiene-niwhus, the resulting compounds behave in many ways differently from alcohols, and are therefore given a special name, phenols. They are allied to tertiary alcohols, as they behave like them towards oxygen, but differ from them in most of their other characteristic qualities. We will discuss the entering of hydroxyl into benzene and its derivatives, in the same order as the latter have been described before under Hydrocarbons. 92 OXYGEN-OOMPOUNDS Ab in the case of alcohols, they are classified accordhig to the compounds they are derived from, each of which classes is subdivided into mon-aeid, dv-add, &c., up to hex-acid phenols. We commence, then, with replacing hydrogen by hydroxyl in benzene. I. Benzene -phenols A. Mon-acid Phenols All hydrogens in benzene being of equal value, there can be but one member of this class : PiQ. 417 Phenol, carbolic acid, CgHgO ; m.p. 41° ; occuis in tars from wood, coal, &e. ; is found in small c^nantities in the nrine and castoremu ; antiseptic Crude carbolic add contains scarcely any carbolic acid (vide p. 95). B. Di-acid Phenols There are three phenols in this class according to the dififerent positions of the hydroxyl : ortho-, meta-, and para-phenols. Fia. 418 Fio. 419 Fig. 420 Pyrooateohin, catechol, ortho-dioxy- benzene, CeHeOsi ; m.p. 104°; poisonons; used as a photo- graphic developer Besorcin, meta-dioxy-benzene, CsHgO^ ; m.p. 119° ; powerful cauteriser, anti- septic, ana^esic, and htemostatic. Employed in the manufacture of fluo- rescein and eosin, two important dyes Hydroquinone, para-dioxy-benzene, ObHsOs; m.p. 169°; rapid and delicate developer in photo- graphy; antipyretic and anti- septic BENZENE-PHENOLS 93 O. Tri-acid Phenols There are three of them corresponding to the positions 1:2:3 (vicinal, vide p. 43), 1:8:5 (symmetrical), and 1:3:4 (asymmetrical). FiQ. 421 Fia. 422 Pyrogallio acid, pyrogallol, CaHgOa ; m.p. 115° ; antiseptic ; very poisonous ; absorbs oxygen powerfully ; formerly much used in photography as a developer Phlorogluoin (-ol), OaHoOa; m.p. 217°; colours ligninred, and is therefore used as a test of wood-pulp in paper, also in medicine as an antiseptic and antipyretic Fio. 423 Hydroxy-quiiol, oxy-hydro-quinone, CeHjOa ; m.p. 140° PUoroglucin seems capable of assuming two forms according to the character of the substance with which it comes in contact. The second form is a re-arrangement of the oxygen- and hydrogen- atoms, including the double bonds, and is represented thus : Fro. 424 Desmotropic form of phloroglucin ; contains three ketones {vide p. 138) instead of three hydroxyls Such re-arrangement is termed desmotropism when a change in the bonds is involved ; if not, it is termed tautomerism, which is, however, frequently used in both cases. 94 OXYGEN-COMPOUNDS D. Tetr-acid Phenols Fio. 425 Tetra-hydroxy-benzene, CeHeOi; m.p. 148-220° E. Pent-acid Phenols Eia. 426 Quercite, CeHisOj ; m.p. 225° derived from hydrated benzene (benzene-hexa-liydride, fig. 124, p. 26), and is, therefore, strictly not a phenol, but a hydrated phenol. Finite seems to belong to this class, but the difference in structure is not sufficiently understood. F. Hex-acid Phenols PiQ. 427 Hexa-hydroxy-benzene, CeHaOe ; deoomposes by heating without melting Inosite, phaseo-mannite, sennite, matezite, dambose, OgHj^Og ; m.p. 210°, is hexa-hydroxy-ben- zene-hexa-hydride, or quercite in which all six hydrogens have been replaced by hydroxyls. It is found in the muscles of the heart, in the lungs, tibe milt, the liver, the kidneys, the braia, and in the urine ; also in plants. TOLUENE-PHENOLS 95 II. Toluene-plienols From toluene (fig. 232, p. 44) several important phenols are derived : A. Mon-acid Phenols Three are possible : Fia. 429 Ortho-oresol, C^HeO ; m.p. 30° Meta-eresol, CjHeO ; b.p. 203' Para-cresol, C^HbO ; m.p. 36° 0- and p-Cresol is found in the urine of horses, ^-cresol also in the human urine during some diseases. They are all found, together with carbolic acid, in coal-tar, from which they are produced by distillation. The better sorts of what is called crude ca/rholic acid (soluble in a solution of caustic soda) contain scarcely any carbolic acid, but are mixtures of cresols, the carbolic acid having been already distilled off on account of its higher value. The crude cresols are little used as such, because they are but slightly soluble in water, and have a higher specific gravity. There are in use the so-called ' carbolic lime ' (crude cresols mixed with lime) and ' carbolic powder ' (cresols mixed with clay). On the other hand, after having been brought into a soluble form, they are largely employed as disinfectants. Moderu Disinfectants Of these there are a good many preparations that naturally divide themselves into two classes : 1, those which contain hydrocarbons and other tar compounds, and therefore form a milky fluid when mixed with water ; and 2, those free from these admixtures, and which are therefore entirely soluble in water. Some of the preparations most in use are — Artmann's Greolin Sa/prol 96 OXYGBN-OOMPOUNDS 1 . 1 „ 7 7 7 TT- 7-.,,, , /Mixtures of resinous soap with cresols, hydrocarbons, 1st class: S^oUrbol IT, _ Littles ^^^ pyridine-bases, originating from the coal-tar. Fluid, Jeyes Bisir^edcmtJ rpj^^ ^^^^^^^ ^^^^^^ dissolved in the dilute resinous Brockmanns Oresohn,] ^^^ ^j^^ hydrocarbons separate and make the Pe Allyl-ether (a simple ether), CeHmO ; b.p. 82° and from vinyl- (fig. 351, p. 73) and ethyl-alcohol Fia. 477 4=1 Vinyl-ethyl-ether (a mixed ether), C^HgO ; b.p. SS'S Theoretically we look upon an ether as an alcohol-radical joined to an oxygen-compound ; thus we consider methyl-ether as composed of methyl and methoxyl (vide p. 81), and ethyl-ether as an ethyl joined to ethoxyl, &c. We do that, as already mentioned, for convenience' sake, because these oxy-groups frequently occur as if they were joined to an alcohol or phenol-radical. 2. Ethers from Di-acid -Alcohols Di-acid alcohols (vide p. 67) can also form ethers, and, having two hydroxyls, can form two series, according as one or both of them are joined to alcohols. Methylene-glycol does not exist, for the reason, already set forth (p. 76), that two hydroxyls on the same carbon-atom will immediately form water. Fig. 478 Fio. 479 G — ®— O Methylene-glycol ; hypothetical i Aldehyde and water But if we could, at the moment when methylene-glycol should be formed, place two alcohols to take the two hydroxyls under treatment, like two policemen taking two brawlers in charge, two molecules of water would be separated, and the structure capable of existence. Fig. 480 9 Fig. 481 -@ — O Methyl-alcohol Methylene-glycol Methyl-aJcohol Methylene-di-methyl-ether (methylal), CaHsOa ; b.p. 42° ; hypnotic ; recommended in delirium tremens; for inluilation and subcutaneous injection ; mixed with chloroform as an anssthetic ; antidote to strychnine ALIPHATIC ETHERS 115 In the same way is formed metliyleiie-di-etliyl-etlier, and also several ethylene-ethers, where the hydroxyls are not in combination with the same carbon-atom. '" Alcohols from ethyKdene (fig. 36, p. 11), where the hydroxyls are placed on the same carbon- atom, have not been prepared in the pure state ; still it is not improbable that they exist in aqueous solution. Anyhow, ethers may be formed from them in the same fashion as they were formed from methylene glycol : 9 FiQ. 482 ( ) ( Ct—-4 > ^^ ef i ^ C Methyl-alcohol Ethylidene-glycol I Laother is Ethyl-aloohol Methyl-ethyl-acetal, CsHuOj ; b.p. 85° Pig. 484 9 ri.. i * ^^ < ) c 5 a () ( ) ( > < ) o o Acetal, di-ethyl-aoetal, CeHiiOa ; b.p. 104° ; hypnotic Ethers being alcohols from which water is abstracted, there is another formation (intramolecular) of ether from glycol-alcohols, one molecule of water being eliminated from one molecule of glycol. fio. 4S5 Fia. 486 FiQ. 487 O— <► or Ethylene-glycol {vide p. 76) = Bthylene-oxide, C2H4O ; b.p. 13°-S Compounds similarly constituted are termed alkylene- oxides. This is a sort of intra-molecular ring formation, which is further developed when two molecules of ethylene-glycol join, in consequence of the separation of two molecules of water. Fig. 488 Fig. 489 Q

->-. Secondary propyl- + Hydrogen-^ alcohol peroxide Di-methyl-ketone + water 128 OXYGEN-COMPOUNDS The illustration is a sort of perspective drawing, and in order to avoid that as much as possible I prefer representing the oxygen-atom in a position analogous to that of aldehyde, consequently thus : Fis. 517 Di-methyl-ketone This is perfectly justifiable, and a little consideration will show that it is in thorough accord with our theory. We have already several times (vide p. 8) mentioned that, according to almost conclusive evidence of all known facts, each of the carbon-atom's four valencies is of equal value, and that no chendcal difference results from the way we arrange the linkings around a carbon-atom. It is a matter of taste, or convenience, which carbon-atom we prefer to consider ending the chain, as far as chemical properties are concerned ; the remaining part of the chain must be looked upon as a side-chain. In the secondary propyl-alcohol we may regard as an end-link that carbon-atom to which the hydroxyl is joined, and which has then on the other three sides respectively a methyl, a methyl, and a hydrogen-atom. We can arrange the three linkings in this way : Pio. 518 Secondary propyl-alcohol By now removing the two hydrogen-atoms as indicated, the ketone will have this form ; FiQ. 519 Di-methyl-ketone and stretching out the pendulous methyl-leg to a horizontal position, a perfectly legitimate operation, we have the figure as represented above. Fio. 520 ( O 1 I (> Di-methyl-ketone FORMATION OF ALDEHYDES AND KETONES 129 I have gone so fully into tbe explanation of this seeming sleight of hand, because we shall con- stantly meet with ketones formed in the same way, and I do not like my readers to think that I am unduly trying the patience of ' the long suffering ' paper. We may now proceed to the third case, hydrogen-peroxide's reaction on tertiary alcohols. For that purpose we take the tertiary amylene-hydrate (fig. 348, p. 72). Pio. 521 O o- Amylene-hydrate As the hydroxyl's carbon-atom is surrounded on all other sides by carbon-atoms, neither aldehyde nor ketone can be formed, because the former requires for its formation two, and the latter one, removable hydrogen-atoms directly connected with the hydroxylic-carbon-atom. In order to get a free valency to satisfy the cravings of the oxygen-atom, after hydrogen- peroxide has deprived it of its hydrogen, it has no other expedient but to sever its connection with the part of the chain next to the hydroxyl. Hydrogen-peroxide now reacts also on the part split off, takes away one of its hydrogens, and another hydrogen-peroxide splits up into three parts : a hydrogen, an oxygen-atom, and a hydroxyl. The two latter occupy the vacancies. The process rendered in words seems rather comphcated, but an illustration will show how simple it really is. Fio. 522 O— @— —# — o Fia. 523 Water O— @— O Pio. 524 9 O-HI 1 ►-J o o O"—^— ,—^~..Q Legs outstretched : Di-methyl-ketone Fio. 525 Q«-# — O Water O— <► Di-methyl-ketone Acetic acid K 130 OXY&BN-OOMPOUNDS It will readily be seen that hydrogen-peroxide reacts exactly in the same way on all three sorts of alcohol ; that the results turn out to be of different characters is entirely due to the presence and number of hydrogen-atoms attached to the carbon-atom attacked, or to their absence. In all cases Fig. 527 the figure \^^ (carbonyl) is formed; in aldehydes it is accompanied by one hydrogen-atom Fia, 528 Fig. 529 *— ^•—•"H^C— wQ ^ ¥^ in ketones by none 1 ^^ L , ; we can, therefore, always recognise an aldehyde by the former figure, and a ketone by the latter. An aldehyde can never be formed from the benzene-nucleus itself; as three of the carbon-atom's valencies in aldehyde are taken up by the oxygen and hydrogen, there is only one valency left fi^ee for joining other atoms in a chain ; that chain must, therefore, by necessity, be an open one, and the aldehyde-carbon must always form the end-link in the chain. A ketone-link, on the other hand, having two valencies free, can form a link in both open and .closed chains, but can never form an end-link. SPEOIFIOATIOJSr ALDEHYDES Fig. 530 Fig. 531 Index, o^ (^y „o Chemical symbol, CHO 1. Aliphatic Aldehydes a. Aldehydes from ParafB.ns Though every primary alcohol is capable of forming an aldehyde, not many have been prepared. The first of these is formed from methyl- alcohol (fig. 336, p. 69). Fig. 532 Fig. 533 Methyl-aldehyde, formic aldehyde, formaldehyde, CH2O ; a gas ; antiseptic, more powerful than corrosive sublimate {C(ympt. Bend. cxiv. p. 1278) ; it is remarkable as the compound from which a carbohydrate (sugar group, vide p. 153) was first synthetically prepared Methyl-aldehyde is strongly inclined to polymerise (vidLe p. 32), so much so that it has hitherto been impossible to prepare the pure aldehyde. To make this polymerisation process better understood, we shall have to resort to the perspective drawing of the aldehydes. If we look upon ALDEHYDES 131 the formation of methyl-aldehyde as derived from methyl-alcohol by abstracting that hydrogen which is opposite the hydroxyl, we have a figure which perhaps is more correct, but less perspicuous because perspective. FiQ. 534 Fio. 535 •<-o Croton-aldehyde, CiHeO ; b.p. 104" Oroton-aldehyde may also be formed from two molecules of aldehyde, which first polymerise, forming an intermediate compound a Idol, and then lose a molecule of water Fio. 550 Fia. 551 t I * 1 9 Fio. 662 6 O A 6 6 o o o Two molecules aldehyde 6 6 Aldol, (S-hydroxy-butyr-aldehyde less one mol. water, syrupy liquid; b.p. 90-105°; 20 mm. o O Croton-aldehyde ^ Singly-linked compounds containing hydroxyl besides the aldehyde-group are collectively termed aldols (contracted irom aldehyde-alcohol). When each carbon-atom, except the aldehyde index, is provided with a hydroxyl, the compound is termed a ea/rbohydrate. From gercmiol (vide fig. 356, p. 74) ; Fio. 553 T LJLi <> Geranial, CigHiaO {Ph. 0. xxxii. p. 221 ; Ber. xxiv. p. 205) ; constituent of oil of orange peel, of oitronella, lemon, &o. 134 OXYG EN-OOMPOUNDS 2. AldetLydes from Cyclo-corapouiids Benzene itself cannot form an aldehyde (vide p. 130). A few aldehydes derived from benzene-alcohols have a claim on our attention. a. Aldehydes from Benzene and Paraffin From benzyl alcohol (fig. 394, p. 84) an important aldehyde is derived — oil of bitter almonds. Benzoic aldehyde, benz-aldehyde, oil of bitter almonds, C^HgO ; b.p. 179° ; is prepared on a large scale frouL toluene (fig. 232, p. 44) b. Aldehydes from Benzene and define From styrone, cinnamic alcohol (fig. 413, p. 90) : Fig. 555 Cinnamic aldehyde, phenyl-acrolein, CgHgO ; b.p. 247° ; is the chief constituent of oil of cinnamon ALCOHOL- AND PHENOL-ALDEHYDES 135 3. Alcoliol-aldeliydes The aldehydes just discussed were formed from mon-acid alcohols, or benzene alcohols, but poly- acid alcohols and phenol alcohols can form aldehydes as well ; with their alcoholic hydroxyls they possess, however, at the same time, the character of an alcohol, or phenol, and an aldehyde. We have already seen the formation of one of the alcohol-aldehydes, aldol (fig. 550, p. 133), and we shall see more of them collected into one group, the carbohydrates (p. 151). There is now only one more to mention: glycoUic aldehyde, derived from ethylene glycol (fig. 364, p. 76) : Pia. 556 -o GlyooUio aldehyde, O2H4O2, syrupy liquid It has not been isolated yet, and is known only in aqueous solution. It has the property so characteristic of aldehydes, that of polymerising (Ber. xxv. p. 2549). Fia. 557 Pig. 558 000 Two molecules glycoUio aldehyde Erythrose CiHgO^ Brythrose is a tetrose, a carbohydrate. For those alcohol-aldehydes which are known as carbohydrates vide p. 151. 4. PtLenol-aldeliydes Erom saligenin (fig. 461, p. 106) : Fio. 559 Salicylic aldehyde, C^HeOa ; b.p. 196° is contained in the flowers of the difierent varieties of Spircea. 1^6 OXYGEN-COMPOUNDS From anisic alcohol (fig. 509, p. 122) we obtain a phenyl-aldehyde-ether : Anisic aldehyde, methozy-benz-aldehyde, CgHgO^ ; b.p. 247° and from, protocateohuic alcohol (fig. 463, p. 106) a phenol-aldehyde : Protocateohn-aldehyde, CjHeOa ; m.p. 150° From vanillic alcohol (fig. 510, p. 123) by oxidation, or from protocatechu-aMehyde (above) and methyl alcohol in meta-position is formed a phenol-aldehyde-ether: Vanillin, methyl-piotocatechuic aldehyde, CgHaOa ; m.p. 80° PHENOL-ALDEHYDES 137 Vanilla owes its aroma to vanillin, the crystalline coating on the fruit of the vanilla. It is now made artificially on a large scale from the cambium sap of firs and pines (vide coniferyl alcohol, fig. 511, p. 123), or from iso-eugenol (fig. 503, p. 120). It may also be prepared from wood-tar (vide guaiacol, fig. 499, p. 118). The preparation of artificial vanillin from coniferyl alcohol is based upon the curious behaviour of all benzene-compounds, with an aliphatic radical as side-chain, no matter what this radical may be, whether a long or a short chain, a saturated or unsaturated radical ; on oxidation the whole chain is pulled to pieces right down to the last carbon-atom, which, however, remains with the benzene-ring. The chain is converted into acet-aldehydes, acetic or carbonic acid; the carbon-atom remaining with the benzene-ring is transformed into carboxyl or aldehyde according to the force of oxidation. In the case of coniferyl-alcohol the allyl-radical is burnt down, as it were, to formic aldehyde. Vanillin is besides found in the beet sugar, asparagus, Siam benzoin, and asafoetida in small quantities. If we join methyl-alcohol to the para- and not to the meta-hydroxyl in protocatechu-aldehyde we obtain Iso-vanillin, CeHsOa ; m.p. 115° ; a recently patented compound {Ph. C. xxxii. p. 78) When we abstract two hydrogen-atoms from methyl and hydroxyl in vanillin or iso-vanillin, exactly as we performed the operation on eugenol in order to obtain safrol (vide fig. 504, p. 120), the result is a compound termed piperonal. Piperonal, protocatechu-aldehyde-methylene-etlier, OgHsOs ; m.p. 37° ; occurs in the seeds of Piper nigrum ; antieeptio and antipyretic; smells strongly from coumarin (Tonquin bean), and is therefore used in the perfumery trade as heliotropin 138 OXTGBN-OOMPOUNDS KETONES Fia. 565 Index, —•—I or Carbonyl Ketones may be formed from alcohols, benzene-alcohols, phenols, and phenol-alcohols (vide p. 130). 1. Ketones from Alcohols A ketone must have at least three carbon-atoms, and the alcohol from which it is to be formed must be a secondary alcohol ; consequently the first ketone we meet with is derived from seconda/ry propyl-alcohol (fig. 339, p. 70). Pig. 566 (> o Acetone, di-methyl-ketone, CgHeO ; b.p. 56°-5 Unlike aldehydes the ketones do not polymerise, but their most remarkable property is an inclination to condense, i.e. two or more molecules join, with elimination of water forming a new compound. Thus two molecules of acetone condense forming mesityl-oxide : Fia. 567 +ti*4 Y* ^ ^ J Pia. 568 -O ll^ -o Two molecules of acetone O" ® "O Mesityl-oxide, iso-propylideue-ketone, CsHijO ; b.p. 130° ; peppermint-smell By eliminating hydrogen instead of water we (theoretically) form quinone (vide fig. 584, p. 142), also, perhaps, one of Nature's inscrutable ways which we have not yet succeeded in imitating. KETONES 139 Fig. 569 Fig. 570 G- O o •o •-© •o Two molecules of acetone Quinone, CeHiOa ; m.p. 116° If three molecules of acetone join, and two molecules of water are eliminated, we obtain a compound termed phorone Fio. 571 FiQ. 572 9 o 9 9 o n. 4 -o O" # "O o — •— e t -O 4- o f3 + o-^y o •o = ^uJ'^.LJ I. Three molecules of acetone Phorone, acetophorone, CgHnO ; m.p. 28° ' By elimination of three molecules of water we obtain mesitylene (vide fig. 242, p. 45) Pre. 573 Fia. 574 9 9 Q< Three molecules of acetone Mesitylene Assisted by this remarkable property of the ketones, it has been possible synthetically to build up a number of cyclo-derivatives. Mixed ketones are those which have a different number of carbon-atoms on each side of the carbonyl. From methyl-ethyl-carbinol : Pia. 575 ' Methyl-ethyl-ketone, O^HbO ; b.p. 81° ' Some text-books give to phorone the structure (0H3)2C = CH — C(CH3) = C.H-C0-CH3, but having regard to its formation from a compound, nitrosotriacetonamine, the above structure appears more probable (vide B. <& S. I. p. 573, and Beilsl, i. p. 822 ; also Ber.xiv. p. 852). 140 OXTGEN-COMPOUNDS Di-ketones are formed from di-acid alcohols. They are distinguished as a-, /S-, or 7- (1 : 2, 1 : 3, 1 : 4) di-ketones, according as the carbonyl- groups are close together or separated by one or two carbon-atoms. Di-acetyl, di-keto-butane, C^HaOt ; b.p. 87° ; a-di-ketone Fig. 577 ? <^ ? <^ ? O - f ■ ' • • •— Q 6 O Aoetyl-acetone, CsHgOs ; b.p. 136° ; ;3-di-ketoue Fig. 578 t-H EH Ph < Pi m pa IS .a S ...^i^K. e9 /o n EH .S •c EH CaHso . 4O9 C„H,„-40, \ \ W CnHao - 4O7 CuHjj.jOb (1 /o.^4|^^ C„H»„ . jOo O.H„ C„H2„ . 2O5 o-^ "f • • »^ &-o C„H2„.s04 L^^ 0„H,„0, C.H,„Os O.H,„0, CA.O^ 0„H,„03 AOIBS 10 u 12 13 14, 15 16 17 03 Oa/rbomc CH-0, Foimic CH2O3 Qlyi CJ 0.1 Ac Ool bihydroxy- jecoU!Ca O19H38O4 Nondeoylio OisHgaOa Aiachidio OaoHioOa iso- ehem Belienio OaaHiiOi, Missing Page INDEX OP ALIPHATIC ACIDS ON TABLES la AND lb Acetic 17 — 6 Aconitio .... 23—/ Acrylic 18— c Adipio 9—/ AUyl-sucoinic . . . 20 — g Angelic .... 18— e Aposorbic .... 6 — e Arabonic .... 13 — e Arachidio .... 17— r Azelajc .... 9 — i Behenic .... 17 — s Behenolic .... 28 — s BrassyUo .... 9 — Im Butyl-acetylene-carboxylic . 28 — g Butyric .... 17— d Caprlc 17 — j Caproic .... 17 — f Caprylic .... IT—h Carbo-gluconic . . . 11 — g Carbonic .... 16 — a Citric 3—/ Crotonio .... 18— d Deoylenic .... 18— j Desoxalic . . . . 2 — e Di-allyl-acetio . . . 24 — h „ „ oxalic . . . 25 — h Diaterebio .... 8 — g Di-hydroxy-adipic . . 7 — f butyric . . 15 — d caproic . . 15 — / heptylic . . 15 — g iso-oitric . . 1—/ jeooleio . . 15 — g maleic . . 22 — d stearic . . 15^) tartaric . . 5 — d undecylic . . 15 — k valeric . . 15 — e Di-iso-amyl-oxalic . . 16 — Z Elseo-margaric . . . 24 — o Erucio 18 — s Erythro-gluoinio . . . 14 — d Ethenyl-tri-oarboxylio . . 4 — e Formic .... 17 — a Gluconic .... 12—/ Glyceric .... 15 — o Glycollic .... 16—6 Glyoxalio .... 15 — 6 Hexa-hydroxy-stearic . . 11^^ Hydro-muconio . . . 20—/ Hydroxy-butyrio . . . 16— d „ caproic . . . 16—/ „ caprylic . . 16 — h „ citric . . . 2—/ „ crotonic . . 19 — d „ decylic . . . 16 -/ „ eruoic . . . 19— s „ glutaric . . . 8— e „ hydro-muconio . 21—/ „ hypogoBic . . 19 — n „ itaoonic . . 21 — e „ margaric . . 16 — o „ myristio . . 16— m „ nonylic . . . 16 — i „ cenanthylic . . 16 — g „ palmitic . . 16 — n „ propionic . . 16— c „ stearic . . . 16— p „ suberic . . . 8 — h „ valeric . . . 16 — e Hypogieic .... 18 — n Iso-di-hydroxy-behenlc . . 15 — s Itaoonic .... 20 — e Jecoleio .... 18 — g Laurie 17 — I Lauronolic .... 23 — i Lignoceric .... 17 — t Linolenic .... 26^p Linolic .... 24— jp Linusic (Hexa-hydroxy-stearic) 11 — p Maleic . MaUc . Malonic Margaric Mesitonic Mesoxalic Methyl-hydroxy-glutario Myiistic W—d 8—d 9— c 17-0 19-g 7— c 8-/ 17— w Nondeoylic .... 17 — j Nonylenio .... 18— i Octa-hydroxy-margaric . 10 — o CEnanthyKo .... 17 — g Oleic 18— p Oxalic 9—6 Palmitic .... 17 — n Palmitolie . . . . 28— ra Pelargonic .... 17 — i Pentane-tri-carboxylio . . 4 — h Pimelic .... 9 — g Propiolic .... 28— c Propionic .... 17 — o Pyrotartario . . . 9 — a Pyroterebic .... 18—/ Bicinoleic .... 19—^ Boccellic .... 9—0 Saccharic Saccharinic . Sativic (Tetra-hydroxy- Sebacic Sorbic . Stearic Stearolic Suberic Suberonio . Succinic Tartaric Tartronic Teracrylio . Tetra-hydroxy-steario Tetrolic Therapic Tri-carballylic „ glycollic „ hydroxy-adipio „ „ stearic Undecolic TJndecylenic Undecylic . Valeric . . Xeronic . . s-/" 13-/ stearic) 13 — p 9-i 24—/ 17— p 28— p 9—h 18— h 9—d 7—d 8— c 18-gr 13—^ 28— d 27—0 11-/ 6-/ 14— p 28— k 18— k 17— fc . 17-e . 20— 7t 172 Table II.— SATURATED MONOBASIO CA„Os (Monatomio) Butyric Acid C^HeOa ; b.p. 162°-3 Monhydroxylie I • Dihydroxylio Trihydroxylie , Tetrahydroxylio Pentahydroxylic Hexaiydroxylio Octahydroxylic . C„H,„03 (Diatomic) ;3-Hydroxy-Butyric Aoid CiHgOa ; syrupy ; decomp. on heating O.H,.Oi O •■©-Q (Triatomie) Dihydroxy-Butyrio Aoid C^HsOi ; oily fluid ; deoomp. on heating OA.O5 (Tetratomio) Brythroglncmic (Brythritio) Aoid, O4H8O5 ; deliquescent crystalline C„H,„0, ^n^Sii-a^* (Diatomic) Succinic Acid C^HeOi ; m.p. 185° (Triatomie) Malic Acid, CtHeOs m.p. 100° (Tetratomic) Tartaric Aoid, CtHeOa m.p. 135° C'„Hon-207 (Pentatomic) Aposorbio (?) Acid ObHsOt ; m.p. 110° (Pentatomic) Meta-Sacoharinic Acid OgHiaOe; m.p. 141° (Hexatomio) Saccharic Acid, CoHioOg crystals, decomposing oh heating CnHo.O, (Hexatomio) Gluconic Acid CaHiaOT ; a syrupy Ugnid C„H,„Os vrllxllvllZ (Heptatomic) Linusio Aoid, CiaHjeOs ; m.p. 203° G^-B^O^oy !■ 1 lir.l Ixlliflll mmm \ (Nonatomio) Octahydroxy Margaric Acid, CiiHsjOio ; present in Cod Liver Oil that ' repeats ' ; derived horn Therapic Acid ALIPHATIC ACIDS 173 TnraABia TUIBABASIO Pbntababio HSXABASIO 0.H,..40, C„H, 0.H, (Triatomic) Trioarballylie Acid, CeHoOe ; m.p. 166° (Tetratomic) Iso-Allylene Tetra-Carboxylio Acid C5H4O8; Crystals ^nHjo-loOia (Pentatomio) Propargyl-Penta- Carboxylio Acid, CgHgOio not knowu in free state (Hexatomio) Buton-Hexa- Carboxylio Acid O10H10O12 ; m.p. 56°-5 0A..^0 (Tetratomic) Citric Acid OoHsOt ; m.p. 153° Ci.H2„_408 (Pentatomio) Hydroxy-Citric Acid, CgHgOe ; crystals C„H,„..0, (Hexatomio) Dihydroxy Iso- Oitrio Acid, CeHgOa properties not known 174 Table III.— UNSATURATED ALIPHATIC ACIDS Ethylene Acids Monobasic Dibasic Tbibasio G^2i,-20a i8-Crotonio Acid, CnHjj.iOi Maleic Acid, CtH^Oi m.p. 130° Ct^S^n-iOi Mono- hydroxylic CnH,„_^( /S-Hydroxy-Crotonic Acid, C^HgOa ; obtained as an Ether only Di- hydroxylic C.H,„.40, Dihydroxy-Maleio Acid C^HiOe ; crystals m.p. not ascertained CA..eO, Itaconic Acid, G5Hg04 m.p. 161° {vide fig. 765) Aconitic Acid, CsHgOg crystals, decomp. by beat Hydroxy-Itaconic Acid CsHeOs; oily liquid decomp. by heat Table IV.— UNSATURATED ALIPHATIC ACIDS Acetylene Acids MOirOBAEIO CnHsj.tOa Acetylene MonooarboxyUo Acid, PropioUc Acid, PropargyUc Acid, C3H2O2 ; m.p. 6° ; b.p. 144° CnHjj.oO^ Acetylene Dicarboxylic Acid, C4H2O4 ; melting at 175° under decomposition CoHon-aOo Diaoetylene Monocarboxylic Acii, OjHaOa ; explodes violently CnHso-loOt Diaoetylene Dicarboxylic Acid, CeHgO^ very explosive Tetraoetylene Dicarboxylic Acid, CioHjO^ FUNDAMENTAL ACIDS 175 SPBOIFIOATION" We can now turn our attention to the structure of a few members of the acids, some possessing a more general, others a more specific therapeutical interest. SATURATED ALIPHATIC AOID SERIES Monobasic Acids HYDROXYL-FREB (FUNDAMENTAL) ACIDS Th-e first we meet with is formed from methyl-alcohol (fig. 336, p. 69). Fia. 666 Formic acid, CH^Oa ; m.p. 8°'6, b.p. 100°'8 ; a powerful corrosive From ethyl-alcohol (fig. 337, p. 70) Fig. 667 Acetic acid, OaHiOa ; b.p. 118° In the cold it solidifies to large crystals melting at 17': glacial acetic acid. Vinegar contains 3-6 per cent, of this acid. Acetic acid forms with thyvnol (fig. 434, p. 97) and mercury a compound termed mercury thymol-acetate. It consists of two molecules bound together, not by linkage, but by something else, which we call molecular affinity, which, strictly, is but a cloak to cover our ignorance of the nature of the bond. One of these molecules is mercury with thymol on one side and an acetic acid group on the other, and the other molecule is mercury acetate (mercury, being in this case a dyad, binds two acetic acid-groups). Fig. 668 Meronry-thymol-aoetate ^^^ ^ i-Hg + (CaH302)2Hg = CieHa20,Hg2 {liierck's Benchte, Jan. 1893) A modern syphilis-remedy 176 OXTGEN-OOMPOUNDS The first molecule is, itself, strictly mercury-tliymol-acetate, bat this name was given to the whole compound before its structure was fully ascertained. From prima/ry joropyl^alcoTiol (fig. 338, p. 70) is derived ; Fio. 669 ? o o Propionic acid, CgHaOa ; b.p. 140° Prom the two primary hutyl-alcohols (vide normal and iso-butane, figs. 21 and 53, pp. 9 and 13) two acids are derivable : Normal butyric acid, C^HaOa ; b.p. 162''-5 Has a very unpleasant smell. The free acid is contained in the sweating of the feet and in Limburg cheese ; both have their odour from a percentage of this acid ; it is present as glyceride in butter (2 per cent.), whence, of course, its name. Fig. 671 Iso-but;rio acid, C4He02 ; b.p. 154° ; occurs in carob beans and Boman cbamomile oil Prom each of the four prima/ry pentyl-alcohols (p. 70) an acid has been obtained. Only one ot them has found a place in materia medica — that derived from inactive amyl-alcohol (fig. 344, p. 71). Fig. 672 Inactive valeric-, ordinary vaJerio-, iso-valerio-, iso-propyl-acetic-, delphinic-, phooenio-, or iso-butyl-formio acid, OsHijOj ; b.p. 176°'3 FUNDAMENTAL ACIDS 177 From eight possible primary liexyl-ahohols seven acids are known. One derived from normal hexane (fig. 62, p. 15) or its corresponding alcohol is Fia. 673 9 9 9 9 9 y®^ o o i 6 o Normal oapfoio acid, OoHiaOa ; b.p. 205° and from di-^methyl-fropyl-methcme (fig. 64, p. 15) is derived FiQ. 674 Iso-butyl-aoetic-acid, CeHijOa ; b.p. 200° Of the higher homologues may be mentioned Fia. 675 6 Q / Q iU-t^J,^.-^-^ Normal caprylic acid, CaHnjO^ ; b.p. 237° Pio. 676 8 (p / Q -®— O Normal capric acid, CioHjoOa ; b.p. 270° FiQ. 677 9 9 / O Undecylic acid, CnHaaOa ; m.p. 28° Fio. 678 10 -®— o Laurie acid, CiaHj^Oa ; m.p. 43°-6 Fig. 681 Fig. 679 12 o- Fio. 680 14 9 - 6 Myristio acid, CnHasOa ; m.p. SS'-S Palmitic acid, CioHjaOa ; m.p. 62° Fig. 682 15 9 -®— O Iso-palmitio acid, di-normal-heptyl-acetic acid ; CieHsjOa ; m.p. 26° Margario acid, CuHj^Oa ; m.p. 59°-8 178 Fig. 683 Stearic acid, C, gHajOa ; m.p. 69°-2 OXYGBN-OOMPOUNDS Fio. 684 iBO-stearic acid, di-octyl-acetic acid, CiaHaeOj ; m.p. 38°-5 Fia. 685 Arachidie acid, C20H40O2 ! m.p. 75° Fig. 686 Fig. 687 Fig. 688 O \ 6 Behenic acid, C22H4 m.p. Lignoceric acid, C^iBiiaO^ ; m.p. 80°'5 ; isomeric are: giugkolo acid, paraffinic and camauba acids Fig. 689 62 :^m- -® — o Cerotic acid, C27H54O2 ; m.p. 78° ; some give it the empirical formula G^g'S^^On, others say that cerotic acid consists of two different acids, one of which has the formula CjiHgaOa, m.p. 91° {Ber. ix. pp. 278, 1688) ; cerotic acid is (sometimes, but not always) the chief constituent of beeswax Theobromic acid, CatHugOj (?) ; m.p. 72° ; its existence has been doubted All of these acids occur in fats of some sort or other — caproic, caprylic, and capric acids in goat's milk, hence their names. Margaric acid occurs only in one fat, adipocire. The structures of the higher homologues have not been ascertained with any certainty, but their melting-points seem to indicate normal compounds. This criterion is regularly rising with the number of carbon-atoms in the normal acids, yet those with odd numbers and those with even numbers form two distinct series, of which the former have a lower melting-point than the others ; for instance Number of carbon-atoms Melting-point of even numbers . Melting-point of odd numbers . The melting-point of theobromic acid, 72°, would not indicate a normal, or perhaps not a pure compound. 8 9 10 11 12 13 14 15 16 17 18 16° 30° 43° 54° 62° 69° 12° 28° 40° 51° 60° HYDROXY -AOIDS These acids may be considered derivatives from di-acid alcohols (p. 76) by the oxidation of one of their hydroxy 1-links into carboxyl (through the intermediate aldehyde-formation), or they maybe regarded as derivatives from the fundamental acids, just described, by the substitution. of SATUEATBD HYDEOXYLIC ACIDS 179 hydroxyls. This latter view of the process will be adopted here, except in cases where a cor- responding fundamental acid has not been prepared. We will therefore illustrate, first, some of the acids derived by the introduction of one hydroxyl. Mono-hydroxy-acids In the first of the fundamental acids, /ormc acid (fig. 666, p. 175), a hydrogen-atom is replace- able by hydroxyl, and the hydroxy-acid produced would be Pio. 690 <^ Carbonic acid, CH2O3 ; hydroxy-formio acid The acid has not been isolated, probably on account of the two hydroxyls attached to the same carbon-atom (vide pp. 76 and 114), but is supposed to be present in aqueous solution. There is another circumstance remarkable with this acid. The carbonyl (00, fig. 527, p. 130) is patronising both hydroxyls, so that there are, in a sort of way, two carboxyls, each of the hydroxyls having a half share in the carbonyl, and this constitutes the acid a di-basic acid ; in point of fact, it is so, and this acid will therefore be mentioned amongst the di-basic acids (p. 184), although its correct place is here, when we look upon its structure as a combination of the group cwrboxyl with the alcoholic hyd/roxyl group, in which case the combination with the second base would not be a salt-formation proper, but an alcoholate. What we generally term carbonic acid is strictly carbon di-oxide (vide p. 184). Prom acetic acid (fig. 667, p. 175) by introduction of, or from glycol (fig. 364, p. 76) by oxidation of, a hydroxyl, glycollicacidis derived : I'la. 691 Glycollic acid, C2H4O3 ; m.p. 80° ; occurs in unripe grapes Next derivative is irom. propionic acid (fig. 669, p. 176). There is the choice of two places for the hydroxyl, consequently there are two acids Fia. 692 Q Fia. 693 t <^ -i>— o a-Hydroxy-propionic acid, inactive etliidene- (ethylidene-) lactic acid, nanceic-, thebolaotio acid, lactic acid, CaHeOg ; syrupy liquid ; forms anhydride when heated ; occurs in sour milk, in the gastric juice in dyspepsia ; used in diabetes, diphtheria, dyspepsia, diarrhoea, &c. /3-Hydroxy-jpropionio acid, ethylene-laotio acid, hydracrylio acid, CjHeOs ; syrupy liquid ; breaks up when heated Though according to our theory only two lactic acids are possible, as a matter of fact there are four. Three of them, including the above-mentioned a-hydroxy-propionic acid or inactive lactic N 2 180 OXYGEN-OOMPOUNDS acid, are chemically almost identical, but differ in optical behaviour. Inactive lactic acid, as it3 name implies, has no influence on the polarised light ; but there is one that turns the plane of light to the right termed active ethylidene lactic acid, pa/ra-lactic, or (because it is prepared from the juice of meat) sarco-lactic acid; and a third one (recently prepared from sugar by a bacillus) that turns the polarised light to the left, and therefore has the name of Isevo- lactic acid (Monatsh. xi. p. 545). The inactive acid is a combination of the two active compounds, neutralising each other's influence upon polarised light. There are, however, two ways in which this may be eflfected : either by the opposing activity of an equal number of molecules of the two acids, as in the inactive lactic acid, or in certain cases, to be subsequently mentioned, by the molecules exchanging halves of their chain (compare tartaric acid, p. 188). To make the cause of such physical differences intelligible by geometrical drawings (compare p. 50) would in some cases require another system of figures by which the facilities of perspicuity and comparability would be lost. I prefer therefore to reserve the explanation of these differences to the stereo-chemical theories, pp. 461 &c. There are four hydroxy-butyric acids, six hydroxy-valeric acids, and twelve hydroxy- caproi'c acids actually known. Of these it is unnecessary to specify but two, viz. leucic acid and a-methyl-iy-hydroxy-valeric acid, both hydroxylated caproi'c acids : Fio. 694 G— Leucic acid, a-hydroxy-caproic acid, CeHijOa ; m.p. 73° a-Metliyl-7-liydroxy-valeric acid, CaHigOs ; unstable Of the still higher homologues hydroxy-margaric and hydroxy-stearic acids may be mentioned. Two isomers of the former are said (Journ. pr. Gli. xxxvii. p. 53) to have been prepared, the hydroxyl in one of them being in a-, in the other in ly-position. The latter forms a lactone (vide p. 182). Di-hydroxy-acids As the first of these acids is derived from acetio acid, the two hydroxyls introduced must attach themselves to the same carbon-atom, there being no alternative : Fia. 696 Glyoxalic acid, glyoxylio acid, C2H4O4 ; crystals ; occurs in unripe fruit SATURATED HYDROXYLIO MONO-BASIC ACIDS 181 On account of the hydroxyls' proximate position, water is frequently eliminated with the formation of an acid of such structure : Fig. 697 This is an acid in which there is an aldehyde group (vide figs. 530 and 531, p. 130), and there- fore, properly, belonging to aldehyde acids, a class to be subsequently mentioned (p. 227). The acid assumes, probably, now one form, now another, according to circumstances. Another of the series is glyceric acid : Fio, 698 Glyceric acid, CsHeO^ ; syrupy fluid ; changes into anhydride by heat An isomeric acid in which the two hydroxyls are joined to the same (a-) carbon-atom is known, but only as chlorine-derivative. The acid itself cannot be isolated for reasons several times mentioned (see above). Of higher homologues there are di-hydroxy-stearic acid, CigHggO^, m.p. 136°-5, and di- hydroxy-jecoleic acid, CigHg^O^, m.p. 114-116°, the di-hydroxy acid of the recently discovered jecoleie acid in cod-liver oil. Tri-hydroxy-acids Besides the normal erythro-glucinic or erythritic acid, C^HjOj, tri-hydroxy-stearic acid, OigHggOg, m.p. 140°, and its stereo-isomer, iso-tri-hydroxy-stearic acid, m.p. 110°, derived from ricinoleic acid, and two others from ricin-elaJidio acid (vide p. 195) must be mentioned. Tetra-hydroxy-acids Three isomers are derived from hydroxy-caproic acids. One of them, from a-methyl 7-hydroxy- valeric acid (fig. 695, p. 180), is saccharinic acid (not to be confounded with the di-hasiQ saccharic add, fig. 732, p.' 188) : Fia. 699 (Grluco-) saccharinic acid, CeHjaOa (Beilst. i. p. 667) 182 OXYGEN-COMPOUNDS When heated, a molecule of water is eliminated, formed from the carboxyl's hydroxyl and the hydroxyl's hydrogen-atom of the 7-link ; and the chain tending forms a ring in order to unite the two valencies disengaged by the departure of the hydroxyl and the hydrogen-atom. Pio. 700 Fia. 701 — O ^ — #-0 •o Saccharin, CgHioOs ; m.p. 160° ; bitter taste Must not be confounded with the fashionable saccharine (vide fig. 1308, p. 368), which is so exceedingly sweet. The isomeric acids form corresponding saccharins. Many of the hydroxy-acids, particularly those with their hydroxyl in 7-position, like the above, have a great tendency to form a similar ring at that end of the chain. The product of this intra- molecular ring-formation in an acid is termed a lactone or an intra-molecular anhydride. Some o- and supposed j8-lactones are also. known, but as a rule the hydroxyl in /3-hydroxy-acids does not take the hydrogen-atom from carboxyl, but from the link at the other side of it, creating a double bond between the two links : F18. 703 ;3-Hydroxy-propionic acid — water Acrylic acid + water Authorities do not agree upon the behaviour of a-hydroxy-acids. One opinion is that they form a lactone analogous to the ghcides (vide p. 116) Fio. 704 Fio. 706 O— ®— O GlyooUic acid (fig. 691, p. 179) Glycolide, CjHaOa ; m.p. 220° SATURATED HYDROXYLIO MONO-BASIC ACIDS Fio. 707 Fio. 708 183 6 a Ethylidene-lactio acid \-Pa 6 © Laotide, C3H4O2 ; m.p. 125° It is, however, more probable that neither glycolide nor lactide are the products of intra- molecular anhydration, but that each of them is composed of two or more molecules of the acids, and therefore are regular anhydrides. As such they will be subsequently mentioned (vide p. 257). As regards glycolide see 5er.,xxv. p. 3511, and xxvi. p. 262. After this little deviation from our straight path we can finish our discussion of the tetra- hydroxy-acids by mentioning normal tetra-hydroxy-stearic acid or sativic acid, CigHggOg, m.p. 173°. Sativic acid may be converted into stearic acid; its structure is therefore normal, but there is no evidence conclusively showing the exact positions of the hydroxyls. Penta-hydroxy- acid s We know several isomeric compounds of six carbon-atoms belonging to this series : gluconic, para-gluconic, lactonic or galactonic, mannonic, glucogenic (?) acids. Most of them have a normal structure : Fio. 709 Those which are derived from sugars by oxidation (gluconic, galactonic, mannonic acids) are re- converted into the original sugar by reduction of their lactones {Ber. xxii. p. 2204, and xxiii. p. 930). The isomeric differences are most probably the various arrangements of the hydroxyls, some standing upright, others hanging down as demonstrated of the grape-sugar group (p. 153), these acids being obtained from the sugars. We cannot tell yet, with any degree of certainty, whether the hydroxyls point upwards or downwards; therefore they are in this treatise handled arbitrarily as the convenience of illustrating the progress of a process may require. Hexa-hydroxy-acids Besides the little known triglycollic (CgHijOg) and carbo-gluconic (CjHj^Og) acids (the first of which may perhaps belong to quite a different series of acids, and the second is only probably one of this series), we have hexa-hydroxy-stearic acids termed linusic acid, OigHjgOs, m.p. 204°, and iso-linusic acid, CigHggOj, m.p. 174° (Monatsh. viii. p. 159 and ix. p. 180), obtained from linolenic and iso-linolenic acids (p. 198). By the structure of these acids the structure of the hexa-hydroxy-acids is determined. 184 OXYGBN-OOMPOUNDS O Gta-hy droxy-acids The only known member of this series is ocfca-hydroxy-margaric acid. It is derived from tlierapie acid (vide p. 198), and causes the well-known eructations after taking cod-liver oil. It has not been isolated. No acids with more than eight hydroxyls are known, and we will therefore pass on to describe the Di-basic Acids of the saturated series. They are characterised by the presence of two carboxyls in the chain. HYDBOXYL-FREE ACIDS The first acid is formed {rom formic acid (fig. 666, p. 175), and is already referred to (p. 179) under the mono-basic mono-hydroxy-acids, viz. carbonic acid. From reasons there stated it is referred to this series, both its hydrogen-atoms being easily replaceable by basic bodies. It is not known in the free state, decomposing into water and carbon di-oxide (generally called carbonic acid) Pig. 710 Fig. 711 •t^G- — #— ^ *i ©.■ Carbonic acid Water + Carbon di-ozide From acetic acid (fig. 667, p. 175) is derivable Fig. 712 Oxalic acid, C2H2O4 ; m.p. 189°'5 ; crystals, subliming upon cautious, decomposing upon rapid heating ; poisonous ; occurs in many plants, oxaUs, rwmex, rhubarb, &c., mostly as salts ; some urinary calculi consist of the calcium or ammonium salt ; human urine contains, probably always, minute quantities, in some diseases more. Commercial salt of sorrel is a potassium oxalate (in which potassium has replaced one of the hydrogen atoms) in combinaticn with another molecule of oxalic acid Fvom propionic acid (fig. 669, p. 176) is derivable Malonic acid, C3H^04 ; crystals ; m.p. 134° ; occurs in beet-root SATURATED DI-BASTC ACIDS 185 From the butyric acids (figs. 670 and 671, p. 176) two corresponding di-basic acids are derived : FiO, 714 Fig. 715 <^ i <^ (6 6 Common snccinic- or ethylene-suooinio acid, symmetrical ethane-di-oarboxylic acid, C^HjOi ; m.p. 185° Iso-sucoinio- or ethylidene-suocinic acid, C^HjOi ; m.p. 130° The two acids behave differently when heated. The first forms a lactone, the other breaks up into propionic acid and carbon di-oxide (carbonic acid). The processes will be understood without further display if we refer to the formation of lactones (p. 182). From succinic acid ; Fig. 716 From iso-succinio acid : Fig. 717 Fig. 718 o e-H> — © + G- -#—0 or o 9 -®— o Succinic anhydride (lactone) m.p. 120° Carbon di-oxide Propionic acid From each of the four valeric acids a di-basic acid may be derived and has been prepared. Two of these are Fig. 719 Fig. 720 O— ®- ^ Q p Q — <»— O -#— o GHutaric acid, normal pyrotartario acid, CsHgOi; m.p. 97°'5 Pyrotartaric aoid, methyl- succinic acid, CsHgO^ ; m.p. 112° Amongst the higher homologues derivable from ca^roic, oenanthylic, cofprylic, pelargonic, and ca/pric acids, or their isomers, the undermentioned have more or less interest. Fig. 722 Fig. 721 O— @- .<:>/I ^<^ -o Adipic acid, CuHioO^ ; m.p. 149° ; eight isomeric acids besides are known 6 Pimelic aoid, C7H12O4I m.p. iOB° ; nine other isomers are known, including the normal 186 Fig. 723 Pentyl-malonio acid, CsHi^O^ ; m.p. 82° ; amongst its five isomers is suberic acid (m.p. 141°), probably the normal acid OXYGEN-COMPOUNDS Fia. 724 #— K) O—®- < ^^ n<^ -® — o Normal azelaic acid, CgHjeO^ ; m.p. 107° ; azelaio or lepargylio acid (m.p. 106°) is the only isomer known, but its structure has not been ascertained Fio. 725 Sebaoio acid, CioHigOi ; m.p. 133° (comp. p. 194) As regards melting-point these acids show the same behaviour as the fundamental acids (vide p. 178), with the remarkable exception that even numbers form a descending scale, whereas odd numbers, with the exception of the first, form an ascending scale : Number of carbon-atoms ..23 Melting-point of even numbers . 189°-5 Melting point of odd numbers . 134^ 4 5 6 185° 149° 97°-5 7 8 9 10 141° 133° 103° 107° HYDEOXY-AOIDS Mono-liydroxy-acids By introducing a hydroxyl into malomic acid (fig. 713, p. 184), we have Fia. 726 o-#- Tartionic acid, hydroxy-malonic acid, C3H4O5 ; m.p. 186°, breaking up at that temperature By the same process succinic acid (fig. 714, p. 185) becomes Fio. 727 ? Malic or hydroxy-succinic acid, CiHeOj ; m.p. 100° ; occurs widely distributed in the vegetable world ; recommended as an effective expectorant Besides an isomer formed from iso-succinic acid (fig. 716, p. 185), m.p. 178° (decomp.) there are three optically different malic acids, all having the same linking structure. Their structural differences will be explained by the stereo-chemical theory [vide pp. 461 &c.). SATURATED HYDROXYLIO DI-BASIC AOIDS 187 Prom glutario add (fig. 719, p. 185) : Fia. 728 ? o-Hydroxy-glutario acid, CoHsOg ; m.p. 72° Amongst its eight isomers are hydroxy-pyro-tcvrtwriG, itwmaUc, and dtrcumalic acids; they are all structural isomers, besides which there are stereo-isomers. Di-hydroxy-acids When we add another hydroxyl to tartronic acid (fig. 726, p. 186) we have no other carbon- atom to attach it to than the one already charged with a hydroxyl ; this is, as we know, an awkward position for a carbon-atom — a situation it tries to get out of as soon as there is an opportunity by discharging one of the hydroxyls in form of water. The acid thus produced, mesoxalic acid, has therefore probably two forms of which it makes use, as circumstances necessitate, in analogy to glyoxalic acid mentioned on p. 180. Fia. 729 Fio. 730 -#— o or Mesoxalic acid, CgH^Og or CaH^O^ ; m.p. 115° The second structure belongs to ketone acids (vide p. 227). By introducing two hydroxyls into sucdnic acid (fig. 714, p. 185), or a second one into malic acid (fig. 727, p. 186), we get tartaric acid. Fia. 731 #— O Tartaric acid, C4H5O There are four acids of the above structure, almost identical in their chemical properties, but there are optical difierences in three of thern, and between the two optically alike there are some minor chemical differences : one is dextro-, another Isevo-rotatory, and the other two are inactive. The first is termed dextro-tartaric acid, the second Isevo-tartaric acid, and the others racemic acid and meso-tartaric acid respectively. The difference between dextro- and Isevo-tartaric acids is easily explicable by the stereo- chemical theory, as in similar cases mentioned before (vide malic acid, p. 186), and will be 188 OXYGEN-COMPOUNDS subsequently more fully discussed. In racemic acid there are equal numbers of molecules of each of these two acids present, and every molecule in meso-tartaric acid is composed of half a molecule dextro- and half a molecule laevo-tartaric acid. In our figures these isomerisms may be expressed by making one of the hydroxyls hang down in dextro-tartaric acid ; reverse the positions of both hydroxyls in the l^vo-compound, and meso-tartaric acid would be represented by the preceding fig. 731 (vide figs. 1579 to 1581, p. 464). Tri- and tetra-hydroxy-aclds There are no tri-hydroxy-acids of sufiBcient interest; but of tetra-hydroxy-acids, saccharic and mucic acids attract our attention. They are normal acids, and their only difierence of structure consists in the positions of the hydroxyls, as explained under the grape sugar group, p. 153, and the mono-basic-penta-hydroxy-acids, p. 183, and the tartaric acids above. Accordingly two of the acids may be represented thus (Ber. xxiv. p. 2685) : Fio. 732 Fia. 733 Saeohario acid, CeHjoOa ; m.p. 130-132° (saccharinio acid is a difierent compound, vide fig. 699, p. 181) Mucic acid, CgHioOa ; m.p. 213° decomp. Mucic acid is optically inactive; but there are two optically difierent, besides an inactive, saccharic acids ; one of the active acids may be represented as above, the other by reversing the positions of all the hydroxyls ; the inactive acid is a mixture of an equal number of molecules of each of the two others, and mucic acid is composed of half a molecule each of the two active forms, all bearing the same relation to each other as the tartaric acids ; another series of isomeric acids, OgHjgOg, mutually related in exactly the same way, are the three manno-saccharic-acids and allo-mucicacid, the latter corresponding to mucic and meso-tartaric acids (for stereo-chemical explanation vide p. 464). Tri-basic Acids There are but few tri-basic acids known, and, of them only three to be mentioned here, one hydroxylrfree : tri-carballylic acid; one mono-hydroxy-acid : citric acid; and one di-hydroxy: desoxalic acid. Fio. 734 ©— !>—- -(D— o Tri-carballylic acid, CeHgOe ; m.p. 166° SATUEATED HYDEOXYLIO POLY-BASIC ACIDS 189 G — ©- Citrio aoid, CeUgO, j m.p. 153° ; occurs in lemon and other sour fruits, in tobacco, in milk, in the sap of the vine (only in the spring) ; can be synthetically prepared from glycerin Fio. 736 #— O Desoxalfc aoid, CsHeOa ; easily decomposed on heating Tetra-, Penta-, and Hexa-basic Acids None of thetn occur in nature. The examples set out in Table II., p. 173, are sufficient for our purpose. UITSATURATED ALIPHATIC ACID SERIES BTHYLJENE A GIBS MONO-BTHYLENE ACIDS Mono-basic Acids HYDEOXYL-FEEE. OLEIC SERIES These acids may be considered derived from the fandamental saturated acids by the removal of two hydrogen-atoms, and may be reconverted to them by restoring the two hydrogen-atoms removed. In them two carbon-atoms are joined by a double bond ; consequently a third atom is required in order to form the carboxyl, and the simplest compound in the series must therefore consist of three 190 OXYGEN-COMPOUNDS carbon-atoms, and may be considered as derived from prapionie acid (see Table la, p. 171, and fig. 669, p. 176) by the removal of two bydrogen-atoms. G- FiG. 737 Fio. 738 u 6 6 Propionic acid Acrylic acid, CaH^Oa ; b.p. 140° ; very similar to propionic acid, to which it may be converted by reinstating the two hydrogen atoms removed From butyric acids (figs. 670 and 671, p. 176) it is possible to derive three acids of this series, two from the normal acid by removing difierent pairs of hydrogen and one from the iso-acid ; in addition an acid is known, which has the same geometrical structure as one of the derivatives from the normal compound, but differs in stereometrical respect. G- FiG. 739 {}C> 44 I I Normal butyric acid Fig. 740 1. a-Crotonic acid, C^HeOj ; m.p. 72° 2. Stereo-isomer : iso-orotonic acid, liquid- (or erroneously /3-) crotonic acid ; b.p. 172° ; changes on heating into orotonic acid 6 6 Normal butyric acid Fia. 742 9 tlJ^ 6 Tinyl-acetio acid, the true jS-orotouic acid, C^HgO, {Ber. xvi. p. 2592; Ann. eolxvi. p. 358). This was formerly believed to be the constitution of iso-crotonio acid, hence its designation as ;3-crotonic acid 6 6 i J. Iso-butyric acid Methacrylic acid, CiHeOj ; m.p. 16°, b.p. 160° in the oil of chamomile From one of the isomers of normal valeric acid (methyl-ethyl-acetic acid) occurring in the fruits of angelica a/rchangelica, two acids originate, which stand in the same relation to each other UNSATUEATED MONO-BASIO ACIDS 191 as crotonic- and iso-crotonic acid, viz. angelic acid and tiglio acid; their joint structure is represented by 1. Angelio acid, OsHsOa ; m-p- 45° ; is found in the angelica root and in Eoman chamomile oil 2. Tiglio aoid, CjHaOa ; m.p. 64° ; occurs in oroton oil as glyceride, and in Eoman chamomile oil Only few of the higher homologues need mentioning, their exact constitution not being known with certainty. All the acids contained in natural fats have a straight chain as far as has been ascertained, but the difficulty is to locate the double bond. When we break up a doubly-linked chain we generally suppose, as stated before, that it parts at the double bond ; therefore when we ascertain what the fragments are, the position of the double bond is a matter of course ; still there are undoubted exceptions. The first higher homologue we have to mention is LI fiG. 746 8 Undeoylenio aoid, CnH^oOa ; m.p. 24°*6 Judging from its derivation from ricinoleic add {vide fig. 760, p. 194), the structure, which is a strictly normal one (comp. p. 20), should be correct. Of homologues with the following structure Fig. 747 1 11] u <^ . 6 \ 6 #— O there are three acids, of which two are stereo-isomeric ; the isomeric difference of the third is not known: 1. Hypogseic acid, Ci^B.^fi^, m.p. 33°, occurs in earth-nut oil. When distilled yields sebacic acid (fig. 725, p. 186). 2. Grasidinic acid, Gi^R-^fi^, m.p. 39°, is a stereo-isomer of hypogseic acid, and stands to that acid in the same relation as crotonic to iso-crotonic, angelic to tiglic acid. 8. Physetoleic acid, OigHggOj, m.p. 30°, isfoundin spermaceti oil from the sperm-whale. Does not yield sebacic acid. Assuming the rule to be correct that compounds with double bonds break up into smaller pieces 192 OXYGEN-COMPOUNDS at the place or places where there are such bonds, hypogEeic acid, yielding sebacic acid (OmHigOJ should, as regards the double bond, have such structure : Fig. 748 Hypogseio acid Doubly linked acids with seventeen carbon-atoms are unknown, but with eighteen we know of oleic acid and its isomers, elaidic acid and iso-olei'c acid. Oleic acid and elaidic acid have one structure which has been differently interpreted as either one or other of these ' Fig. 749 a Pig. 749 b 13 7 7 9 Li, I. or 6/ o Joum. pr. Ch, xzxvii. p. 6 . Oleic acid, CieHg^Oj, solidifies at 4°, melts again at 14°. Its behaviour towards phenyl-hydrazine confirms the supposition that the double bond is not close to the carboxyl {Ber. xxvi. p. 118). It is present, joined to glycerin, in nearly all fats or fatty oils, particularly in olive- and almond-oil. 2. Stereo-isomer : elaidic acid, G^^^JH^, m.p. 45°, does not occur in nature, but is prepared from oleic acid, like gseidinic acid from hypogseio acid, and is a stereo-isomer of oleic acid analogous to the other stereo-isomeric acids mentioned. Fig. 750 LiO. # — o Iso-oleic acid, CigHa^Oa, m.p. 44°, has, according to the first of the above authorities, this structure, the double bond shifting from j3- to a-position There are two isomers with nineteen carbon-atoms, viz. dceglic acid and jecoleic acid. We know scarcely anything of doeglic acid beyond that it is yellow, solidifies on cooling exactly like most other fatty oils. Jecoleic acid is so recently discovered, as one of the essential constituents of cod-liver oil, that not much information is to be had about it ; both because it easily breaks up and because its di-hydroxy-acid {vide p. 181) has a lower melting-point than its lower homologue di-hydroxy-stearic acid, it is most likely an iso-compound as regards its double bond. On account of its easy decomposition it has not yet been prepared in the free state. Prom this fact it may perhaps be concluded that dcEglic acid and jecoleic acid are isomeric, and not identical. A normal acid of this division would have the following structure : ^ Fig. 751 ' The stmctures of stearolic acid, p. 199, and stearoxylic acid, p. 200, must be altered accordingly. UNSATURATED MONO-BASIO ACIDS 193 and an iso-acid would be (x + y=15) Jeooleio acid, CigHagOj It is not likely that jecolei'c acid has side-chains, as no acid derived from natural fats has as yet been found to have any; they have all, without exception, straight chains, as already mentioned. The last of these ethylene-acids has twenty-two carbon-atoms, and exists in two stereo-isomeric modifications: erucic and brassidic acids. They are so far interestiug compounds as that the correctness of applying the stereo-chemical theory to these isomers has recently been conclusively proved by some elegant experimental researches (Ber. xxiv. p. 4120). Supposing thedouble bond to take up the position between the 13th and 14th carbon atom (Ber. xxvi. p. 1867), their structural formula may be rendered thus : Fio. 753 <© — O 1. Bruoio acid, Ca^H^jOs ; m.p. 34° ; occurs in rape seed oil and mustard oil 2. Brassidic or eruoidio acid, CjaH^jOa ; m.p. 56° All unsaturated ethylene-acids are converted into corresponding fundamental acids by addition of two hydrogen-atoms to the double bond, erucic-, to behenic acid, oleic-, to stearic acid, angelic-, to valeric acid, &c. ; e.g. Fio. 754 Erucic acid + two hydrogen atoms Behenic acid 194 OXYGEN-COMPOUNDS HYDROXY- ACIDS Only mono-hydroxy-acids of the mono-basic ethylene series are known ; there are but few of them, and the only one of interest for our purpose is ricinoleic acid, because it affords a good opportunity for demonstrating how conclusions are drawn as to the structure of doubly linked compounds, and how a clue to the structure of other compounds may be found at the same time." Ricinoleic acid breaks up, on heating with alkalies, into two fragments : a secondary caproyl- alcohol (methyl-hexyl-cmrbinoV) and sehacic acid (fig. 725, p. 186) (a hydrogen molecule being provided for by the alkali-hydrate) : Fig. 757 Secondary oaproyl-alcohol Sebaoio acid That is strong evidence of this being the structure of ricinoleic acid : Fio. 758 ^ 5 UjjI .^D — o (Ber. xxi. p. 2734) BH34O3 ; oily liquid, decomposing on heating; occurs joined to glycerin in castor oil Further, it has been experimentally proved that ricinoleic acid is converted into stearic acid by addition of two hydrogen-atoms and by substitution of the hydroxyl by a third hydrogen-atom, and we know that stearic acid is a normal compound. From the first of these reactions, the addition of two hydrogen-atoms, we conclude the presence of a double bond, and from the formation of normal stearic acid we conclude that sebacic acid also must have a normal structure, and the secondary caproyl-alcohol a straight chain. This structure of ricinoleic acid is confirmed by distilling it under diminished pressure, when it breaks up into oenanthol (fig. 544, p. 132) and undecylenic acid (fig. 746, p. 191 ; £er. x. p. 2035) : Fig. 759 Fig. 760 \, 4- CEnantliol Unde"cylenic acid TTNSATUEATED HYDEOXTLIO POLY-BASIO AOIDS 195 consequently the struoture ofricinole'ic acid should be Fig. 761 Eicinoleio acid If the conclusions are correct, it follows that oenanthol is a normal structure, and that undecylenic acid should have the structure given at p. 191. However, it is just possible, though not probable, that an intramolecular re-arrangement occurs analogous to what takes place in the acetylenes {vide p. 40). From ricinoleic acid a stereo-isomeric acid, analogous to iso-crotonic, tiglic, geeidinic, elaidic, and brassidic acids, is derived. It is termed ricinelaidic acid. When hydroxyls act upon ricinoleic acid two of them add themselves to the double bond, changing it into a single bond, and the acid becomes then a stearic acid with three hydroxyls. They can attach themselves in two stereo-different ways ; therefore there are two different tri-hydroxy- stearic acids to be derived from ricinoleic acid : this gave rise to a belief in the existence of two different ricinoleic acids — ricinolic and ricinisolic acids (Monatsh. ix. 1888, p. 475). Stereo- chemical considerations, however, are quite capable of explaining the formation of two different hydroxy-acids from one and the same acid (Monatsh. xiii. 1892, p. 326). From ricinelaidic acid also two hydroxy-acids are obtainable; consequently four tri-hydroxy-stearic acids exist {vide p. 181). Di-basic Acids are characterised by two carboxyls and a double bond. The lowest number of carbon-atoms forming one of these acids must be four ; consequently it is to butane, by,tyl alcohol, or butyric acid we shall look for the formation of the first of them, of which there are two stereo-isomers : Fig. 762 1. Fumario aoid, O4H4O4 ; sublimes at 200° without melting, at the same time being converted partly into 2. Maleio aoid, O4H4O4 ; m.p. 130°, which can again be converted into fumaric aoid -^ Fumaric acid occurs in Lichen islandicus, Fumaria officinalis, and several other plants and fungi ; maleic acid does not occur in nature. They are practically convertible into succinic, malic, tartaric, &c., acids by judiciously introducing hydrogen-atoms and hydroxyls, and into butyric acid by methyl-substitution of carboxyl, thus going through the whole column d on Table I., pp. 171a, 171&. Amongst the eight isomers of the next acid, derivable from valeric acid, we again meet with two stereo-isomeric acids : Fig. 763 9 Q — ®- Ll^ 1. Citraconic acid, CjHeO^ ; m.p. 80° ; and 2. Mesaconic aoid, C5H0O4 ; m.p. 202° o 2 196 Another isomer is OXYGEN-COMPOUNDS Via. 764 Itaconic acid, CsHgOi ; m.p. 161° The molecular refraction (vide p. 144) of the acid points to the absence of any double binding in it, and another structure has therefore been suggested (Jown. pr. Oh. ii. 31, p, 348 ; Beilst, i. p. 621), founded upon the tri-methylene structure (fig. 112, p. 24) : Fig. 765 Another structure of itaconic acid There is, however, an acid, tri-methylene di-carboxyHc acid, of certainly this very structure but of properties widely different ; therefore it is not probable that itaconic acid is thus correctly represented. The other acids of this series do not require our attention, neither do the hydroxy-compounds. Tri-basic Acids Only one is known with certainty, viz. aconitic acid : Fig. 766 Aconitic acid, CeHaOe ; m.p. 186° ; occurs in several acomtum species, sugar-cane, beet-root, &o. Aceconitic, iso-aconitic, and pseudo-aconitic acids are believed to be isomers, but their structures have not been ascertained. POLT-ETHYLBNE ACIDS 197 DT-ETHYLENB AOIDS But few di-ethylene- acids are known. Sorbic acid is one of them, and its structure may be thus illustrated: Fig. 766 A o— LJ LJ<^ ■#— o Sorbic acid, CeHgO^ ; m.p. 131°'5 ; occurs in unripe mountain-ash berries Di-allyl-acetic acid is another with the following structure: Pi8. 766 b LJ n I i-i Di-allyl-aoetio acid, CsHiaOa ; b.p. 222° ; a laboratory product Blaeo-margaric acid has not. been much examined as to its structure ; it may, in a general way, be represented by Fig. 767 y 0- \i\\u{\\\xm 6 \ o -#— x + y + z = ll. Flseo-margaric acid, CX7H30O2 ; m.p. 4S° ; occurs joined to glycerin in oil from the seeds oi Elmicocca vernicia An isomer, elaeolicacid, is also found in that oil, and another isomer, elseo-stearic acid (m.p. 71°), is formed from elcBO-margario acid on exposure to light. Some authorities suppose a triple bond in elsso-margaric acid, and call it margarolic acid. Linoleic acid used to be the name of the acid bound to glycerin in linseed oil, but recently it has been found to consist of several acids (Monatsh. viii. p. 147 seq.) : linolic acid, C^^TI^fi^, linolenic acid, OjgHjgOj, and its isomer, iso-linolenic acid. 198 OXY GEN-COMPOUNDS The fii'st of them belongs to tMs series : x + y + s = 12; y cannot be = 0. Linolio acid, CiaHajOa Some light has been thrown upon the constitution of this oil. We know there are no side-chains, because it may be converted into stearic acid (fig. 683, p. 178), and the double bonds are separated by at least one methylene (fig. 35, p. 11), and therefore y cannot be = 0. On oxidation it yields sativic acid (p. 183). TRI-BTHTLBNB AOIDS The only ones known are linolenic acid and its isomer, iso-linolenic acid, expressed in a general formula thus : Pig. 769 t ui]un\uii\uii w + x + y + z = 10; w and z may be = 0, but x and y probably not. Linolenio acid, OigHaoOa By oxidation it is converted into hexa-hydroxy-stearic (linusic) acid. Nothing is known of the structure of iso-linolenic acid. It has not been isolated ; it forms on oxidation an iso-hexa-hy droxy-stearic acid(iso-linusic acid). TBTRA-ETHTLENE ACID Therapic acid, just discovered in cod-liver oil by Heyerdahl, is the only known acid of this class. It has a straight chain and four double bindings, probably not close to the carboxyl; beyond this nothing is known of their position. It is only the bromine addition-product that it has been possible to prepare, the free acid being so susceptible of all reactions brought to bear upon it in order to isolate it that it at once spUts up into a mixture of decomposition products. Prom its bromine-addition product we can conclude that the structure must be represented thus, when we remember that acids from natural fats have straight chains without any side-biikiiigs : Fio. 770 O- nijgujmi idu in v + w + x + y + z = l. Tberapic acid, Ci^HjeOa As v + m + x + y + z being =7, therapic acid has probably a structure in which z = S and y^w + x + y=4<, if not a strictly normal structure : H20 = ( = 0=)3=OH— (CH2)iiC02H. It is also remarkable as belonging, with its seventeen carbon-atoms, to the margaric acid family, which has so very few representatives (see Table I.) to boast of. This is the last of the ethyleue-acid series. ACETYLENE ACIDS 199 AGHTYLEKE ACIDS MONO-ACETYLENE ACIDS Monobasic These acids are characterised by a triple bond ; the place in the chains, especially the longer ones, has been fully ascertained in a few instances only. In other cases I have uniformly placed it next to carboxyl, as it must be put somewhere. The acids are not many, and only interesting from a theoretical point of view. The first is -derivable frova propionic acid (fig. 669, p. 176) by removal of four hydrog&n-atoms : Fia. 771 From hutyric acid : From undecylio acid : Propiolio (propargylic) aeid, C3H2O2 ; b.p. 144° Fig. 772 G- Tetrolie acid, C4H4O2 ; m.p. 76°-o Fig. 774 Undeoolio acid, CuHigOa ; m.p. 59°'5 Amongst the higher homologues are Fia. 775 Palmitolio acid, CibHjbOj ; m.p. 42° Fig. 776 Stearolio acid, CiaHjjOa ; m.p. 48° 200 OXYGEN-COMPOUNDS Fia. 777 Behenolio acid, Ca^HioOa ; m.p. 57°-5 {Ber. xxvi. p. 1867) When acetylene acids are oxidised, hydroxy-acids are not formed because the tydroxyls would have to join the same carbon-atom, and, as we know, such compounds are very unstable, and can only exist under specially favourable circumstances ; however oxy-acids (but not hydroxy-acids) are formed, each oxygen seizing both valencies of each carbon-atom. Therefore when, e.g. stearolic acid is oxidised, an acid is formed possessing this structure (Anrud. cxl. p. 63) : Fig. 778 Stearoxylic acid, CieHsaOi ; m.p. 86° The structure of di-acetylene-mono-basic acids and of mono-, di-, andtetra-acetylene- di-basic acids are already given in Table IV. p. 174. ACID -RADICALS Frequent use being made ia the nomenclature, of radicals of acids, illustrated representations of those often met with may be acceptable : they are formed by removing hydroxyl from carboxyl, produciag mono-valent radicals from mono-basic acids, and di-valent radicals from di-basic acids. In the case of hydroxy-acids, radicals are sometimes formed by removing alcohol-hydroxyls besides the hydroxyl in the carboxyl group, poly-valent radicals ensuing according to the number of hydroxyls removed. An enormous number of radicals may be formed conformably to these rules ; therefore I can select but those most useful to know. Prom fundamental acids by removing hydroxyl from carboxyl, mono-valent radicals are derived : {■ \ Carboxyl, COjH Carbonyl, 00 Fia. 779 Pormyl, CHO Acetyl, C2H3O Fia. 781 ? l^ Propionyl, CsHjO Fio. 782 ^ Butyryl, O^HjO ¥rom hydroxy-acids of fundamental acids, di-valent radicals are formed by further removal of an alcohol hydroxyl : Pio. 783 ACID-EADIOALS Fig. 784 201 yi- oyl o ^ Fig. 785 GlyooUyl, CjH^O Fig. 786 o-Laotyl, O3H4O j8-Laotyl, C3H4O Pig. 787 I I<^, 9 ? ? ? /®s. Divalent 7-butyryl, C^HeO a d Divalent S-valeryl, CsHgO From di-basic acids, by removing the hydroxyls from both carboxyls, di-valent radicals : Fig. 788 Fig. 789 9 L^ Fig. 790 K> Oxalyl, C2O2 Malonyl, C3H2O2 and from three carboxyls, tri-valent radicals : d Succinyl, OJitflx ^ Fig. 791 9^ : Pig. 798 G—®— O O^ — ®— O Two molecules of carbon-dioxide two molecules of water Our resources of forming new compounds without invoking the assistance of other elements are, however, not exhausted ; on the contrary, we have hitherto, as it were, only been pre- paring material for the real work to begin, and it is not solely the genius of man that performs the work, for even Nature herself takes a share in it, though, it must be admitted, only a com- paratively small one. Human work is in this instance more thorough, though Nature is more skilful, and can produce things in comparison to which ours often are but clumsy imitations, and frequently not even that. Our way of performing the work is very much in the cooking style : a little of this, a little of that, a sprinkling of seasoning, and voild a new dish. Thus we take the end of one thing and the beginning of another, sometimes two beginnings or two ends, or a middle part of a third is put between ; here a little oxygen, carbonyl, or hydroxyl for seasoning, there a little hydrogen and such like for sweetening. Order must be kept in such a motley medley, and therefore we avail ourselves of our old expedient, classification. An acid may be looked upon as consisting of two parts : carboxyl indicating the genus, and the rest indicating the species. To either of these or to both simultaneously members of all the classes of compounds discussed up to now, may be joined by separation of a molecule of water, if the union. is efiected through a hydroxyl; but otherwise by abstraction of our usual pair of hydrogen- atoms. In this way new classes of bodies may be created dependent upon the sort of compounds joined, and upon where they are joined, i.e. whether the union takes place at the carboxyl end or at the 206 OXYGEN-COMPOUNDS opposite — we will call it alkyl — end of the acid, and also which end (in case of existing difference) the substituting body offers for the joining. Accordingly the following new classes of compounds may be formed : A. Gyclo-aeids : By joining the alkyl-part of an, acid to the hydroxy 1- carbon of a phenol ; or, in the case of a hydroxy-acid, by joining one of the hydroxyl-carbons to a cyclo-hydrocarbon. B. Aldehyde-acids: By joining the carboxyl-part of formic acid (or the alkyl-part of an aldehyde) to the alkyl-part of an acid. 0. Ketone-aoids : By joining the aldehyde-part of formic acid (or any other aldehyde-acid, or the alkyl-part of another acid) to the carboxyl-part of a second acid. D. Ketone-aldehydes : By joining the carboxyl-part of an acid (aldehyde-acids excepted) to the alkyl-part of an aldehyde. E. GoTYvpound ethers ; 1, neutral: By joining the carboxyl-part of a monobasic acid (or all the carboxyl-parts of a polybasic acid) to an alcoholic or phenolic carbon of another compound ; 2, acid: By joining one or more, but not all, carboxyl-parts of a polybasic acid to an alcoholic or phenolic carbon of another compound. P. Ether-acids : By joining a hydroxy-acid and an alcohol or phenol through their alcoholic or phenolic carbons, and the carboxylic hydroxyl. G. Acid-anhydrides : By joining the carboxyl-parts of two acids. The formation of these compounds will be easily understood by the following illustrated schedule : MUTUAL COMBINATIONS; CLASSIFICATION 207 A A Cyclo-aoids Hydrocarbon or Phenol and Acid vide p. 208 Benzene + Glycollio Acid Phenol + Acetic Acid ' Phenyl — Acetic Acid B B C C D D Aldehyde-aoids Formic Acid or Aldehyde and Acid vide p. 227 ^ , 1 yr , @— o Acetyl-aldehy^e + Acetic Acid :^ia^ -®— o Acetaldehyde. - Acetic Acid (hypoth.) Xetone-acida Acid and Acid vide p. 227 <®> i^ ■®— o Acetic Acid + Acetic Acid Aceto-acetio Acid Ketone- aldehydes Acid and Aldehyde vide p. 230 <£> ^i^ Acetic Acid + Acetic Aldehyde m Aceto-aoetic Aldehyde E B 4^ .f 1. Neutral Compound Ethers" Acid and Alcohol or Phenol and 2. Acid Compound Ethers Acid and Alcohol or Phenol vide p. 231 Acetic Acid + Methyl-alcohol Methyl-acetate 4~fi «'^''^' i^h ■ 4-f'^4-f° 6 ' & Ethyl-alcohol -I- Carbonic Acid -I- Ethyl-alcohol Ethyl-carbonate 4i Ethyl-alcohol -f Carbonic Acid Ethyl-carbonic Acid P P G G Ether-acids Hydroxy-add and Alcohol or Phenol vide p. 250 ,-4^ Methyl-alcohol + GlyooUic Acid 4. 4-i^ Methyl-glycoUic Acid Acid-anhydrides Acid and Acid vide p. 256 <^ ^,>^^ Acetic Acid -h Acetic Acid 1<^ <®>? . > I w : — g) . »^ ■ #— o Acetic Anhydride 208 OXYGEN-COMPOUNDS A. YOLO -ACIDS ITie first cyclo-hydrocarbon, it will be remembered, is trimethylene (fig. 112, p. 24), from which are formed 1. TrimetTiyleiie-carboxylic Acids We have already mentioned that itaconic acid (p. 196), in the opinion of some chemists, is a trimethylene-derivative ; that is, however, scarcely correct, because there is another legiti- mate possessor of that very structure, viz. trimethylene dicarboxylic acid, a compound quite distinct from itaconic acid (for illustration vide fig. 765, p. 196). Several other acids of the same structure but with more or less carboxyls belong to this class. 2. Tetramethylene-carboxylic Acids formed by joining one or more molecules of carbonic acid to tetramethylene or its derivatives. They would not haverequired more than a passing attention had it not been for one or two chemists having propounded the tetramethylene form for an acid derived from camphor by oxidation, camphoric acid, which has harassed many chemical brains as much as her mother, camphor itself (vide p. 143 &c.). As discussions are still going on, an account of the several interpretations of its strucbure may be acceptable to those who wish to understand what they are all about, although only tetramethylene-structures strictly have their right place here. For better com- parison I arrange those which have not hexagonal forms into that configuration also (compare diagonal-bond, p. 53), and place them in chronological order. Proposed structures of camphoric acid, G^^^fi^,'u^.^^. 180° (comp. also p. 144 &c.). 1873 i * Kekul6 {Ber. vi. p. 932) Fig. 800 Q -(©-^-O TETRA-MBTHYLENB CARBOXTLIO AOIDS 209 1873 Fig. 801 1877 FiQ. 802 Kachler {Ann. olsix. p. 192) Wreden (Ber. x. p. 714) 1870 to 1892 Fig. 804 O O & Victor Meyer (Ber. iii. p. 121) j Ball6 (Ber. xiv. p. 337) ; Koenigs and Eppens (Ber. xxy. p. 267) &o. 1892 Fig. 805 Fig. 806 Marsh (Proceed. Boyal S. xlvii. p. 6) Norman Collie (Ber. xxv. p. 1116) 210 OXYGEX-COMPOTJNDS In such an embarrassment of riches the difficulty of selection is increased when, on the one hand, authorities (Jour. pr. Ch. xlv. p. 475) tell us that the combustion-heat of camphoric acid agrees vrith its derivation from an aromatic chain, but not with any of the other structures ; and when, on the other hand, it is asserted, by equally high authority (BeUst, i. p. 631), that the possibility of any structure with an aromatic chain is excluded because aromatic amido-acids are coloured red by farfarol and amido-camphoric acid is not affected. Victor Meyer's &c. structure enjoys at present, I believe, most favour. After this little detour we can again go on with our cyclo-acids. 3. Pentametliylene-carboxylic acids formed from one or more molecules of carbonic acid joining the cyclo-hydrocarbon have also been prepared, but need no further mention. Amongst 4. Hexametliyleiie-carboxylic acids there is one, quinic acid, that needs illustration : it may be considered a derivative of a hydrated (vide p. 33) tetror-hydroxy-benzene, similar to the one given in fig. 425, p. 94, but with the hydroxyls close together (2:3:4:5), and carbonic acid ; or from a pentor-hydroxy-heasamethylene (fig. 426, p. 94) and forrmc acid, in both cases a molecule of water being separated as erplained by the formation of these acids in schedule p. 207. Pio. 807 Fig. 808 Fig. 809 or Tetra-hydroxy-liexametliyleno and carbonic acid Penta-hydioxy-liexamethylene and formic acid Quinic acid, hexahydro-tetra- hydroxy-benzoic acid, CiK^Jd^ ra.p. 161° In the opinion of other authorities quinic acid is derived from another tetra-hydroxy-hexa- methylene in which the two methylenes are in para-position, and not in ortho-position as in fig. 807, and carboxyl has replaced a hydrogen connected with one of the other carbon-atoms. It is found in quinine bark, bound to lime, and in coffee berries. AROMATIC ACIDS 211 5. Benzene-acids or Aromatic Acids A large series of benzene's and its derivatives' combinations with different acids exist, including many important compotinds. We can only study a few of the more interesting members, but sufficient to show the red tape running through them all. a. MOlSr-AOID PHENOLS' COMBINATIONS We commence, then, with fhenoVs (fig. 417, p. 92) combinations with the fundamental adds or benzene's combinations with hydroxy-acids (p. 178), which comes to the same thing when we remember that one molecule of water is separated in both instances, the hydroxyl being taken from that component which has it, and the hydrogen from the other, to form the requisite water. Theoretically both are equally correct, but practically benzenes (particularly those with side-chains) are employed when they are prepared at all .in this way. The first acid is formic acid or carbonic acid, the latter being considered in this instance hydroxy-formic acid (fig. 690, p. 179). The formation in both ways may be represented thus : Fig. 810 Fig. 811 Fig. 812 or G— ®— ■•O Carbonic acid and benzene Formic acid and phenol Benzoic acid, C^HaOa ; m.p. 121°-4 Benzoic acid occurs in gum benzoin, dragon's blood, Peru- and Tolu-balsam, castoreum, oranbeyries, &c. For medical use it should be prepared from benzoin by sublimation ; for other purposes it is generally prepared from toluene (fig. 232, p. 44) by oxidation or from the urine of horses and cows ; antiseptic. Its sodium salt is also employed. r 2 212 OXTGEN-OOMPOUNDS 'E'vom phenol and acetic acid or from benzene and glycollie acid (fig. 691, p. 179), we get phenyl- acetic acid. Fia. 813 Fhenyl-acetic acid, a-toluylic acid, CeHgOs ; m.p. 76°-5 ; used in phthisis and tjphna As the hydroxy-acid always corresponds to the fundamental acid it is unnecessary to specify more than one of them hereafter. Phenol's combination with propionic acid (fig. 669, p. 176) Hydrooinnamic acid, /3-phenyl-propionio acid, CaHmOa ; m.p. 48° ; used, like phenyl-acetio acid, in phthisis From phenol and isopropriomc acid (so called because the benzene-ring is joined to the inter- mediate carbon-link. Vide isopropyl, fig. 32, p. 11) : AEOMATIO AOIDS Fw. 815 O*^ 213 Hydratropio acid, a-phenyl-propionio acid, CgHxa02 ; b.p. 264"" Phenol and glycolUe acid (fig. 691, p. 179) Pia. 816 Mandelio acid, phenyl-glycolUo acid, CsHeOg ; m.p. 133° There are three optically difierent acids (see lactic acid, p. 179). For another combination of the two compounds see fig. 917, p. 251. When mandelic acid is cautionsly oxidised, the alcoholic carbon is either converted into carbonyl or another hydroxyl is added ; probably both forms exist, the former as crystals, the latter as an unstable fluid, which is easily converted into the former. Tio. 817 Benzoyl-formio acid, OaHaOa ; m.p. 65° Phenyl-glyoxylio acid, CaHaO^; oily liquid The latter when heated is converted into the solid acid, separating a molecule of water. Benzoyl-formic acid is strictly a ketone-acid (vide p. 227). 214 OXYGEN-COMPOUNDS "We have had analogous acids before, viz. elyoxalic acid, fig, 696, p. 180, mesoxalic acid, fig. 729, p. 187 &c. Phenol and hydraorylia a

iO Piperio acid, CiaHioO* ; m.p. 212° ; a decomposition product of pipeline (fig. 1431, p. 397) ; compare also safrol (fig. 504, p. 120), apiol (fig. 506, p. 121), and piperonal (fig. 564, p. 137) d. TBTRA-AOID PHENOLS' COMBINATIONS Tetra-acid phenol and forrrdc acid : There are three or four known out of a possible six acids ; as already explained, they may ■be considered as derivatives either of tetra-acid phenols and formio acid, or of t/ri-acid phenols and ca/rhonic add. From the latter point of view they have frequently derived their names ; thus the name of one of these acids is pyrogallol-carboxylic acid; another is termed phloroglucin- carboxylic acid; and a third, hydroxy-quinol-carboxylic acid, not yet isolated. The fourth and most important has no systematical name because it was known long before the law of the linking of atoms was thought of: it is gallic acid, 1:3:4:5 (carboxyl being=l). Fig. 834 1:3:4:5 Gallic acid, C,Ha05 ; decomposes on heating ; occurs in nutgalls, tea, claret, &<:. Pyrogallol-carboxylic acid has the structure (0OjH=l) 1:2:3:4, phloroglucin-carboxylio acid, 1:2:4:6. For hydroxy-quinol-carboxylic acid there are three structures to choose from ; which of them is the right one is not decided. 222 OXYGEN-OOMPOUNDS Basic bismuth gallate, containing 51-29-56-14 per cent, bismuth oxide (besides TSQ per cent, lead oxide, at least in one sample according to analysis, Ph. Ztg. 1892, p. 1) is, under the name of dermatol, recommended as a drying antiseptic, and has recently been used internally with advantage for diarrhoea in phthisis, typhus, malaria, and as a local anaesthetic {Int. hlin. Bundsch.). The formula 06H2(OH)3002Bi(OH)2 corresponds to 57-7 per cent. Bi^Oj (Bi=208). Tetra-acid jphenol and acrylic acid : An acid belonging to this series which has the name of ffisculetic acid, because its anhydride is named aesculetin, has not been prepared yet in isolated state, but some of its ethers have. One of its hydroxyls is in ortho-position to the carboxyl of acrylic acid, and it forms anhydride like so many of the acids just mentioned. The positions of the two other hydroxyls are 4 : 5. Fig. 835 Pig. 836 ^sculetic acid, CqEsOs Jiisculetm, CgHgOi ; m.p. above 270? ; exhibits in solution a powerful fluorescence ; occurs partly as sucli, partly as a glncoside, in the bark of .^sculus Mppocastanum When the two last-named hydroxyls are in positions 3 : 4, instead of 4 : 5, as in aBSCuletin, we have a similar anhydride called daphnetin, which occurs as a glncoside in the bark of Baphne aljaina. Tetra-acid phenol's four hydroxyls can each combine with formic acid, producing benzene- tetra-carboxylic acid. In the same manner jpenta- and hexa^-acid phenols form benzene- penta- and hexa-carboxylic acids. This last one is termed mellitic acid, Oi^HgOjj, occurring as aluminium-salt in honey-stone. e. MON-AOID TOLUENE PHENOLS' COMBINATIONS withfonmo add Three acids corresponding to the three cresols (figs. 428-430, p. 95) are known, tration of one of them will suffice : The illus- AROMATIC ACIDS Fig. 837 223 Ortho-toluio acid, CsHgO^ ; m.p. 102°-5 f. DI-AOID TOLUENE PHENOLS' COMBINATIONS with formic add, Prom the six possible di-acid toluene-2)henols (p. 96) ten different acids may be formed, and we know them all. They are distinguished by the common name cresotic acids, or systematically hydroxy-toluic acids ; singly they enjoy rather long names, which it would be purposeless to specify here. It may, however, be deemed interesting to see how so many different compounds can be arranged with the three groups, carboxyl, hydroxyl, and methyl ; therefore I give the figures represeiiting their respective places on the benzene-ring in the order just enumerated : 1:2:3 1:2:4 1:3:5 1:2:5 1:4:2 1:2:6 1:4:3 1:3:2 1:5:2 1:3:4 Here is an illustration of one of them : Fxa. 838 Para-homosalicylio acid, o-eresotic acid, or ortho-hydroxy-meta-toluio acid, OsHgOa ; m.p. 161° ; used in articular rheumatism, typhus, pneumxmia, &c., in children ; not poisonous Solutions of cresols in these acids or in their sodium-salt are known as lysol and solutol (vide P-96). It is not only the true phenols that form acids in this way ; any phenol-compounds which have 224 OXYGEN COMPOUNDS ahydroxyl free to join an acid can do so. Of such phenol-compounds we can mention phenol-alcohols (p. 106), and will give a few useful examples : g. PHENOL- ALCOHOLS' COMBINATIONS Tri-jahenol cwrKnol (fig. 466, p. 107) unites with forrmc acid, or phervyl-di-phenol-ca/rbinol (fig. 465, p. 107) with , ea/rbomic acid, forming an acid that has not yet been isolated, because the carboxyl goes from para- into ortho-position, and joins the alcoholic hydroxyl, separating a molecule of water and forming an anhydride (vide p. 108). Fio. 839 Fio. 840 Phenolphthalein, C20H14O4 ; m.p. 250° The smallest trace of an alkali colours its solution a magnificent pink, and acids, but not carbon di-oxide, destroy the colour. It is therefore one of the finest indicators of neutrality, especially for such acids as palmitic, stearic, oleic, &c. ; it cannot, however, be employed in the presence of ammo- nium-salts. Naphthalene-phenols similarly combine with acids. We are interested in only two of these com- pounds, santoninic acid and santonin. They have up to quite recently been regarded as hydrated (vide p. 33) oxy-di-methyl-naphthol's (vide fig. 453, p. 103) combination with hydracrylic acid (vide fig. 693, p. 179), Pig. 841 Santoninic acid, OisHjoOj ; sodium santonate is a vermifuge PHENOL-ALOOHOLS' COMBINATIONS 225 On heating it forms a lactone (p. 182), the carboxylic and alcoholic hydroxyls in the side-chain uniting by the separation of a molecule of water and forming (Ber. xviii. p. 2748) Fib. 842 Santonin, C15H15O3 ; m.p. 170° ; anthelmintio But, according to later researches (Ber. xxv. p. 3318 and xxvi. pp. 411, 786, April 1893), this structure is incorrect. In the opinion of one authority these compounds are to be looked upon as a combination of a hydrated j8 : ^-di-hyd/romj-nofphtJialene with 'pyroracemio acid (fig. 851, p. 2^7). The consequence as regards the structure is that the hydroxyl of the side-chain takes the place of carbonyl (the ketone index) in the naphthalene-ring, while the latter goes into the side-chain. A further consequence is that the formation of santonin is not a performance exclusively in the side- chain, as represented above, but an operation in which the naphthalene-ring takes a part through its hydroxyl by the formation of three interlocked benzene-rings. The two compounds interpreted in this way would, therefore, have such structures : Fio. 843 Fia. 844 O 4 "O Santoninic acid In the opinion of the other authority the two compounds are somewhat related to terpenes, or, better still, a combination of na^MJialene-iormed. terjpene with iso-^ojpionic acid : Q 226 OXYGEN-COMPOUNDS Fig. 845 Fig. 846 Santoniuic acid Santonin h. DI-HYDROXY-NAPHTHALENES' (/3-lTaplitliol-quinol, fig. 455, p. 104) COMBINATIONS ivith formic acid Out of fourteen possible isomers eight have been prepared, one of which is Fig. 847 a- Hydroxy-naphthoic acid, a-naphthol-carboxylic acid, o-oxy-naphthoio acid, CnHsOg ; m.p. 185° ; more powerful antiseptic than salicylic acid, and a very effective antizymotic and antipyretic (in fever internally, but with caution, as it is poisonous ; in diseases of the skin — scabies, prurigo — externally) ; used, under the name of sternutament, as snuff for nasal catarrh ALDEHYDE- AND KETONE-AOIDS 227 B and 0. ALDEHYDE- AND KETONE-AOIDS When formic acid through its carboxyl (or an aldehyde through its alkyl) joins the alkyl-part of another acid, aldehyde acids are formed ; any other than formic acid produces ketone acids. Excepting formic acid itself, which may be looked upon as the first member of this class, the first of the aldehyde-acids is formed from two molecules of formic acid, viz. glyoxalic acid, which has already been mentioned under di-hydroxy-acids of the fundamental series (fig. 697, p. 181), and we will therefore commence by joining formic and acetic acids in the way mentioned, producing the next aldehyde-acid, i.e. a compound which is acid at one end and aldehyde at the other. G- Fio. 848 Fig. 849 Formic acid acetic acid Formyl- acetic acid, C3H4O3 ; easily oxidised to malonic acid (fig. 713, p. 184) Owing to the peculiar structure of formic acid in having no alkyl-body, but being itself aldehyde at one end and acid at the other, it would naturally form aldehyde-acid in the same way from all other acids if capable of existence; they are, anyhow, not known; but not so when formic acid is converted into a higher homologue with alkyl-body by substituting a hydrocarbon - radical for its hydrogen — methyl, for instance, converting formic acid into acetic acid (vide p. 175). Therefore if we join acetic instead of formic acid to another acid we obtain a compound which has not an aldehyde in its body, but a ketone (p. 138) ; for instance : Fig. 850 Fig. 851 ^ ^ -O Acetic acid + formic acid Fig. 852 Pyro-racemio acid, C3H1O3 ; b.p. 165" Fig. 853 -(i— O Acetic acid acetic acid Aceto-aoetic acid, C^HeOa ; decomposes belov7 100' is found in urine in diabetes mellitus q2 228 OXYGEN-COMPOUNDS Fia. 854 FiQ. 855 o»- ;; I <^ -#— © o <2> I 1 6 6 -#— © Acetic acid 4- propionio acid Levulinic acid, /3-acetyl-propionic acid, CsHsOa ; m.p. 33°-5 There are many more of this series, but the three above are some of the. better known compounds. The structure of aceto-acetic acid, which differs in some respects from the rest, has been very- much discussed. It seems as if the structure were labile, i.e. that it assumes different forms according to circumstances : we have seen instances of this before (glyoxalic acid, fig. 696, p. 180, and mesoxalic acid, fig. 729, p. 187 ; compare also what is said about the double bond in benzene, p. 54). Through being enclosed between two carbonyls (ketone-index), methylene is equally at- tracted to both, swinging to and fro like a pendulum. If, now, anything happens to lessen the attention which one of the carbonyls is paying to the hydrogen in the methylene-group (and this will occur from the attachment of something very attractive to the carboxyl-group), then the other carbonyl gets the advantage of the hydrogen which jumps over to the oxygen, whereby two valencies are released, and join each other forming a double-bond. Fig. 856 Fia. 857 4*t This is termed the alcoholic form of aceto-acetic acid, whereas the former is the ketonic form. Some chemists frill, of course, not admit this duplicity of the hydrogen, and stick to the ketonic form through thick and thin. The two other ketonic acids with no such vacillating hydrogen, having either two hydrogens or none at all between the two carbonyls, are beyond suspicion and doubt. Another remarkable property of aceto-acetic acid, or practically its ethers (vide p. 232), is that the hydrogens of methylene can be replaced by alkali-metals (but only one at a time), alcohol- radicals, acid-radicals, and elements and groups, some of which will be subsequently mentioned, e.g. iso-nitroso-group, imido-group, chlorine, &c. That makes the acid one of the most useful compounds in chemical synthesis. There is still a group of ketone acids which should not escape our attention, the tannic acids, prepared from the various barks. Some of the tannic acids appear to be glucosides (gummides, dextrides), but the oak-tannic acids are, according to the latest researches {Monatsh. x. p. 647), ketone acids, formed from the cwriovyyl of one molecule of gallic acid (fig. 834, p. 221) joining a ienzene-hydrogen of another molecule of the same acid, separating, of course, a molecule of water. KETONE-AOIDS 229 FiQ. 858 Fia. 859 Two molecules of gallio acid Oak-tannio (querci-tannio) acid, Cj^HioO, There are several hofaologues of tlie acid according to the different varieties of oak from which they are prepared. Their differences consist in the etherification of the acids by the joining of methyl to the phenol-hydroxyls : Fig. 860 Oak-tannio acid, CigHi^Og ; with two methoxyls There are acids with four methoxyls, OigH,gOg, and with six methoxyls, OjoHjjO, 230 OXYGBN-OOMPOUNDS The tannic acids are, of course, used for tanning, and in this respect, as also in structure, are distinguished from tannin, which is a compound-ether-aoid (fig. 926, p. 255). D. KETONE-ALDBHYDES being, at present, of little interest from a therapeutical point of view, the description of their forma- tion given on p. 207 will suffice, and we can pass on to consider the combinations of acids and alcohols, or phenols — the compound ethers. COMPOUND ETHERS 281 E. COMPOUND ETHEES, NEUTRAL AND AOID (ESTEKS AND ESTEE-ACIDS) When acids combine with alcohols or phenols through their carboxyl- and hydroxyl-parts they are termed ethers on account of their analogy to the true ethers (p. 113), both in their formation and in many physical properties. The ethers were formed from two alcohols (or phenols), joining under separation of a molecule of water; the compound ethers are formed from an alcohol (phenol) joining an acid under the same condition. In the case of polybasic acids as many mole- cules of (the same or different) alcohols may join as there are carboxyls with which to effect a union. When all carboxyls are thus engaged neutral compound ethers are formed : if not, they are acid compound ethers. Compound ethers are by German chemists distinguished as ' esters.' There are a great many compound ethers ; we can only reproduce a few of them, limiting ourselves to those that are typical or possess some interest to the reader. We may classify them into combinations of Aliphatic Acids with Alcohols Phenols Cyclo-acids „ Alcohols Phenols !) !) I. AliptLatic Acids and. Alcohols a. MONOBASIC ACIDS AND MONAOID ALCOHOLS These ethers possess for the most part a pleasant fruity smell. Fig. 861 Fio. 862 O - w^ » ® — ' m O Methyl-formate, C2H4O2 ; b.p. 32°-3 ; occurs in crude wood-spirit Ethyl-formate, CsHaOa ; b.p. 54°-4 ; used in the artificial preparation of rum and arrack Fig. 863 Methyl-acetate, CaHeOa ; b.p. 57°-5 ; occurs in crude wood-spirit Fig. 864 -^ Ethyl-acetate, acetic ether, C^HgOs ; b.p. 77° 232 OXYGEN-COMPOUNDS Pia. 865 a Q a Fig. 866 6 d 6 6 CD Amyl-acetate, CHi^O^ ; b.p. 148° ; BmeU of jargonelle pears ->0 Ethyl-butyrate, CsHisOa ; b.p. 121° ; smell of pineapples Fio. 867 Iso-amyl-iso-valerate ; b.p. 196° ; smell of apples What is called ' bouquet ' in wine, or oenantheiher, is a mixture of ethyl-, oenanthyl-, caprylyl-, pelargonyl-, and capryl-ethers at the ratio of 1 to 40,000 parts of wine. The fruit essences are artificial mixtures of these ethers ; perhaps the composition of some of them may interest. Apple Essence : iso-amyl-iso-valerate Apricot „ amyl-butyrate Cherry „ ethyl-acetate and benzoate Cognac ,, ethyl-acetate and nitrite Melon „ ethyl -sebacate Mulberry „ ethyl-suberate Pear „ iso-amyl-acetate and ethyl-acetate (10 : 1) Pineapple „ ethyl-butyrate Quince „ ethyl-pelargonate Rum ,, 'ethyl-formate mixed with some other ethers Strawberry,, ethyl-acetate and butyrate, and iso-amyl-acetate (Beilst, i. p. 426.) Amongst the compound ethers of the higher alcohols and fatty acids may be mentioned : Cetyl-palmitate, ^ib^n C/O-O-OigHgj, the chief constituent of spermaceti Melissyl- (myiicyl-) palmitate, O15H3, OO-O-CgjHgj, in bees-wax, Ceylon and Camauba wax Ceryl-cerotate, C'as-'^sa OO-O-Cj^Hjj, occurs in Chinese wax The structures of compound ethers formed from other than fundamental acids are in every way analogous to the above. One of them is worth mentioning because of its ability to unite with other compounds, and- afterwards to split up in different ways, wherefore it is being largely used in modem synthetical processes. It is the combinations in ether-fashion of aceto-acetic acid (fig. 853, p. 227) and alcohols, the aceto-acetic ethers : Fig. 868 6 (H Aceto-aeetio ethyl-ether, CeHjoOs ; b.p. 181° COMPOUND ETHEES 233 The two methylene-hydrogens between the carbonyls may be replaced by various substitutes mentioned under aceto-acetic acid, p. 228. It is split up in two ways, according to the reagents employed : one is termed ketonic decomposition: Fio. 869 •e -1- + G- Aceton (oomp. fig. 566, Carbon dioxide p. 138) (fig. 711, p. 184) Ethyl alcohol (fig. 337, p. 70) The other is termed acid decomposition: Two molecules of acetic acid (fig. 667, p. 175) Ethyl alcohol For its behaviour in other respects compare what is said about aceto-acetic acid, p. 228. b. MONOBASIC ACIDS AND POLYAOID ALCOHOLS The polyacid alcohols can join an acid to every one of their alcoholic hydroxyls ; e.g. glycol (fig. 364, p. 76) has two hydroxyls of which one or both may be joined to acetic acid Pig. 871 Ethylene-monacetate or ethylene monacetin, CiHgOa ; b.p. 182!> Ethylene-diaoetate or ethylene diaoetin, CeHioO^ ; b.p. 186° but they are not of much consequence until we come to glycerin (fig. 375, p. 78), which forms with the higher homologues of the aliphatic acids some of the most widely spread compounds in nature, the fats. Glycerin combines with the higher homologues of the aliphatic acids exactly in the same way as with the lower homologues ; therefore a few examples of the last will serve as an introduction- to the more important compounds. On account of their many analogies and their great importance as a class, their names have been fashioned in one mould, the sujQax '-ate ' of the acid being changed to '-in,' and mono-, di-, or tri- plrefixed to indicate how many molecules of acid have entered into the compound; e.g. mon-acetin, di-acetin, and tri-acetin, &c. As a class they are all termed glycerides, distinguished as mono-, di-, or tri-glycerides. 234 OXYGEN-COMPOUNDS Glycerin's combinations with acetio acid are Pia. 875 Fig. 873 Pig. 874 Monaoetin, CsHmOi ; b.p. not stated; mono-glyceride Diaoetin, CYH12O5 ; b.p. 280° ; an isomer with acetyl in j8-position has b.p. 250° ; di-glyoeride Triaoetin, CaHitOj ; b.p. 268° tri-glyoeride The latter occurs in small quantities in oil from the seeds of Hvanymus eurojpoeus, is said to have been found in cod-liver oil, but probably only as a product of decomposition. In the same way glycerin combines with buiyric-, valeric-, caprma-, ca/prylicr-, ca/pric-, lauric-, myristic-, palmitic-, stearic-, arachidAo-, and oleic-acids, all of which in the form of tri-glycerides have been found in pure butter ; further, with hehenic-, lignoceric-, emcic-, theoiromio-, hypogceio-, physetoleic-acids found in other fats ; and linolic-, linolenic-, and iso-Unolerde acids in linseed oU ; with ricinoleic acid in castor oil, and with jecoleic and therapic acids in cod-liver oil, always as tri- glycerides. Only tri-glycerides are found in nature, except in some more complex compounds where one of the hydroxyls in glycerin is used to connect the glycerides with some other compound (vide lecithin, fig. 1536, p. 435). The acids united to one molecule of glycerin in form of compound ethers are usually of the same sort, though not necessarily so ; for instance, a tri-glyceride found in butler is an oleo-palmito-butyrin (Ch. Ztg. 1889, xiii. p. 128 ; Benedikt Fette, p. 391). Fig. 876 13 L14^ Oleo-palmito-butyrin, CtiH^eOe ; crystals COMPOUND ETHERS The most important of these tri-glycerides are 235 Palmitin (tri-palmitin) Fio. 877 Palmitin, CsiHggOj Palmitin melts first at 50°-5 ; on further heating it solidifies and melts again at 66°-5, a rather uncommon and remarkable behaviour. (BenediM Fette, p. 36 ; Schaedler Technol. i. p. 164, gives even three different m.p.) It occurs in nearly all fats, but is particularly abundant in palm oil. It is also found in cod-liver oil to the extent of probably less than 5 per cent., retained in solution in the fluid part of oil, even if it has been kept for several days at a temperature of — 7° of cold, although palmitin by itself solidifies, as already stated, at a temperature between 50° and 60° Stearin (tri-stearin) Fig. 878 Stearin, CajHuoOa Stearin, like palmitin, melts twice on heating, first at 55°, solidifying on further heating and melting again when the temperature has reached 71°'5. It occurs in nature nearly always in company with palmitin. Ood-liver oil on cooling towards the freezing-point throws down a crystalline mass which has hitherto been mistaken for stearin. The greater part of it consists of glycerides of unsaturated acids. 236 OXYGBN-OOMPOUNDS Olein {tri-olein) Fia. 879 ) \ (!> / 6 6 ° '13 13 ^m- Olein, Cs^HioiOe Olein is liquid and solidifies at —6°. It is converted by nitrous acid into elai'din, a solid compound wHcli melts at 44° and possesses the same geometrical structure as olein. The difference between them is of a stereometrical nature and fully analogous to that of oleic- and elaidic-acid or erucic- and brassidic-acid (vide pp. 190, 191). Oleiin is widely distributed in nature. There are very few fats which do not count it amongst their constituents. Jecolein (tri-jecolem') Fig. 880 X y Jeooleiu, CgoHuoOe i a: + y = 15 ; j/ is probably a considerably higher figure than a; Jecolein, recently found by Heyerdahl in cod-liver oil, is one of the constituents of that part of the oil which has hitherto been ta;ken to be exclusively olein. It is present in the oil to the extent of about 20 per cent. Ricinolein (pri-^icinolein) Fig. 881 (})f^ TTtw 0/6 4 i>\ili 5 9 Bicinolein, Cs^E^g^Og COMPOUND ETHERS 237 It appears that castor oil contains two isomeric ricinoleins, one fluid, the other solid. Neither of them has been isolated free from impurities. Linolin Pia. 882 ^4W^ ■®— (h-o rilDn-dW^ ■^(-1 ) ^^ ( I)^ ' HI)I Linolin OsTHgsOa Linolenin Fia. 883 H " l'n " 'i M ^i ) "(ti"(i) " ii) Linolenin, C57H920a were until recently considered one compound, Unolein. They occur in linseed oil. Therapin FiQ. 884 ([j)lJ(j)LJ ( I)LJ ( i) II ([)^ (l)ri( l )< rratnttrrmfrnt^ mwHiMi Therapin, CsiHgoOe Therapin has been found in cod-liver oil only, and is without doubt one of the active principles of that valuable remedy. It is present to the extent of 20 per cent, in cod-liver oil, but has not been isolated in a pure state, as it decomposes with such extreme ease. Together with jecolein and some other not yet known glycerides, it has, until now, been mistaken for olein. FATS The natural fats consist almost exclusively of the tri-glycerides which we have just been discussing. Most of them contain palmitin, stearin, and olein in varying proportions. Some are solid because their chief constituents are palmitin and stearin; others are fluid when olein is predominant. Some originate in the vegetable world, others are animal fats. 238 OXYGEN- COMPOUNDS All vegetable fats seem to contain some linolin, of which animal fats are entirely free (Monatsh. X. p. 190 &c.). Palm oil and cacao-butter are solid vegetable fats, the former containing free palmitic acid besides the glycerides. The fluid vegetable fats are oils of which some, by the action of air, are transformed into a solid substance, and others are not. The former are termed ' drying oils,' and owe their property to a preponderance of linolin and linolenin in their constitution. The principal drying oil is Unseed oil ; others are poppy, hemp, and walnut oils. Of the non-drying oils there are cotton oil, almond oil (which contains exclusively olein and a little linolin, but no saturated acids), oUve oil, rwpe oil, sesam oil, and castor oil. Solid animal fats are numerous, as everyone knows. We have already been informed, p. 234, of the complex constitution of butter ; goose-fat is palmitin, stearin, and olein with glycerides of the same volatile acids as in butter, for which it therefore sometimes serves as a substitute on bread. Mutton-suet is essentially stearin with a small percentage of palmitin and 25 per cent, of olein ; heef- suet has the same amount of olein as mutton-suet, but more palmitin. Lwrd has 60 per cent, of olein, and the rest is palmitin and stearin. Humam fat in infants has three times as much palmitin and stearin as the fat of grown-up people, and one-third less olein : that accounts for our own flabbiness, whilst our babies are plump bonny little beauties. Oho-mm-gwrin or artificial butter is prepared from various sorts of tallow carefully melted with water and potash ; and after being cooled, subjected to hydraulic pressure at a temperature of 20-22°. That portion which goes through the press at this temperature is oleo-margarine, which is then heated with milk and agitated or churned just like ordinary butter. Some butter-colour and perfume (butyric ether and coumarin) put on the finishing touch. What remains in the press is stearin, used for candle-making. There are two kinds of animal oils : hluiher-oils and liver-oils. Some of the former are seal-oil from difierent species o{ Fhoca, whale-oil from whales, bottlenose-oil from Belphinus globiceps, porpoise- oil from Belphinus phoccena (contains 10 per cent, or more of valeric acid), menhaden oil from Alosa menhaden, sa/rdine- and herring-oil from Glupea sa/rdinus, ha/rengus ; dugong-oil from the blubber of a large fish (strictly a mammal, Heliocre dugong, in Australian and East Indian waters), &c. These are aU used for technical purposes only, particularly in the tanning process (except when there is a scarcity of cod-liver oil). Dugong oil has been used as a substitute for cod-liver oil, but in a legitimate way. The only liver oil in medical use is codAiver oil from Oadus morrhua. Up to now it has been supposed to consist, like other fats, chiefly of palmitin, stearin, and olein (95 per cent.). Heyerdahl in his researches has proved the fallacy of these suppositions : there is but a small percentage of these acids in the oil, whilst, on the other hand, he has found and determined two hitherto unknown acids, mentioned before — the jecoleic acid and the remarkable therapic acid. When, through any operation, the alcohol and the acids in the compound ethers are separated the process is called saponification. This may be done by heating the ether with dilute sulphuric acid at a temperature of 110-115°, or with milk of lime at 170° under pressure; or it may be boiled with caustic soda or potash, when sodium or potassium will replace the alcohol, and in the case of glycerides form soaps ; those with sodium form hard (toilet) soaps, those with potassium soft soaps. When solutions of soap are treated with sulphuric acid or any other strong acid the alkali is seized by it, forming salts, sulphates, &c., and the fatty acids are set free. Pats exposed to the influence of air become rancid ; a fact only too well known. The chemical nature of this process in all its details are, however, difficult to get at on account of the complex nature of the fats and the great difficulties in recognising and separating compounds so closely allied, both physically and chemically, as the higher homologues of the fatty acids. It is generally represented as a splitting up of the glyceride-molecule through the action of the oxygen of the air, setting glycerin and acids free, afterwards converting the free acids into hydroxy-acids, and by prolonged action splitting both them and the glycerin up, the ultimate products being, as always, carbonic acid and water. Heyerdahl's researches seem, however, to prove that rancidity — in cod- COMPOUND ETHERS 239 liver oil at any rate — is solely due to introduction of hydroxyls into the glycerides, and not to formation of free acids by splitting up the glyceride-molecule, because he found that by keeping the oil heatedfor hours at high temperatures (200-300°), while conducting a current of air through it, the rancidity of the oil increased enormously, the acid value at the same time increasing but little (from 0-72-0-77). As it may often be of. importance to ascertain with exactitude how rancid a fat is, or, in other words, how many molecules in a fat have added hydroxyls to themselves (i.e. the proportion of hydroxy-acids in a fat), a process has of late years been devised for this purpose : it is based upon the behaviour of acetic acid towards hydroxy-acids in driving the hydroxyls out and taking their place in the compound as acetyls. Suppose we have two molecules, one of butyric acid and the other of hydroxy-butyric acid. Fia. 885 Fig. Butyric acid, O^HaOa r Hydroxy-butyric acid, C^HaOj If one hydrogen-atom weighs 1, an atom of carbon weighs 12, and an atom of oxygen 16 (vide 3) as a consequence : One molecule of butyric acid weighs : 0, = 4 X 12 = 48 Hg = 8 X 1 = 8 Ojj = 2 X 16 = 82 One molecule of hydroxy-butyric acid weighs C^ = 4x12 = 48 H„ = 8 X 1 = 8 O3 = 3 X 16 = 48 104 The two molecules together weigh 192. Now if we let acetic acid act upon the two molecules it will not affect the butyric acid, but will join the other on account of its alcoholic hydroxyl, forming a compound ether-acid on separating a molecule of water. Fig. 887 Fia. 888 ©•— @— €> Acetic acid + hydroxy-butyric acid ■©— »o Aoetyl-hydroxy-butyric acid, C^B.^oO^, 240 OXYGEN-COMPOUNDS The weight of the two molecules after acetylisation is therefore : One molecule of acetyl-hydroxy-butyric acid— One molecule of butyric acid — 0, = 4x 12=48 Hg=8x 1= 8 02=2x16 = 32 and their aggregate weight (88 + 146) = 234. 06= 6x12 = 72 H,o=10x 1 = 10 0^= 4x16 = 64 146 When we add, without application of heat, potassium-hydrate (KOH) to these acids, potassium will replace hydrogen in each carhoxyl. Fig. 889 - ■ if i.— (g)— Fia. 890 M Carboxyl and potassium hydrate o«— ®— O Potassium salt and water and as there are two carboxyls in the original two molecules as well as in the acetylated molecules, two molecules of KOH are in both cases required to neutralise the acids. One atom of potassium weighs 39" 1 ; consequently a molecule of potassium-hydrate (KOH) weighs (39-1 + 16 + 1)= 56-1, two molecules 112-2, and three molecules 168'8. If we boil the acids with more KOH, the original acid will remain unaltered, but in the acetylated acid a third potassium-atom will split off the acetyl, forming potassium-acetate, and the original hydroxyl will be restored to the acid : Fig. 891 Pia. 892 Potassium-acetyl-hydroxy-butyrate + potassium hydrate Potassium-acetate and potassium-bydroxy-butyrate COMPOUND ETHERS 241 _ We are now able to explain how these processes are utilised in the examination of oils or fatty acids. We have seen that by the action of cold KOH two atoms of potassium will neutralise the two molecules of the original acids, and that the two molecules of aoetylated acids will require the same quantity. Suppose, therefore, we had 192 milligrammes of the original acids, we should find 112-2 milli- grammes of KOH were required to accurately neutralise them. This quantity reduced to 1,000 milligrammes = 1 gramme of the original acids (J-J ^'^^^^^) would make 584'4, which figure is termed acid-value. We saw that 192 milligrammes of the original acids when acetylated would weigh 234 milli- grammes. When treated with cold KOH these acetylated acids would require the same quantity (112-2 milligrammes) of KOH as the original acids for neutralisation, which, if reduced to 1,000 milligrammes of the acetylated acids (^^- 'IH"^ ' ^ ) would make 479-5 milligrammes, which figure is termed acetyl-acid-value. If we now boil these neutralised acids with more KOH, the original acids will not be acted upon, as already mentioned, but in the acetylated acids further 56-1 milligrammes of KOH will be used in splitting off the acetyl. This quantity reduced to 1,000 milligrammes of the acetylated acids ( ^^ ' Vs'4'^ ^^) inakes 239-7 milligrammes, which figure is called acetyl-value. If we do not first neutralise the acids, but at once boil them with KOH, we shall of course find that the original acids require, as before, 112-2 milligrammes (two molecules) for saturation, which, reduced to 1,000 milligrammes of the original acids (^-^-'y^^^^^}, makes 584-4, and is termed saponification-value, which in this case is identical to acid-value. But if we boil the acetylated acids, before neutralisation in the cold, with KOH, we find that I68-3 milligrammes are required (three molecules, two for neutralisation and one for splitting off the acetyl); reduced to 1,000 milligrammes of the acetylated acids (i^^|^|i^^= 719-2), the figure 719-2 is termed acetyl-saponification-value. It will thus be seen that acetyl-value is the difference between acetyl-acid- and acetyl-saponification- values, and the latter is the sum of acetyl-acid- and acetyl-values ; therefore, when acetyl-acid- and acetyl-saponification-values agree, and acetyl-value is consequently = 0, no hydroxy-acids can have been present in the compound examined. By simple calculation we find that if a cod-liver oil has acetyl-value 2, then it contains about 0-15 per cent, of hydroxylated acids, provided the glycerides have about the same molecular weight as therapin or jecolein. Hydroxy-acids not unfrequently show a too low acetyl-value, when they have a hydroxyl in 7-position, because in that case some of them will form lactones (vide p. 182), upon which acetic acid has no effect. For quantitatively determining the free fatty acids in a fat or oil no method has been devised except when the sort of acids present and their relative proportions are known. It is, however, sometimes useful, for the sake of comparison, to know how much potassium-hydrate is required for neutralising such free acids, but it gives no clue to what sort of acid has been neutralised. If, for instance, we say that a certain specimen of cod-liver oil has an acid value of 7-38, and another of 0-34, that does not convey the slightest idea as to the sort of free acids. In such cases it is generally referred to as oleic acid, although there may not be any free oleic acid at all present in the fat or oil. The acid- value is therefore only useful for comparing the same sort of fats, in which we may presume there would be present the same acids in the same proportions. Finally, a method for determining if any unsaturated acids are present in a fat may be mentioned 'here, although we shall be obliged to treat by anticipation of an element which will have to be subsequently mentioned in its proper place, viz. iodine.. It will be remembered that unsaturated acids — those with double bonds— can add two hydrogens to each double bond, converting them thereby into saturated acids with single bonds (vide p. 23). But hydrogens are not the only additions that can be made to the double bonds. The elements of water may be added, as we have seen, one of the valencies taking up the hydroxyl R 242 OXTGEN-OOMPO UNDS and the other the hydrogen, or two hydroxyls may be added to each double bond. The elements '^^|°^i'ie> bromine, and iodine are also among the additions a double bond will accept. Thus, if we add iodine in excess to an unsaturated acid a certain quantity will be absorbed by the acid and the rest will remain free and unaltered. The quantity of this rest can be determined by analysis, and we then know how much has beeii absorbed. This absorbed quantity reduced to per cent, of the acid or fat (iodine being absorbed by glycerides as well as by free acids) is termed iodine- absorption. Taking, for instance, the molecular weight, 282 (grammes, decigrammes, or any other unit of weight), of oleic acid, and adding 632-5 (i.e. 6 x 126-5, the atomic weight) of iodine, we can illus- trate that as one molecule of oleic acid and five atoms of iodine ; iodine we propose to represent by this symbol, -*^ Fig. 893 1 Jt u'U Fig. 894 One molecule of oleic acid + five atoms of iodine Di-iodo-oleic acid + three atoms of iodine We then learn that out of the 632-5 iodine only 379-5 are to be found as free iodine in the resulting products ; consequently 253-0 have disappeared, i.e. have been absorbed by the oleic acid. These 253-0 calculated as per cent, on the quantity of oleic acid make (- ^^|ga^^ ) = 89-7. Such a figure is termed the iodine absorption of oleic acid. This method appears to give good results for oleic acid, and perhaps for some more of the acids with one double bond ; but for oils containing several double bonds, the absorption is so much dependent on the time of action, on the concentration and relative proportions of the solutions employed, on the temperature, and on the solutions being freshly prepared or not, that it is only of value as a comparative agent to be employed under exactly the same circumstances in all cases. Uut employed with these precautions as a comparative method, it is sometimes possible to draw valuable conclusions as to the constitution of various fats if utilised, as it was by Heyerdahl in his researches on cod-liver oil. c. POLYBASIO AOIDS AND ALCOHOLS Neutral and acid compounds are formed according as all, or only some, of the acid's carboxyls are joined by alcohols. Malonic acid (fig. 713, p. 184), for instance, forms two ethers, one in which both carboxyls are united to an alcohol, the neutral compound, and another in which only one of the carboxyls is so engaged, the acid compound : Fig. 895 G— @- ^X^ -O i) do Ethyl-malonio acid, C5H8O4; m.p. lll°-5 ; acid compound ether Fig. 896 < > c t < :>i tc ^ ,] ) < » < 1 c r ' @) — "- 1 < 1 C ) ( » Malonic ether, ethyl-malonate, C^HiaOt ; b.p. 198° neutral compound ether COMPOUND ETHERS 243 A dibasic acid, also called ethyl-malonic acid, exists, in which ethyl forms a side-chain in malonic acid — consequently not a compound ether, but an isomer to pyrotartaric acid (figs. 719 and 720, p. 185). Malonic ether has a striking resemblance to aceto-acetic ether (fig. 868, p. 232). They both have a methylene between two carbonyls, and they have therefore the same chemical properties, as explained on p. 228. II. Aliphatic Acids and Phenols Examples of this class are Fib. 897 Phenyl-aoetate, CgHaOs ; b.p. 193° From a phenol-ether, guaiacol (fig. 499, p. 118), and a dibasic acid, caroonia acid, a neutral compound ether is formed : PiQ. 898 Guaiaool-oarbonate, C15H14O5 ; m.p. 85° ; antiseptic and antipyretic ; used for tuberculosis, especially for phtliisis, as a substitute for cieasote and for the pure guaiacol, it not aflecting the stomach R 2 244 OXYGEN-COMl^OUNDS Also the acid compound is known : Fig. 899 Guaiaool-oarbonio acid, OaHsO^ ; m.p. 150° ; antiseptic and antipyretic Creosotalis a new remedy prepared from 'sodium-creosote and chloro-carbonic acid' (carbonic acid in which one of the two hydroxyls (p. 273) has been displaced by chlorine). In the case of creasote from wood-tar being employed creosotal will be identical with guaiacol-carbonic acid ; creasote from coal-tar would form phenol-carbonic acid of analogous structure {vide creasote, p. 119). It is not stated which creasote is to be employed, but probably that from wood-tar is meant. Similar combinations of guaiacol and creosol (from wood-tar creasote), or phenol and cresol (from coal-tar creasote) with oleic acid, have been prepared, and are known by the names of oleo-guaiacol and oleo-creasote : substitutes for salol (comp. p. 248). III. Oyclo-acids and Alcohols When methyl-alcohol is joined to the carboxyl of salicylic acid (fig. 823, p. 215) a compound ether is formed : Fia. 900 Methyl-salioylate, CsHeOg ; b.p. 224° ; chief constituent of winter-green- •{gaulteria-) oil (90 per cent.) used for articular rheumatism COMPOUND ETHERS J{ methyl-alcohol joins the phenol-hyd/rossyl an ether acid (vide p. 250) is formed: 245 Fig. 901 Methyl-salioylio acid, CoHgOa ; m.p. 98°-5 • and if methyl-alcohol joina both the ea/rboxyl- and the phenol-hy(hoi^l we have again a compound ether : Pio. 902 Di-methyl-Balioylate, OgHioOa ; b.p. 228° IV. Oyclp-acids and Plieiiols From salicyUc add and phenol : Fio. 903 Salol, phenyl-salicylate, CisH^gOs ; m.p. 42° ; used for acute rheumatism, and externally as an antiseptic and deodorant like iodoform. It has its name, not from salicyl and phenol, which seems a natural conclusion, but from a Dr. Sahli, who was the first to recommend and report upon it {Heger. neue Arzneim) 246 OXYGEN-COMPOUNDS WieD its sodium salt is heated to 300° the phenyl jumps over to the phenol-hydroxyl (intra- molecular change, vide p. 40) and forms an ether-acid (vide p. 250). Fio. 904 Phenyl-salicylio acid, CjaHioOa {Ber. xxi. p. 501) Salacetol, m.p. 71°, is a compound in which acetone, instead of phenyl, is joined to salicylic acid in salol : recommended as an improvement upon salol. From joa/ra-cresotic acid (fig. 838, p. 223) and johenol we obtain Fia. 905 Methyl-salol, phenyl-para-eresotate, C14H12O3 ; m.p. 92° ; antirheumatic, analogous to salol From saUcyKo acid and paranyresol (fig. 430, p. 95) : Fia. 906 Cresalol, para-oresol-salicylate, C14H12O3 ; m.p. 39° ; used as substitute for salol COMPOUND ETHERS Fi'om anisic acid (an ether-acid, fig. 918, p. 251) and phenol: 247 Fig. 907 Phenyl-anisate, Ci^HiaOa ; m.p. (?) ; antirheumatic, analogous to salol From benzoic acid and guaiacol : FiQ. 908 Benzosol, guaiaool-benzoate, benzoyl-gualaool, CjiHijOa ; m.p. 50° ; used in phthisis From salicylic acid and guaiacol : Fig. 909 Giiaiaool-salioylate, O14H12O4 ; analogous to the other guaiacol-compounds '248 OXYGEN-COMPOUNDS From cinnamic acid (fig. 821, p. 214) and guaiacol: Fig. 910 Styraool, oinnamyl-gaaiacol, OigHiiOa ; m.p. 130° ; is recommended as a powerful antiseptic, internally for phthisis, bleunorrhcea, and gonorrhoea, and as an intestinal antiseptic ; externally it acts like iodoform. The object of all these synthetical compounds of guaiacol is to avoid the injurious effects of the pure drug upon the mucous membrane of the stomach. They all pass unaltered, or almost so, through the stomach, because of the' acidity of its contents; but when they reach the small intestines and are mixed with the alkaline pancreatic juice, they break up into their components (saponification). Besides, the pure guaiacol has a loathsome taste, which is entirely disguised in these compounds. We know also compound ethers formed from naphthol. Thus from ^^naphthol and salicylic acid (fig. 452, p. 103, and fig. 823, p. 215) : Fio. 911 Betol, naphthol salicylate, naphthalol, naphthol-salol, sali-naphthol, C17H12O3 ; m.p. 95° ; used for the same purposes as salol, but preferred by many in gonorrhoeic cystitis and articular rheumatism ; tasteless and odourless Alphol is the a-combination. COMPOUND ETHERS The same naphthol forms with benzoic acid a similar compound : 249 Fig. 912 Benzo-naphthol, ^-naphthol-benzoate, Ci^Hi^Oa ; m.p. (?) ; intestinal antiseptic ; splits up in the body into 6-naplith.ol, which passes into the intestines, and benzoic acid, which is carried away through the bladder partly as hippurio acid 250 OXYGEN-COMPOUNDS F. ETHER-ACIDS If we join an alcohol to the alkyl-part of a fundixmental aliphatic acid, we do not form a compound which has not been already mentioned ; we simply obtain a higher homologue of the acid. Take, for instance, methyl-alcohol and join it in the way mentioned to acetic acid, and propionic acid is formed. Fm. 913 Methyl-alcohol + acetic acid i) e> Propionic acid (fig. 669, p. 176) The result is different if we perform the operation on a hydroxy-aoid, having an alcoholic hydroxyl which can form an ether with another alcoholic hydroxyl. The process is in every respect analogous to ether-formation, p. 113, and the resulting compounds are therefore termed ether-acids. The aliphatic compounds are not very important, and it will be suflScient to illustrate a typical example : Fig. 916 O- Methyl-alcohol + glycoUio acid (fig. 691, p. 179) Methyl-glyooUio acid, methoxy-acetio or oxy-methyl- acetic acid (comp. p. 81), CjHeOs ; b.p. 206° ETHER-ACIDS 251 More important are the combinations of hydroxy-acids with phenols, phenol-ethers, &c., or hydroxy-cyclo-acids with alcohols. From glycollia acid and phenol : Pio. 917 Phenol-glyoollio aoid, phenyl-oxy-acetio aoid, CeHeOj ; m.p. 96° ; powerful antiseptic We have had another combination of the two compounds, an aromatic acid, mandelic acid (fig. 816, p. 213, where phenol was substituting a hydrogen of glycollic acid), possessing, it seems, no therapeutic properties. Erom para-hyd/roayy-benzoic acid (p. 216) and methyl alcohol, also derivable from anisic ald^e- hyde - Chloral, O2HCI3O ; b.p. 97°-7 272 HALOGBN-OOMPOUNDS It forms with water a hydrated compound having two hydroxyls attached to the same carbon- atom, one of the rare cases of this occurrence : Pio. 976 Fia. 977 -O- -# — O Chloral and water Chloralhydrate, C2H3CI3O2 ; m.p. 57° Bromalhydrate is an analogous compound with bromine instead of chlorine, OjHgBrgOj, b.p. 53°*5. Its therapeutic action is similar to that of chloral ; its hypnotic effect, however, is not so ■ marked. Used mostly as a sedative and antispasmodic in epilepsy, chorea, &c. Analogous to this are the chlorine-derivatives from butyr-aldehyde (fig. 543, p. 132), or croton- aldehyde (fig. 549, p. 133) : Fig. 978 Fio. 979 . t Trichloro-butyr-aldehyde, butylchloral, C4H5CI3O ; b.p. 164° -#— O Butyl-chloralhydrate, oroton-ohloralhydrate, CiH^ClsOs, ; m.p. 78° Hypnotic, ansesthetic, and sedative in trigemini neuralgia ; externally for toothache with equal parts of carbolic acid Chloral may be joined to glucose to form a glucoside-like compound : Fig. 980 Chloralose, OsHnCljOe ; m.p. 186° {Ber. xxii. p. 1050 ; CoDvpt. Rend. cxvi. 1893, p. 63) ; a more powerful hypnotic than chloral, but increases the irritability of the spinal cord. Another structure with ring formation, in which tri-ehloro-methyl and part of glucose form side-chains, has been suggested. An isomer, para-chloralose, m.p. 227°, has also been prepared (Compt. Bend, oxvii. p. 734) DERIVATIVES FEOM ACIDS- 273 Acid-derivatives Hydrogen-atoms in the alkyl-body (including closed chains) of the acids may, one after the other, be replaced by halogens ; carboxyl's hydrogen cannot be so replaced, whereas carboxyl's hydroxy! can. Prom ca/rbonic aoid (fig. 690, p. 179) is thus formed Fio. 981 Phosgene, carbon-oxy-ohloride, oarbonyl-chloride, CCljO ; a gas ; b.p. 8° It is formed in chloroform by exposure to light for several months, and is suggested as the probable cause of death during chloroform anaesthesia (Gh. & D. 1892, p. 221). This hypothesis is, however, not well supported, physiological researches having given contradictory results, disclosing also a certain connection between fatal cases and the amount of alkaloidal substances present in the urine (Dr. Lauder Brnnton's inaugural address at the meeting of the Pharmaceutical Society of Great Britain, October, 1893). Chloro-carbonic acid (chloroformiG acid), Cl-CO.OH, is carbonic acid in which one hydroxy] only is substituted by chlorine. It cannot be isolated, as it breaks up into hydrochloric acid and carbon dioxide ; nor have any salts been prepared, but several compound-ethers are known. From acetic acid : Fig. 982 Monochlor-acetic acid, C2H3CIO2 ; m.p. 63° Pro. 983 O- Diohlor-acetio acid, O2H2CI2O2 ; b.p. 191° Pig. 984 Triohlor-acetic acid, CaHClsOa ; m.p. 52°-5 Pig. 985 Trichlor-acetyl-cMoride CaCliO ; b.p. 118° All these compounds are caustics, some of them used for the removal of corns and warts. Erom aromatic acids we shall mention Pig. 986 Di-iodo-salioylic acid, C7H4IJJO3 ; m.p. 220° (decomp.) ; analgesic, antithermic, antiseptic, heart-paralysing 274 HALOGBN-OOMPOUNDS Future Nomenclature of Halogen-compounds The rules for numbering carbon-atoms in hydrocarbons are also applied to their substitution- products. In chains with no side-chains and no triple or double bindings the numbering commences at the end most proximate to a substituent, and when two substituents are placed equi- distantly from each end, the one is chosen where the substituent is of a higher order ; or, in the case of substituents of equally high order, the one which has the lowest atomic or molecular weight. Accordingly, chloral (fig. 975, p. 271) becomes tri-chlor-ethanal, chloral-hydrate (fig. 977, p. 272) 2 tri-chlor-ethane-l dial, butyl-chloral-hydrate (fig. 979, p. 272) 2:2:3 tri-chlor-lutwne-l dial, mono-chlor-acetic acid (fig. 982, p. 273) cMor-ethane (or ethanoio) add, &c. Part IX. S"ulphur Compounds Sulphur-coinpounds Index, ^ Chemical symbol, S. The next element which serves to form new compounds is sulphur. We meet here with an element that behaves towards other elements, as regards its power to combine with them, in a way different from what we have, as yet, seen of carbon, hydrogen, oxygen, and halogens. We have been led to believe that each of these elements has a certain number of valencies, no more, no less; and that these valencies are always in activity, must combine with some other valencies, and that a compound is not at rest, i.e. in a stable form, until the cravings of all valencies have in one form or another been satisfied. This is, however, truth with modifications. It is true as regards hydrogen in all its combinations. Hydrogen is a monad, and remains a monad under all circumstances that we know of. It is true as regards carbon in all its relations to hydrogen, provided we admit the theory of double and triple bonds as truths. It is true as regards oxygen in all its known combinations, and it is true as regards halogens in the combinations which we have as yet discussed. Before we go on with this subject it is desirable to explain what is understood by electro-positive and electro-negative bodies, not so much because I consider expressions which have been used for at least fifty years, unfamiliar, but that I seize the opportunity of presenting (in a popular and much condensed form) the latest views on molecules' and atoms' behaviour towards heat, electricity, and in solution. All bodies can exist in three states of aggregation — in the solid, liquid, or gaseous state — provided they do not decompose by heat. The molecules of a solid are all under the influence of each other ; they cannot move about as they like, each particular molecule being within the sphere of action of all its neighbours. In the liquid state, however, they can move about more freely, although they do not leave each other entirely, but wander about from one to another. In the gaseous state each molecule is beyond the attractive force of any other, and starts away along its own path, which is a straight one, until altered by its colliding with another molecule, or rebounding from some impassable boundary. In all these aggregates, even in the solid one, the molecules are moving about, and will on reaching the surface of the body exert a certain degree of pressure on the enclosing boundaries. In the case of solid bodies the particles are held together with so much force that scarcely any of them can escape, even if the enclosing medium — air, for instance — would allow their passage. It is like a ball fastened to a string being whirled round, and coming too near a window will manifest its power of pressure by smashing the glass, but without being able to gain its liberty through the aperture it has made, except when the string may, now and then, be cut by the broken glass. In liquids this bond is so much loosened that many of the particles coming to the surface can free themselves from the restraint of the others, and move away into space, i.e. they assume the conditions of the gaseous state (evaporation). We know that all bodies, with the exceptions mentioned, can exist in these three states of aggregation, and we know from daily experience that the conversion from one into another of these states is effected by adding or abstracting heat. But heat is motion ; so it appears intelligible 278 SULPHUE-COMPOUNDS enough that when we add motion to motion it will increase, and consequently lessen more and more the attracting bond between molecule and molecule. But it is not the molecules only that are moving ; the several atoms of which a molecule con- sists have a motion of their own, which is similarly affected by the motion we call heat. As soon as heat has made the molecules independent one of another, in other words converted the body into the gaseous state, the effect of heat begins to tell upon the atomic motion by increasing its speed, and thereby loosening, and at last breaking, the bond that holds them together, splitting the mole- cules gradually up into smaller and smaller fragments or groups according to the more or less complex nature of the compound, and finally into single atoms : this process is termed dissociation. The molecules in a gas have not all the same motion or heat, in consequence of their irregular collisions. When we measure the motion or heat by a thermometer it only gives us the average heat of those molecules with which it is in contact ; some may have a higher, others a lower tem- perature. Those which have the highest temperature commence first to break up, and gradually, as more and more heat is added, the others follow their example. Water, for instance, having been transformed by heat into gas, undergoes first chemical ex- change, forming molecules of oxygen and hydrogen. Fio. 987 Fis. 988 O — ©— O 1+ D -^ J 2(H20) = H2 + O2 + H2 and on further heating these molecules separate, forming a mixture of free atoms : PiQ. 989 9 + 9 H ®— • + — #— • + 9 + 9 At 3000° the separation of all water-molecules is accomplished ; therefore we know that no steam can exist above that temperature. In hydrocarbons much less heat is required to enable the hydrogen atoms to separate from the carbon than to make the carbon atoms themselves separate from one another. That is the reason of double bonds being formed so frequently at high temperatures. The temperature at which dissociation may be regarded as accomplished varies very much with the different compounds, some being dissociated at ordinary temperature (carbon monoxide and nitric oxide '), others at temperatures which we cannot produce, but are supposed to exist on the sun, where all elements may be considered present as free atoms until they, hurled away into space, cool sufficiently to form molecules, and fall down upon the sun, to be again dissociated, the process continually repeating itself and giving rise to those movements on the sun's surface which we com- pare to violent storms and cyclones, and to those phenomena which we describe as sun-spots, faculae, prominences, &c. The same sort of dissociation also takes place in solutions when solid bodies are dissolved in liquids, or even in other solid bodies, as they are in steel, glass, alloys, &c. The bonds between the molecules and atoms are so much loosened by coming into contact- with the dissolving body that one by one they tear themselves away from the rest and commence their wandering through the other body just like the molecules of a gas. It is, in fact, a perfect evaporation of one body into ' These compounds have a very low hoiling-point, somewhere about —200° (caibon monoxide's m.p. —199°), and it is probable that they in the fluid state double the number of atoms in the molecule. Carbon monoxide, for instance, is as a gas composed of one atom of carbon and one atom of oxygen, CO leaving two of carbon's valencies free. In the fluid state the molecule will probably consist of two such groups, = C = C = 0, when all the valencies are engaged ; similarly with nitric oxide, = N — N = 0. INTRODUCTION 279 another, just as a liquid voluntarily evaporates into the air. As a striking instance of these move- ments in solid bodies may be mentioned copper-plated zinc ; the copper gradually penetrates into the zinc and at last leaves the surface quite white as it was before it was coppered. We know that a molecule in a gas rushes about in all directions, frequently coming in contact with other molecules from which it rebounds, continuing its path in one direction until a fresh collision gives it a new one. But of course a certain proportion of them will, if the gas is enclosed in a vessel, reach and strike the wall of that vessel, and consequently exert a pressure on it. Exactly the same process takes place in a solution, a certain number of the molecules rushing about in a solvent, reach and strike the sides of the vessel in which it is contained. The pressure exerted by these impacts is styled the osmotic pressure, and, when measured by a suitable apparatus, has been found to be the same for different compounds when they are present in the same number of molecules, all other circumstances being equal. Consequently when we have ascertained the pressure of 342 grammes of cane-sugar (whose molecular weight we suppose to be known) in a litre of water, and find that 150 grammes of tartaric acid (whose molecular weight we suppose to be unknown) also dissolved in a litre of water exerts the same pressure, then, knowing 342 to be the molecular weight of the sugar, the molecular weight of tartaric acid must be 150. It has further been dis- covered that the freezing-point of a fluid is depressed to a certain degree when it contains in solution another compound, and the same law has been found to hold good in this case as in that of osmotic pressure, viz. that the depression of the freezing-point is the same for corresponding molecular weights of different compounds. This is used as a method of determining the molecular weight, and is known as Raoult's law. There are, however, a considerable number of exceptions to this law, compounds that depress the freezing-point twice or three times as much as they should do according to their molecular weight. In order to explain this fact the hypothesis has been propounded and generally accepted as correct, that these compounds dissociate in solution, and that consequently for each molecule in the compound there are two or three &c. fragments of it present. Common salt, for instance, which is composed of one atom of chlorine and one atom of sodium, would, dissolved in water, split up into its components. The effect of this on the freezing-point would therefore be doubled, and that agrees with the fact. It is, however, not to be understood as if sodium- and chlorine-atoms were swimming about without taking the slightest notice of each other, an apprehension capable of producing cold perspiration on a chemical brow ; on the contrary, there is an incessant joining and separating of the two elements' atoms, an unintermittent composition and decomposition of chloride of sodium. We may perhaps best picture the process to ourselves by thinking of a figure in certain dances called the grand chain, where ladies go one way and gentlemen the other, seizing alternately each other's right and left hands, but not letting go one hand before the next one has been taken hold of, continually changing partners without for a moment breaking the ring. Further it has been discovered that all the compounds which form the exceptions from Raoult's law behave differently from what all the compounds that follow the law do towards an electric current. The ends of the wires leading to and from a voltaic battery when dipped down in a vessel (the electrolytic cell) containing a liquid are termed electrodes. The one connected with the copper- or carbon-plate, the positive pole in the battery, is the a/node, the other connected with the negative zinc-plate is the kathode. If the vessel contains a substance that follows Raoult's law no current will go through the liquid, and everything' will remain just as it was before the electrodes touched the liquid. But if the vessel contains a liquid, or a solid in solution which forms an exception to that law, the current will pass through, and the liquid (electrolyte) will at the same time undergo decomposition (electrolysis). Suppose common salt (one of the exceptions) were dissolved in the water ; it would more or less, according to concentration and temperature, split up into free atoms of sodium and chlorine, running about in the water as already described. When now the electrodes are put down in the solution, the sodium-atoms nearest to the anode at the moment of closing the current will be loaded with positive electricity, with which they will swim over to the kathode, drop anchor, and discharge their cargo, which then returns to the battery through the kathode, leaving behind the sodium still at 280 DYAD SULPHUR-COMPOUNDS anchor. Atom upon atom arrive heaping up sodium at the kathode, each atom carrying a fixed load of ^ electricity ; therefore the quantity of electricity passed through an electrolytic cell can be determined by the quantity of metal deposited on the kathode (such meters are used for measuring the quantity of electricity supplied to houses; as the electricity is only carried through from one electrode to the other none of it is lost on its way through the electrolytic cell). Similarly, the chlorine-atoms are loaded at the kathode with negative electricity, which it carries to the anode, where it is forwarded to the battery, the chlorine-atoms remaining behind as did the sodium at the other electrode,^ always keeping in mind please ' the grand chain.' The fragments into which the original compoand is split up by dissociation are collectively termed ions, those congregating at the anode being called anions, those at the kathode kathions. The anions are said to have electro-negative, the kathions electro-positive character. The process itself is called electrolysis. We are now prepared to conclude our discussion of the valencies of elements, which we broke oflf after having remarked that hydrogen was under all circumstances a monad, carbon a tetrad (with one only exception, carbon monoxide), oxygen a dyad, and halogens monads, in all combinations hitherto discussed. But the halogens are only monads in their combinations with elements more electro-positive or less electro-negative than they themselves are ; towards oxygen, however, they may present one, three, five, or seven valencies, according to the circumstances under which they combine with that element. Similarly with sulphur. Towards electro-positive elements or groups it is a dyad with two valencies, but towards electro-negative bodies it shows, according to circumstances, four or six valencies.* We shall therefore have to consider the combinations of sulphur under different headings : first, those with positive bodies in which sulphur appears as a dyad ; secondly, those with negative bodies in which sulphur will be considered separately according to its tetrad or hexad nature. DYAD SULPHUR-COMPOUNDS Thio - compounds Index, -O— In its electro-negative character sulphur always appears as a dyad, and has such a remarkable resemblance to oxygen in its chemical behaviour that it may often be looked upon as replacing oxygen in its several compounds. All these are termed thio-compounds. Sulp]i-ur and Hydrogen In water, our very first oxygen-compound, sulphur may take the place of oxygen : Fig. 990 Sulphuretted hydrogen, H^S ; a gas ; present in sulphureous springs ' This is not strictly correct, as, in point of fact, neither sodium nor chlorine is to be found at any of the electrodes on account of a secondary decomposition, with which we shall not oompUoate the matter. ' Lately a sulphuric acid has been prepared consisting of one sulphur-atom and four oxygen-atoms ; it that is found to be correct, sulphur may have even eight valencies. THIO-ALOOHOLS AND ETHERS 281 TMo-alcolLols, or Mercaptans Also in alaohols (vide p. 67) sulphur may replace oxygen, giving rise to a series of compounds which have received the special name of mercaptans, other names being alkyl-sulphhydrates, thio-alcohols, and thiols. Examples are Fig. 991 Pig. 992 m &H ► — < ►— »o Bthyl-meroaptan, ethyl-hydrosulphide, OaHeS ; b.p. 36° Methyl-meroaptan, methyl-hydrosulphide, CH^S ; b.p. 6°, according to most authorities ; Beilst (i. p. 340) has 20°, and Weyl 148° (probably a misprint) The latter is the cause of the peculiar smell of urine after partaking of asparagus (Arch. exp. Pathologie, xxviii. p. 206), the former is one of the gases in the intestines The hydrogen in connection with sulphur may in analogy to . alcoholates (vide p. 109) be replaced by metals, the ensuing compounds being termed mercaptides. Sulphur can likewise replace oxygen in phenols (p. 92), forming thio-phenols or phenyl- mercaptans. TMo-ethers, or Alkyl- (phenyl-) sulphides These compounds correspond to the ethers (p. 113), and may be considered derivatives of them by substitution of sulphur for oxygen. Thus to methyl- and ethyl-ether (figs. 471 and 473, p. 113) correspond Fig. 993 Fig. 994 O— ■ w^ .. Q— o Thiacetic acid, CjHtOS ; b.p. 93° From ca/rbonic acid the following substitutions by sulphur are known, though most of them in derivatives only : Fig. 1000 Fig. 1001 D— o o-^ -^^— o o—i^ Fig. 1002 ^)— O Thioxy-carbo^io acid, carbonyl- Di-thioxy-carbonio acid, carbonyl- Tri-thio-carbonic acid, sulpho-carbonic thioxy-acid, CHsSO^ di-tbio-acid, CH^SjO acid, CH2S3 ; a brown oily liquid THIO-ALDBHYDES AND ACIDS 283 Fig. 1003 Pia. 1004 ■(D— K) Oxy-di-thio-oarbonio acid, OHjSaO Fio. 1005 Di-oxy-tMo-carbonic acid, CH2SO2 ; b.p. 161° ; oily liquid Tio. 1006 Carbon-oxysulphide, CSO ; a gas Oarbon-di-sulphide, CS2 ; b.p. 46° Many derivatives of these compounds are known, principally compound ethers (p. 231). The acid compound-ethers of oxy-cl/i-thio-ca/rbonio acid are known by the name of xanthic acids: FiQ. 1007 -0— o (Ethyl-) Xanthic acid, C3H5S2O; decomposes on slightly heating (25°); its potassium salt is used as a phylloxera-killei Similarly, sulphur can displace the oxygen-atoms in carbonic acid when this acid forms part of a/romatic com/pounds ; for instance, in benzoic acid. Fia. 1008 " Fia. 1009 Fm. 1010 B-Thio-benzoic acid, CtEsSO m.p. 24° and in salicylic add : /3-Thio-benzoio acid, CiHeSO crystals Pig. 1011 Di-thio-benzoic acid, C^HeSa ; an oily liquid ; easily decomposes Thio-salicylic acid, C7HeS02 ; brown amorphous mass 284 DYAD SULPHUE-COMPOUNDS In hydroxy-benzoic acids (p. 216) the oxygen in the hydroxyls may likewise be replaced by sulphur ; thus we know Fio. 1012 Meta-thio-hydroxy-benzoic acid, CfHeSOj ; m.p. 146° Two of these can combine by eliminating the sulphurs' hydrogens : Fig. 1013 Meta-di-thio-hydroxy-benzoio acid, CiiHioSaOi ; m.p. 242' A similar compound may be (theoretically) derived from dir-hydroxy-benzoic acids. We know two of them, though the exact position of the sulphur-group has not been ascertained. For the sake of illustration, we represent one of them, analogous to the preceding one. CLOSED CHAINS Fia. 1014 285 Di-thio-Balicylio aoid, Ci^HjoS^Oe ; a thick oily liquid. The other acid is an isomer ; the sodium salts of these two acids are distinguished, one as No. I. and the other as No. II. ; the mixed salts have the trade name dithion, which is used as an antiseptic in articular rheumatism and gonorrhoea. Thioform is the analogous basic bismuth salt recommended in many cases as a substitute for iodoform (Bepert. d. Thierheilk. vi. 1893). Thiopheiie We have seen oxygen helping to close a chain in furfurane (fig. 941, p. 260) and pyrone (fig. 945, p. 260). Sulphur can perform the same task : Fig. 1015 Thiophene, C^HtS ; b.p. 84° ; present in coal tar Thiopheneisa compound that very much resembles benzene. Its combination with two atoms of iodine thiophene-di-iodide, has been recommended as a substitute for iodoform, being non- poisonous {Wiener med. Presse, Ph. 0. xxxiv. p. 112). 286 TETRAD SULPHUR-COMPOUNDS The heat of combustion not indicating any double-bonds in thiophene, diagonal bonds have here too been suggested, Pia. 1016 analogous to those proposed for benzene, fig. 290, p. 55 j what is said there about this sort of bonds holds good here too. A hexagonal form has also been prepared : FiQ. 1017 Penthiophene, CjHeS ; penthiophene has not yet been isolated, but a methyl-derivative is known (Die Thicyphengrwppe, by V. Meyer) The methylene-group in para-position has also been substituted by sulphur in the compound biophene, O^H^Sj, b.p. 170°. TETRAD SULPHUR-COMPOUNDS Index, Sulphines If one of the valencies is occupied by an electro-negative mono-valent element or group (e.g. iodine), four, altogether, of the valencies of sulphur will be excited to activity, so as to admit the connection of three hydrocarbons instead of two in alkyl-sulphides (p. 281) : Fig. 1018 Tri-methyl-sulphine-iodide, CaHgIS ; crystals This compound behaves like a salt ; but if iodine is replaced by hydroxy], the product tri-methyl- sulphine-hydroxide is then a powerful base, as strong as caustic potash. SULPHINBS, OXr-SULPHINES, AND SULPHINIO ACIDS 287 Oxygen-compouiids of Sulphur Oxygen and sulphur unite in many proportions, sulphur acting sometimes as a tetrad, sometimes as a hexad. We have not to do with all of them in organic chemistry, and only those with one, two, three, or four atoms of oxygen will be spoken of here. OXY-SULPHINES AND SULPHINIO AOIDS As a tetrad, sulphur can combine with one oxygen atom, leaving the two remaining free valencies to combine otherwise. The radical of these compounds is termed Fig. 1019 Oxy-sulphine, SO If both free valencies are united to carbon-atoms the compounds are known as sulphine- oxides or snlphoxides; if only one valency is united to a carbon-atom and the other to a hydroxy 1, we call the compound asulphinic acid. If both valencies are connected with hydroxyls, it is termed symmetric sulphurous acid. Oxy-sulphine, being a radical, does not, of course, exist in the free state ; sulphinic acid and symmetric sulphurous acid have not themselves been isolated, being converted into sulphurous anhydride. They are all known chiefly through their derivatives or as salts. Some of these are Sulphine- oxide's Derivative Pig. 1020 Di-methyl-Bulphine-oxide, di-methyl-sulphoxide, C^H^SO ; an oily liquid Sulphinic Acid's Derivatives Fig. 1021 Ethyl-sulphinio acid, OaHsSOa ; syrupy liquid 288 TETRAD SULPHUR-COMPOUNDS Fio. 1022 Benzene-sulpliinic acid, CgHeSOa ; m.p. 83° Some authorities look upon sulphur in these compounds as a hexad, and place the oxygens on each side of the sulphur in the form of siilphone (fig. 1029) and the hydrogen in direct connection with sulphur. Symmetric Sulphurous Acid's Derivatives Sulphurous acid does not exist in the free state, but is supposed to be present in derivatives in either of the two following structurally different forms : Pig. 1023 Fig. 1024 Asymmetrical sulphurous acid, SHjOs Symmetrical sulphurous acid, SHjOg It assumes in its combinations such form as is best suited to the circumstances. But both forms when liberated lose a molecule of water, and are converted into sulphurous anhydride. Fig. 1025 Sulphurous anhydride, sulphur dioxide, SOg ; a gas The process is analogous to that of carbonic acid, being converted into carbon dioxide (fig. 711, p. 184). In the first form sulphur is a tetrad ; in the second it is a hexad, and therefore not to be dealt with just now. The symmetrical acid's derivatives are characterised by their instability. They form neutral and acid compound-ethers (p. 231), the latter being incapable of existence in the free state, but a potassium salt is known ; also some neutral ethers. They are all readily saponified by water alone. Fig. 1026 Ethyl-sulphurous acid, C^HeSOa Ethyl-sulphite, C^HioSOs ; b.p. 161°. Compare the structure qf the compound ethers of asymmetrical sulphurous acid (fig. 1054, p. 295) SULPHONB-OOMPOUNDS 289 HBXAD SULPHUR COMPOUNDS Fia. 1028 Index, — 0/- Tlie hexad sulphur unites with two atoms of oxygen, leaving two free valencies at liberty to combine with two mono-valent radicals. This combination of sulphur and oxygen is spoken of as a radical, and is termed sulphuryl or Bulphone: Fia. 1029 Sulphuryl or sulphone With carbon-atoms attached to both free valencies the derivatives are termed sulphones; with a carbon-atom on one side and a hydroxyl on the other they are styled sulphonic acids; with a hydrogen-atom on ojie side and hydroxyl on the other it is asymmetrical sulphurous acid; and with hydroxyls on hoth sides it is sulphuric acid. Fia. 1030 Dimethyl-sulphone, OaHoSOj ; m.p. 109° Fio. 1031 Fio. 1032 Methyl-sulphonic aeid, CH4SO3 ; Asymmetrioal sulphurous syrupy liquid j decomposes acid, SH2O3 ; does not above 130° exist in the free state Fig. 1033 Sulphuric aeid, SH2O4; b.p. 888° SulplLone Compounds Sulphone itself is a di-valent radical ; when we join a hydrocarbon to one of its two free valencies, the product is a mono-valent radical : FiQ. 1034 FiQ. 1035 Methyl-sulphone, CH3SO2 Ethyl sulphone, C2H5SO2 290 HEXAD SULPHUR-COMPOUNDS These radicals may be affixed to many hydrocarbons and their derivatives, whether with open or closed chains. One that has gained much notoriety is propane, through having two of its hydrogen- atoms replaced by ethyl-sulphone : Fig. 1036 O^ H-O -O G— <►— O 0-Hh- O Snlphonal, di-methyl-di-etliyl-sulphone-inethane, CjHieS^Oi ; in.p. 125° ; an excellent hypnotic Several efforts have been made to improve upon sulphonal by replacing one of the methyls by ethyl (trional) or both methyls by ethyls (tetronal), or by adding a third ethyl-sulphone to sulphonal (tri-ethyl-sulphone-methyl-methahe), but without success. Also substitution of one or more hydrogen-atoms by chlorine has been tried with the same result. Sulphonyl Oompounds When a hydroxyl is added to one of sulphone's free valencies we have the mdno-valent radical of Bulphonic acid, sulphonyl: Fig. 1037 Sulphonyl, SHO3 When a hydrogen is added on the other side, the hypothetical sulphurous acid (asymmei/rical) is formed. Fia. 1038 -@— ^ Asymmetrical sulphurous acid, SH2O3 The radical of sulphonic acid can be joined to hydrocarbons, both with open and closed chains, or their derivatives, forming acids (sulphonated). SULPHONYL-COMPOUNDS 291 Derivatives from Open Chains FiQ. 1039 Methyl-sulphonio acid, CHiSOa ; syrupy fluid ; decompoaes ou heating Fia. 1040 Ethyl-Bulphonio acid, CaHeSOg ; deliquescent crystalline mass ; decomposes at a high temperature, and is not saponifiable (compare the structure of ethyl-sulphurous acid, fig. 1026, p. 288, which, being an ether, is saponi- fiable) Two or three sulphonic acid radicals may join the same carbon in these hydrocarbons : Fio. 1042 Fia. 1041 Methyl-di-sulphonio acid, CH^SaOa ; deliquescent crystals Methyl-tri-sulphonio acid, CH^SaOg ; crystals As a derivative from alcohol or glycol (fig. 364, p. 76) may be considered Fig. 1043 Isethionio acid, hydroxy-ethyl-sulphonio acid, OaHeSOi ; deliquescent crystals Derivatives from Benzene While the radical of sulphonic acid is introduced into the open-chain compounds with some difficulty, or at least by a roundabout way only, it is characteristic of compounds with closed chains that they join the same radical most easily, and as directly as possible, by being treated with sulphuric acid. Consequently a great number of these compounds exist of which we shall mention a few. V 2 292 HEXAD SULPHUR-COMPOUNDS Fia. 1044 Phenyl- or benzene-solphonic acid, CeHaSOs ; m.p. 40° Benzene will also combine with two or three sulphonic acid-radicals, but does not seem willing to accept more than three, although some derivatives will take four — which is their present limit. Fig. 1045 Aseptol, sozolio acid, ortho-phenol-snlphonio acid, CeHsSO^; disinfectant and antiseptic, more powerful than carbolic acid or salicylic acid On heating, the hydroxyl leaves its position and exchanges places with the hydrogen-atom in para-position (intramolecular change) : Fia. 1046 Para-phenol-Bulphonio acid, CoHoSO^ ; syrupy liquid SULPHONTL-OOMPOUNDS 293 Sozal is the aluminium-salt of this acid (two atoms of aluminium engaging six molecules of the acid). Clinical and bacteriological experiments do not agree as to the value of this antiseptic. Two hydrogens in the benzene-ring may be displaced by iodine-atoms : EiG. 1047 Sozoiodol, di-iodo-phenol-iJ-sulphonic aoid, CeHJaSO* The acid itself is not employed for medicinal purposes, but its salts have found extensive use. The potassium- and sodium-salts (the metal replaces the hydrogen-atom in the sulphonio radical) are used as non-poisonous antiseptics in obstinate diseases of the skin, chronic catarrh of the nose, gonorrhoea, syphilis, cancer, rheumatism, &c. ; salts with mercury, zinc, aluminium, magnesium, ammonium, lithium, silver, lead, &c., are in use. When another hydroxyl is added to the above we have Pig. 1048 Piorol, di-iodo-resoroin-sulphonio acid, CeHJaSOj ; the potasBium salt is used as an antiseptic 294 HEXAD SULPHUE-GOMPOUNDS A'C/resol-derivative ia Fia. 1049 i)-Cresol (p. 95) -o-sulphonio acid, CjIIaSOi ; m.p. J?our isomeric acids are structurally known (OH3 : OH : SHO3, 1:2:5, 1:2:4, 1:4:2, and 1:4:3), besides some others, the structures of which have not yet been ascertained. They are all used as disinfectants. Acidum sulpho-carbolicum orudum is made by treating crude carbolic acid with sulphuric acid. The crude carbolic acid consisting chiefly of cresols, the product will of course be mainly a mixture of different sulphonated cresQls, As, however, these too are powerfal disinfectants, it makes practically no difference. Derivatives from Naphthalene Fig. 1050 Pia. 1051 Naphthalene a-sulphonio acid, CjoHsSOa ; m.p. 90° ;3-Naphthol a-Bulphonic acid, croceio acid, GioHsS04 ; decomposes on heating; its neutral calcium salt has recently been introduced by the name of asaprol as an antiseptic Seven isomeric yS-naphthol sulphonic acids are known. Alumnol is the aluminium salt of yS-naphthol-di-sulphonio acid: it is an astringen^ can stop tears to any extent, and is therefore used in ophthalmic practice ; also in gynseoologic and dermato- logic cases, and in otorrhoea (PA. 0. xxxiii. p. 697). SULPHONYL-OOMPOUNDS 295 STilphonyl's Oombinations -with. Acids Fig. 1053 Fio. 1052 Sulpho-aoetio aoid, C2H4SO5 ; m.p. 62° ; strong di-basio acid ; may be considered a combination of sulphonio aoid with either acetic acid less H^, or glycollic acid less H^O o-Mono-sulpho-benzoic acid, C7H9SO5 ; m.p. 240' decomp. ; mother-substance of the sweet saccha- rine (fig. 1308, p. 368) The sulphonic acids, like other acids, form compound ethers ; Fig. 1054 Ethyl-sulphonio ethyl-ether, C4H10SO3 j b.p. 213°- Compare the structure of the compound ethers of symmetrical sulphurous acid (fig. 1027, p. 288) Experience has taught us that the introduction of sulphur, in one form or the other, into various compounds produces therapeutically beneficial effects. Thus a very ancient remedy was linseed oil, in which sulphur had been dissolved by heating. More recently natural products have been found containing a large percentage of sulphur, and these have been utilised for the same purpose; prominent among them is a bituminous mineral, found somewhere in the Tyrol, called stinking stone, we may safely suppose, from the smell of it : it consists mainly of fossilised remains of fish from former ages. The destructive distillation of this bitumen yields a distillate separating into two oily layers, the lighter of which, purified by redistillation, is rich in sulphur (2-5 per cent.), but its constitution is unknown. This light oil is sulphonated by treating with sulphuric acid, after which it is neutralised with ammonia (formerly soda was used) and given the name of ichtyol. The acid is said to be dibasic, and its empirical formula to be OjjHgeNjSgOg (Monatsh. f. pr. BerTnat. ii. p. 257), thus containing about 16 per cent, sulphur; no doubt it is a mixture of several thio-, sulphone-, and sulphonic compounds. It is a tar-like substance of herb-like odour. The raw oil is insoluble in water, and the object of snlphonatiag (as in most other cases where this operation is performed) is to make it soluble. A general characteristic of sulphonic acids (except those with long side-chains), and especially their salts, is their solubility in water, even when the mother-substance is quite insoluble. Ichtyol is partly soluble in water, entirely so in alcohol-ether. It is used in psoriasis, eczema, and articular rheumatism, internally for catarrh of the stomach and lungs. Of course, the success of ichtyol has called forth several attempts to displace it by artificial products. Thiol (Ichtyolum germanicum) is one of them. It is prepared from the brownish paraffin- or gas-oils by first heating them with sulphur (10 per cent.) to form thio-compounds ; afterwards. 296 HEXAD SULPHUR-COMPOUNDS treating them with sulphuric acid, producing sulphonic acids, neutralising with ammonia, and con- verting them at last by evaporation into a form of either fluid or dry extract. Tumenol is prepared from bituminous oils (sp. g. 0'86-0-89), from which phenols and acids have been removed by caustic soda, and bases by diluted sulphuric acid. The purified oil is then sulphonated; according to the degree of sulphonation, tumenolsulphone or tumenolsulphonio acid is obtained. Thus tumenol is not, like thiol, first sulphuretted (heated with sulphur to form thio-compounds), and contains for that rsason less sulphur. It is a dark syrupy fluid, and is recom- mended for running forms of eczema, prurigo, and pruritus. Thiolin is linseed oil, first sulphuretted, then sulphonated and neutralised with soda or potash. Thilanin is sulphuretted (but not sulphonated) lanolin. Polysolve, solvin, may be prepared from olive-, almond-, castor-oil, &c., by treating them with sulphuric acid and neutralising with potash, soda, or ammonia ; a soap-Uke fluid, dissolves sulphur, iodoform, camphor, metal-salts, &c., and is itself soluble in water, benzin, carbon disulphide, ether, and chloroform. Sulplmric Acid When sulphone (fig. 1029, p. 289) is joined by two hydroxyls, one on each side, we have sul- phuric acid. Fio. 1055 . Sulphuric acid, SHaOj ; b.p 338° The chief part it plays in organic chemistry, as regards structures, is as one of the components in neutral, and acid compound ethers, combining with alcohols and phenols by separating one or two molecules of water. Thus with ethyl-alcohol it forms Pia. 1056 Fia. 1057 Ethyl-sulphurio acid, sulpho-vinio acid, CaHeSOi ; syrupy fluid ; decomposes on heating ; the sodium salt is used as a cathartic Ethyl-sulphate, CiHioSOi ; b.p. 208° Ethyl-sulphuric acid is formed when alcohol and sulphuric acid are heated together. Ethyl- Bulphuric acid when heated with alcohol forms ethyl-ether and sulphuric acid : SULPHUEIO AOID-OOMPOUNDS 297 FiQ. 1058 Fio. 1059 (» O O 6 Ethyl-sulphuric acid and alcohol, one molecule of each = Ethyl-ether {vide fig. 473, p. 113) and sulphuric acid The metliod of preparing ether, now upwards of 150 years old, is based upon this reaction. The molecule of sulphuric acid separated wiU form ethyl-sulphuric acid when a fresh molecule of alcohol is added, and will as such again form ether and sulphuric acid as long as fresh alcohol is added. In this way an unlimited quantity of alcohol would be transformed into ether by the same quantity of sulphuric acid but for the fact that the formation of ethyl-sulphuric acid is always accompanied by separation of one molecule of water. Fio. 1060 Fio. 1061 9 a 6 Ethyl-alcohol and sulphuric acid -@ — O Ethyl-sulphuric acid and water The mixture becomes therefore at last so diluted that the sulphuric acid can form no more ethyl- sulphuric acid, which state will be accelerated by the fact that alcohol is never free from water ; therefore water from this source also is constantly being added to the mixture. Amongst the phenyl-ethers may be mentioned Fia. 1062 Fhenyl-sulphurio acid, CgHeSO^ 298 NOMENCLATURE OF SULPHUR-GOMPOUNDS The free acid decomposes almost immediately into phenol and sulphuric acid. The sodium-salt is used as an antiseptic for gonorrhcBa. The potassium-salt is found in human urine ; if it is heated to 150° it is by intramolecular change transformed entirely into potassium^-phenol-sulphonate, the sulphonyl-part of the sulphuric acid exchanging places with the hydrogen in para-position. Fia. 1063 Potassium-p-phenol-sulphonate (vide fig. 1046, p. 292) Future Nomenclature of Sulphur-compounds Mercaptans receive the name of thiols ; thio-ethers or sulphides form their names, in analogy to ethers, by placing f/ito, or in case of disulphides dithio, between the names of the hydrocarbons. Thio-aldehydes and thio-ketones become thiols and thiones, and acids have their names formed, according as sulphur substitutes the singly or doubly bound oxygen, by the suffixes thiolic add and thiordo acid; when both oxygens have been substituted they receive the suffix thion-thiolio acid. Sulphones have sulphone placed between the names of the hydrocarbons. Old Nomenclature Methyl-mercaptan Ethyl-mercaptan Ethyl- sulphide Ethyl-disulphide Thialdehyde Thioxy-carbonic acid Di-thioxy-carbonic acid Tri-thio-carbonic acid Oxy-di-thio-carbonic acid Di-oxy-thio-carbonic acid Di-methyl-sulphone Sulphonal 991, p. 281 992, p. „ 994, p. „ 996, p. „ , 997, p. 282' ^..g. 1000, p. , (fig. 1001, p. „ , (fig. 1002, p. „ ; (fig. 1003, p. 283: (fig. 1004, p. , (fig. 1030, p. 2L_^ (fig. 1036, p. 290) (fig- (fig- (fig- (fig- (fig- (fig. New Nomenclature Methane-thiol Ethane-thiol Ethane-thio-ethane Bthane-di-thio-ethane : Ethane-thial Methane-thiolic acid Methane-di-thiolic acid Methane-thion-di-thiolic acid Methane-thion-thioHc acid Methane-thion-di(oic) acid Methane-sulphone-methane Propane-2 : 2 di-sulphone-ethane The other classes of sulphur-compounds are not mentioned, and their nomenclature can scarcely be formed from the above rules. Part X. Nitrogen Oompoiinds Nitrogen Oompounds FiQ. 1064 Index, ^ Chemical symbol, N The next element with which to form new compounds is nitrogen, and the variety which this element is capable of producing is nearly inexhaustible. Like sulphur, its valencies are varying in number, but unlike that element, the valencies of which were always even numbers, six, four, or two, those of nitrogen are always an uneven number, five, three, and perhaps one. It can combine equally well with electro-positive and electro-negative bodies, forming very strong bases or acids, and can replace carbon-atoms in closed chains. We shall first mention the combinations of NITRO&EN AND OXYGEN of which there are several ; but only those with either one, two, or three atoms of oxygen are of importance in organic chemistry, forming acids when hydrogen enters into the radical. Hypo -nitrous Acid The first of the oxygen-combinations, that with one atom of oxygen, hypo-mtrous acid, is probably a double molecule. Fio. 1065 Hypo-nitrous acid, N2O2H2 ; decomposes on being isolated It forms salts and ethers. Only one of the latter (dA-azo-ethoxaTie) is known so far. Joining other compounds, where only one valency is ofiered for its accommodation, it seems able to split up into two molecules, it conforming to circumstances by a re-arrangement of its structure : Fia. 1066 Pis. 1067 of which the radical is Two molecules of hypo-nitrous acid Nitrosyl Thus, dropping a hydrogen-atom enables it to enter into direct union with a carbon-a^om in benzene-compounds with one free valency (aliphatic combinations of this sort are exceptional). 302 NITROGEN-COMPOUNDS These compounds are styled min-oso-oompounds to distinguish them from the oxknes, which may also be looked upon as formed from hypo-nitrous acid in the following way : When two valencies of a carbon-atom are available, the double molecule of hypo-nitrous acid simply divides itself into two di-valent radicals : Fia. 1068 Hydroximide, NOH the two free valencies joining the carbon-atom's valencies. These compounds are termed oximes (contracted from hydroximide or 6ximide). As the formation of them in this way is purely theoretical they will presently be considered a little more fully under Nitrous Acid and Hydroxylamine. Nitrons Acid The next combination is one atom of nitrogen and two of oxygen. Like the previous acid, and like sulphurous acid (p. 288), it seems capable of arranging itself into two structural forms, in one appearing as a triad, in the other as a pentad. Fig. 1069 Fio. 1070 Nitrous acid, NOaH ; decomposes easily when slightly warmed Salts of this acid are formed by metal replacing the hydrogen, just in the usual way. But all metals do not assert their influence upon the acid radical in the same degree ; some, e.g. alkali metals, are quite content to come into contact with the nitrogen, through the intervention of the oxygen, by replacing the hydrogen-atom of hydroxyl (fig. 1069, above) ; but this does not satisfy the noble silver ; it wants to come so near the nitrogen as to actually shake hands, and the acid has to comply by arranging things a little differently (fig. 1070, above). Therefore derivatives of the acid with such a structure, as in the silver-salts, are different from those of alkali salts. We shall study the latter a little first. As will be seen, we can make two radicals out of the nitrous acid, 1, by r amoving the hyda-oxyl: Fia. 1071 Nitrosyl, NO when we have a mono-valent radical the substitution-products of which are the same nii/roso-comr- pounds as produced from hypo-nii/rous acid (p. 301) ; and 2, by removing the doiibly-bound oayygen : Fi9. 1072 Hydroximide, NOH when we have a di-valent radical whose substitution-products are oximes (sometimes also termed iso-nitroso-compounds) mentioned above. NITROUS AOID-COMPOUNDB 803 As said before, we have not succeeded in combining nitrosyl with any alipbatic compound, except in one or two cases to be subsequently (pp. 305 and 335) mentioned, but we know several aromatic nitroso-compounds with nitrosyl as substituent, either in the benzene- or in the aliphatic-part of the substance, but none of them is of sufficient interest for our purpose. Oximes form a large series of compounds, but the greater part of them is the product of the action of hydroxylamine (a compound we are coming to, p. 380) upon aldehydes and ketones. As an example of oximes formed by nitrous acid we may mention iso-nitroso-acetone : Fio. 1073 Fig. 1074 Acetone + nitrous acid {vide fig. 666, p. 138) O— ®— O Iso-nitroso-acetone + Water C3H5NO2 ; m.p. 65" Nitrous acid will with alcohols form compound-ethers when it has the structure we are now discussing. For instance : Fia. 1075 -#— — ®— ^^ o ^ ] 6 FiQ. 1076 Alcohol + nitrous acid Ethyl-nitrite, sweet spirits of wine, saltpetre-ether, C2H5NO2 ; b.p. 18° ; spiritus setheris nitrosi is its alcoholic solution mixed with some by-products from its preparation, such as aldehyde &o. ; a mild irritant Fia. 1077 6 o — tH-O o Iso-butyl-nitrite, O^HgNOa ; b.p. 67° ; used for inhalation in asthma, angina pectoris, 4o. Four isomers are known 804 NITROGEN-COMPOUNDS Fi8. 1078 o O o O— C5 — «H-0 Iso-amyl-nitrite (amyl-nitris, PA. J5.), O5H11NO2 ; b.p._ 94-99°; produces an expansion of the blood-vessels and a diminution of the controlling power of the contractile muscles ; very poisonous ; is employed internally and by inhalation in angina pectoris, asthma, epilepsy, &o. The amyl-alcoliol from whicli it is prepared does not, as a rule, consist entirely of the pure iso- compound ; therefore a/myl nitris is, as a consequence, slightly mixed with some of the isomeric amyl-nitrites. Nitrous acid of the structure (fig. 1070, p. 302), which it has in the silver-salt, forms another series of compounds differing from the preceding ones by not being comppund ethers : they are distinguished as nitro-compounds, and the radical of nitrous acid in this form is termed nitro- group. Thus from methyl-alcohol is formed Fia. 1079 Fig. 1080 Methyl alcohol + nitrous acid Hitro-methane, nitro-oarbol, CH3NO2 ; b.p. 101° ; the salts are explosive The alcohols and the acid are practically not employed for preparing these compounds ; methyl iodide (fig. 948, p. 265) and silver nitrite are used for the purpose. In these compounds iodine replaces the hydroxyl in the alcohol, and silver the hydrogen ia the acid, the process going on as illustrated above, only that silver-iodide is separated instead of water. For the sak.e of our theory, mention should not be omitted of the fact that this process is only carried out thoroughly by methane. The higher homologues deliver, besides nitro-compounds, also the compound-ethers ; and the higher the homologue the more of the latter. A satisfactory expla- nation of this fact is still wanting. The nitro-group can also substitute the other hydrogen-atoms in the methane group; for instance : Fia. .1081 Fig. 1082 s+s Tri-nitro-methane, nitroform, OHNaOe ; m.p. 15° ; explosive Tetra nitro-methane, nitro-oarbon, CNiOg ; m.p. 13'^; b.p. 126° NITROUS AOID-COMPOUNDS 305 The nitro-group imparts such an electro-negative charactei' to the carbon-group as to make it a strong acid as long as there are hydrogen-atoms attached to the same carbon-atom. Such hydrogen-atoms, or at least two of them, are therefore replaceable by metals, forming salts. If all the hydrogen-atoms are replaced by nitro-groups the compound loses its acid character and becomes neutral. Thus nitro-, di-, and tri-nitro-methane are strong acids, but tetra-nitro-methane is neutral. It is the same if some of the hydrogen-atoms are replaced by halogens. Although the hydro- carbon is made electro-negative by the presence of the nitro-group, it does not for that reason object to its remaining hydrogens being replaced by such electro-negative elements as the halogens ; thus we have Fia. 1083 Fia. 1084 Bromo-nitro-methane, CHjBNOa ; b.p. 143° a strong aoid Tri-ohloro-nitro-methane, ohloropiorin, nitro-ohloroform, OOlaNOa ; b.p. 112° ; neutral compound Similar compounds have been prepared from some of the higher homologues of methane. It is into these nitro-compounds that the radical nitrosyl has been successfully introduced ; no other compounds of the aliphatic series have been found willing to combine with that radical, as mentioned p. 303. It attaches itself to the same carbon-atom that holds the nitro-group, and the ensuing products are termed nitrolic acids when both are combined with the methyl-group of an alcohol radical (primary alcohols), but when combined with a methylene-link (secondary alcohols) they are neutral bodies for the reason stated above, and are called pseudo-nitrols. The derivatives from propane or propyl-alcohol and iso-propyl-alcohol (figs. 338 and 339, p. 70) will serve to make this better understood : Fia. 1085 Fro. 1086 <;> Propyl-nitroUo-aoia, CaHsNjOa ; m.p. 60 ; an acid, because it has a hydrogen-atom connected with the same carbon- atom as the nitro- and nitrosyl-groups Propyl-pseudo-nitrol, CaHeNaOa; m.p. 76°; (deoomp.) a. neutral body, because no hydrogen-atom is connected with the same carbon-atom as the nitro- and nitrosyl-groups The solutions of the nitrolic salts have a dark red colour, whereas the solutions of pseudo- nitrols are dark blue. This reaction is taken advantage of to determine whether an alcohol is primary, secondary, or tertiary, as nitrolic compounds are derived from primary, and pseudo-nitrols from secondary alcohols. Tertiary alcohols cannot form these derivatives, as they have no spar© room for the nitrosyl (vide fig. 335, p. 69), and consequently give no colour-reaction in this way (Liebermcmn's reaction). 306 NITROGEN-COMPOUNDS Some chemists are of opinion that the nitrolie acid has in its structure hyd/roximide (fig, 1068, p. 302) instead of nitrosyl ; consequently propyl-nitrolic acid would have this structure : Fio. 1087 I i Propyl-pseudo-nitrol cannot have hydroximide in its structure, as there are not suflBcient valencies and no hydrogen available. It seems more reasonable to give these two compounds analogous con- structions ; the nitrosyl-structure is perhaps, therefore, preferable. There are a great many more nitro-compounds which may be theoretically derived from nitrous acid in a similar way ; but as all of them can theoretically be equally well derived, and practically are derived, from nitric acid, they will be mentioned under that head. Nitric Acid Nitrogen is penta-valent in nitric acid, uniting with three atoms of oxygen, one of which forms hydroxyl with a hydrogen-atom ; consequently its structure may be thus depicted : Fig. 1088 Nitric acid, NHO3 ; b.p. 86° Nitric acid does not readily form nitro-compounds direct from the single-linked hydrocarbons of the aliphatic series ; a couple or so, formed from' hydrocarbons, with double bonds appear to be known, and a few secondary nitro-compounds have recently been prepared from the normal saturated hydrocarbons {Ber. xxv. Bef. p. 108 ; see also xxvi. p. 129), else it has ordinarily no action upon them. The aromatic hydrocarbons, however, and their derivatives are easily reacted upon by nitric acid, their hydrogen-atoms forming water with the acid's hydroxyl, and the nitro-group taking the place of the hydrogen : Fio. 1089 Fia. 1090 &i— #— e Benzene and nitric acid Nitro-benzene, essence of mirbaji, artificial bitter- almond oil, CaHsNOs ; b.p. 210° NITRIC AOID-OOMPOUNDS 307 Nitro-benzene is used in large quantities for the manufacture of colours, also in perfumery, on account of its odour being very like that of bitter-almond-oil (vide fig. 554, p. 134). Poisonous. As many as three, but not more, nitro-groups have been thus introduced into benzene and its derivatives. Fio. 1091 Syimnetrical tri-nitro-benzene, CeE^NsOa ; m.p. 121° When an iso-butyl (fig. 58, p. 13, also Table, p. 82) is placed in para-position to one of the nitro-groups and methyl in ortho-position, we obtain a compound with a strong musk-like odour. Fio. 1092 Xonquinol, artificial musk, tri-nitro-butyl-toluol, CnHiaNjOe ; m.p. 96° ; the commercial product is a mixture of 10 per cent, of this compound and 90 per cent, of acetanilide Though tonquinolis only two or three years old it has already found a rival, which can do things better, can dissolve itself in water, which tonquinol can not. This opposition-compound consists of a benzene-ring in which the hydrogen-atoms are replaced by 1, two methyls (ayylene, p. 44) ; 2, one iso-butyl ; 3, a sulphonyl (fig. 1037, p. 290) ; and 4, a nitro-group. The different positions of these radicals in the benzene-ring have not been ascertained : its systematical name would be wU/ro-sulpho- iso-butyl-xylene ; it does not appear to have received a trade name yet {Ph. G. xxxiii. p. 80). X 2 308 NITROGEN-COMPOUNDS Of nitro-compounds from other benzene-derivatives we shall call attention to two : Fia. 1093 Fia. 1094. o-Di-nitro-oresol, CijHeNaOs ; explosive Pierio acid, tri-nitro-phenol, C0H3N3O7 ; yellow crystals ; m.p. 122°-5 ; crystals ; m.p. 85° a yellow dye ; explosive ; the chief constituent in the French explo- sive melinite The potassium salt of the o-di-nitrol-cresol (the metal replaces hydrogen in hydroxyl) is an excellent insect-killer, and mixed with equal parts of soap is, under the name of antinonnine, used for freeing plants from all sorts of noxious insects, wood from dry-rot (Merulius poh/poncs, hametes, Sue.), and for killing ,rats and mice. Also in scabies it is said to be an effective remedy. FTom phenyl prcypiolio acid (fig. 822, p. 215) we have an ortho-nitro-compound : Pig. 1095 Ortho-nitro-phenyl-propiolic acid, C^HsKOi ; crystals, deoomp. at 155° Boiled with water this acid looses its carboxyl, and is turned into a hydrocarbon : Pig. 1096 Ortho-nitro-phenyl-acetylene, CgHsNOa ; m.p. 81° ; compare fig. 291, p. 55 Through copper, which is a dyad, two molecules of the above hydrocarbon are joined, the copper replacing the hydrogen in each of the two acetylenes ; and then eliminating the copper by oxidation we get the two nitro-phenyl-acetylenes directly united : NITEIO AOID-COMPOUNDS FiQ. 1097 809 Di-nitro-di-phenyl-di-aoetylene, CioHaNjOi ; m.p. 212° When this compound is treated with sulphuric acid an intramolecular change takes place without elimination of anything. The re-arrangement concerns only the nitro- and acetylene-groups ; one oxygen goes to one of acetylene's carbons, breaking the triple bond, turning it into a single one, and taking possession of the two valencies thus set free ; the other oxygen sticks with one valency to the nitrogen and unites through the second valency with one of the other carbon's free valencies liberated by breaking the triple bond. There are now four free valencies left, three of which belong to the nitrogen and one to the second carbon. This last one unites with one of nitrogen's free valencies forming a closed chain (pentagon), and the two remaining free valencies of the nitrogen disappear, the pentad being reduced to a triad. Di-isatogen, CieHsNaO^ When, again, di-isatogen is treated with reducing agents, the oxygens inside the pentagons are withdrawn; two valencies thus set free unite the two isatogen-groaps by a doable bond, and the free nitrogen-valencies are each provided with a hydrogen from the reducing agent : Fia. 1099 Indigo, CieHipNaOa Indigo is obtained from several plants, but especially from Indigofera tinctoria, in which it is present in reduced state (indigo-white, fig. 1295, p. 365) as a glucoside. 310 NITEOGEN-COMPOUNDS In its quality of an acid, nitric acid forms compound ethers with alcohols. Some of these are Fia. 1100 Fia. 1101 o o J fi r~S Alcohol and nitric acid Ethyl nitrate, O2H5NO3 ; b.p. 86°-3 ; explosive fluid From glycerin and nitric add : Fia. 1102 Nitro-glycerin, glycerin nitrate, trinitrin, glonoin, angio-neurosine, CgHsNjOg ; an oUy fluid, explodes on heating ; poisonous ; used in neuralgia, migraine, asthma, cfeo. ; a mixture of nitro-glycerin and silioious earth (Silex farinaceus, Kieselguhr) is called dynamite As nitro-glycerin is a compound ether in which nitro-groups are joined to the carbon-atoms through an oxygen-atom by replacing hydrogen in hydroxyl, this name is scientifically not the proper designation. In nitro-compounds the nitro-groups are joined directly to the carbon-atoms, and not through the intervention of oxygen, because they displace the whole hydroxyl, and not its hydrogen only, as in the compound ether above. They are therefore identical with the corresponding nitro-hydrocarbons. The true nitro-glycerin is thus the same as tri-nitro-propane, and has the following structure : Fig. 1103 True nitro-glycerin or tri-nitro-propane, C3H5N3OS; oily fluid; b.p. 200°; the hydrogens other than the hydroxyls' in ajcohols cannot be replaced by nitro-groups From carbohydrates (p. 151), which it will be remembered are alcohol-aldehydes and alcohol- ketones, some important compound ethers are formed with nitric acid. The most noted amongst them are the cellulose compounds (vide p. 158). We do not know the structure of cellulose; the NITRIC ACID-COMPOUNDS 311 only thing we can conclude from its chemical behaviour is that it must be a combination of several molecules of hexoses by elimination of water, and that its empirical formula is (Cgil^QO^)x, where X stands for an unknown figure, which for the sake of illustration we will take to be equal to 2. We will further, for the same reason, suppose, quite arbitrarily — for we know nothing about it — that the two molecules are joined somewhat in lactide fashion (vide fig. 935, p. 257). Into this double molecule it is possible to introduce by way of etherification, from two to six, radicals of nitric acid. The hexa-nitrated ether would thus have some such structure : Pia. 1104 Cellulose hexa-nitrate, OiaHuNeOaa Other names are gun-cotton, pyroxylin, and, quite improperly (see above), nitro-cellulose. It is insoluble in a mixture of alcohol and ether. The chief constituent of the different sorts of so-called smokeless gunpowder is pyroxylin, prepared from various cellulose-sources (e.g. straw) mixed with other things, such as camphor, potas- sium-nitrate and -chlorate, barium-nitrate, &c., which either modify or increase its explosive property. The new smokeless powder, cordite, consists of gun-cotton dissolved in acetone and nitro-glycerin, being afterwards formed into strings or cubes. Celluloid is a mixture of pyroxylin and camphor. When nicrated cellulose is subjected to reducing agents the nitric radicals are removed and the pure cellulose is restored. Textile fabrics treated in this manner are said to become much stronger, and are disliked by moths and other insects. Such fabrics are known by the name of pilou. Compressed pyroxylin is used for torpedoes. Cellulose penta- and tetra-nitrate are soluble in a mixture of alcohol and ether, and used for the preparation of collodium ; hence they are distinguished as colloxylins. Mixed with nitro- glycerin they form a gelatinous mass used for blasting purposes. Ballistite is the name of one of these compounds. Zapon is the name of colloxylins dissolved in amyl-acetate and amyl-aloohol ; camphoide, if they are dissolved with camphor in absolute alcohol; and crystalline when dis- solved in methyl-alcohol. Future Nomenclature of Organic Compounds' Union with Combinations of Nitrogen and Oxygen The only two Congress rules referring to these compounds are — 1. Iso-nitroso-compounds will be considered cmd named oximes. Therefore they will be mentioned under that heading, p. 320. 2. Miro-compounds retain throughout their present designation. As the nomenclature of cyclo-compounds has not yet been settled, and as interpreters of the rules do not agree on the nomenclature of poly-valent radicals, it is impossible to give examples from the preceding pages except that of true nitro-glycerin (fig. 1103, p. 310), which will receive the name of 1 : 2 : 3 nitro-propane. 312 NITROGEN-COMPOUNDS NITROaEN AND HYDROGEN AniirLGiiia and Ammoniuni Nitrogen combines as a triad with hydrogen, forming ammonia : Fig. 1105 e—vi — o Ammonia, NH, ; a gag; b.p. —40° Like the behaviour of sulphur's valencies (p. 286), two more valencies in ammonia's nitrogen may come into play when an electro-negative group or element is affixed to one of them ; for instance, hydroxyl, chlorine, bromine, iodine, acid-radicals, &c. : Fig. 1106 Ammonium hydroxide, NH5O It is supposed to be existing in the solution of ammonia in water, but has not been isolated, nor has ammonium itself, which probably would consist of two ammonium radicals joined. Fig. 1107 Ammonium, N^Hg It is very much like a metal in its chemical properties, but should it ever be obtained in free state it would probably prove to be a gas. These two compounds can combiue in a most varied manner with other organic compounds, forming perhaps the largest and one of the most important sections of organic chemistry, including the alkaloids, the greater part of the modern synthetical remedies, and dyes. The study of this subject may be considered scarcely out of its ' teens ' yet, but is in a state of very promising development, growing so quickly that its most intimate friends would hardly recognise it after but a few years' absence. The process of combination takes place pa/rtly by the hydrogen-atom in the two compounds being replaced by other compounds, or even by one or more of their own kin, and pa/rtly by these two compounds, or their derivatives, replacing hydrogens in other compounds, although, of course, in some cases where two compounds only unite there is no distinction between the two processes. We may thus divide them into two large classes with subdivisions ; in the following classifica- tion, however, this is not adhered to, as thereby nearly allied compounds would sometimes be widely separated, and their relationship would be lost sight of A short description of the structural forms of the several classes will precede the derivatives of such members of each class as are supposed to have sufficient interest for us. PEIMAEY AMMONIA-BASES 313 Aramonia's OonilDinatioiis with Hydrocarbons Amines (Amido-compounds) MONAMINES Primary A m moaia-bases (amido-bases) If only one hydrogen-atom in ammonia is substituted by a radical we obtain what is termed an a mi do-compound ; if tbe radical is from the aliphatic series they are commonly distinguished as amines; in cyclo-compounds it depends upon how we regard them; if we look upon them as cyclo-compounds in which ammonia has been introduced we call them amido-compounds; but if we consider them ammonia in which cyclo-compounds have been introduced they also are termed amines. Pig. 1110 Fig. 1111 9 Fia. 1108 Fig. 1109 <►— O O ' • - o Methylamine, CHjN ; a gas Ethylamine, C2H7N ; b.p. 18°-7 G — <►— O Propylamine, C^HgN ; b.p. 44° Fig. 1112 Amido-benzene or phenylamine, aniline, CaH,N ; b.p. 184° Fig. 1113 O'—Cy—o o-Toluidine, C,HgN ; b.p. 197° Benzylamine, CjHsN ; b.p. 183° Methylamine occurs in a plant, Meraurialis annua and perennis, in herring brine, and in crude wood-spirit. Water absorbs more of this gas than of any other (1150 volumes at 12°-5). Ethylamine is a stronger base than ammonia. Propylamine is used in chorea and rheumatism ; is formed by the putrefaction of glue. Aniline, poisonous, has been used as a destroyer of lupus nodules. It is now manufactured on a large scale from nitro-benzene (vide p. 335), originating in the first instance from coal-tar. It is chiefly used in the colour industry. Bromamide, a new American anti-neuralgic, is said (Amer. Journ. Pharm.; Ph. G. xxxiv. p. 100) to be aniline, in which three benzene- and one amido-hydrogens are replaced by bromine. o-Toluidine occurs together with para- and meta-compounds in coal-tar. Fig. 1114 That part of ammonia which remains unaltered, NHj o»_^j)_-o is termed an amido-group. (For further development see p. 341.) 314 NITEOGEN-OOMPOUNDS Secondary Ammonia-bases (IMIDO-BASES) When two of the hydrogen-atoms in ammonia are replaced by hydrocarbon-radicals the com- pounds are termed secondary- or imido-bases, the rest of ammonia in which only one of the hydrogens is left undisturbed being designated as an imido-group, NH. Their nomenclature is formed by placing ' di- ' before the hydrocarbon radical, indicating that there are two of them in the compound. Thus we have Fig. his Fi8. 1116 Fig. 1117 G-A — ^^-..-^^-^ o— • — (» — d^ e i) o CI Di-methylamine, C2H7N ; b.p. 8° ; Di-ethylamine, C^HuN ; present in herring-brine and b.p. 57° sausages ; not poisonous Di-phenylamine, C12H11N ; m.p. 54° ; derivatives form dyes {aivrcmtia and di-phenyla,mine-blue) The substituting groups need not be of the same sort; they may be varied according to taste; for instance : Fig. 1118 Fig. 1119 -Q^ Methyl-aniUne, C,H,N ; b.p. 191° Ethyl-aniline, C3H11N ; b.p. 204° Fig, 1120 Pseudo-ephedrine, phenyl-hydroxy-propyl-methylamine, C10H15NO ; m.p. 114° (Heger, Neue Arzndmittel, 1891) ; a new mydriatic remedy, said to be ever so much better than any other. (For further development see p. 351.) SECONDARY AND TERTIARY AMMONIA-BASES 315 Tertiary Ammonia-bases (nitrilk-bases) When all three hydrogen-atoms in ammonia are replaced we obtain tertiary bases. The rest of ammonia consists, then, of an atom of the triad nitrogen, which may be considered the radical of tertiary bases, and is also distinguished as such by German chemists as nitrile, and its derivatives of this class as nitrile-bases, but it has not been generally adopted by English- speaking chemists, the name being reserved for another series of compounds, the cyanides of alcohol- radicals, where the three valencies are linked to one carbon-atom (vide p. 419). Analogous to secondary bases, the nomenclature is formed by placing ' tri- ' before the hydrocarbon-radical . Fio. 1121 Pig. 1122 9 -~0 + O ' *^ @— -O Ammonia + formic acid Ammonium formate, CH5NO2 ; m.p. 100° ; used in chronic paralysis Fia. 1153 Fia. 1154 J^ Ammonia acetic acid Ammonium acetate, C2H7NO2 ; m.p. 89° ; used in influenza complicated with bron- chitis, scarlatina, and yellow fever By substitution there is an alternative : the organic acid attaches itself either by its alkyl part or by its carboxyl part. In the former case we call the compounds amido-acids, in the latter case amides {acid annides or amine-acids). Y 2 824 NITEOGEN-OOM POUNDS AMIDO-AOIDS "From formio acid (fig. 666, p. 175) : Fig. 1155 o— C> - ^^ " Amido-formio acid, carbamio acid, CH3NO2, may also be looked upon as an amine-aoid, and will 1 mentioned as such afterwards 'Etotol acetic add (fig. 667, p. 175) : Fig. 1156 Amido-acetio acid, glyeoooU, glycocine, C2H5NO2 ; m.p. 232° ; decomposes Glycocoll (to be carefully distinguished from glycol, fig. 364, p. 76) is found in human urine; in the urine of herbivora it occurs in combination with benzoyl as hippuric acid (fig. 1185, p. 330). When mammalia are fed upon glycocoU it leaves the organism as urea, but from birds it is voided as uric acid. Amido-acids are rather peculiar compounds : their ammonia-end can combine with acids and their carboxyl-end with bases, at the same time they are in the free isolated state perfectly neutral. It has therefore been suggested (Ber. xvi. p. 2650) that the free compounds form a ring, perfectly analogous to betai'ne (fig. 1265, p. 355) by joining the carboxyl to the nitrogen, ammonia becoming pentad (ammonium). This strutjture, e.g., of glycocoll is thus represented : Fig. 1157 ^ In nearly all their derivatives, however, the closed chain is broken and is re-converted into an open chain ; they will here be represented in the usual form of the open chain, because thus they are better comparable ; besides, as structures with a closed chain, they would have to be referred to the derivatives from quarternary bases (i.e. betaines). If a methyl be introduced into the amido-group of glycocoll we obtain methyl-glycocoll : Fig. 1158 Sarcosine, methyl-glycocoll, CjHjNOa ; m.p. 210° AMIDO-AOIDS 325 From, propionic acid (fig. 669, p. 176) : Fio. 1159 Alanine, a-amido-propionio acid, CsH^NOa ; melts and sublimes at 255°, partially decomp. ; the meroury-salt is used in. syphilis. The iS-oompound is also known Cystine is formed from alanine by replacing the hydrogen joined to the central carbon-atom by the radical of sulphuretted hydrogen (SH). From caproic acid and iso-butyl-acetic add (figs. 673, 674, p. 177) : Fig. 1160 Fig. 1161 O — Q f-4 i i -#— o Q O Leucine, o-amido-caproio acid, CsHigNOa ; m.p. 170° ; occurs Leucine, o-amido-iso-caproic acid, O0H13NO2 ; ia abundantly in the animal organism as a product of kata- derived from vegetable proteids {Ber. xxiv. boUsm of proteids ; is the white substance in the ' eyes ' p. 669) of gruySre cheese From ethylene-lactic acid (fig. 693, p. 179) : Fig. 1162 ©-*o -^»o Serine, a-amido-ethylene-lactic acid, amido-glycerio acid, C3H7NO3 From succinic acid (fig. 714, p. 185) : Fig. 1163 Aspartic acid, amido-suecinic acid, C4H7NO4 ; may also be looked upon as malic acid, in which hydroxyl is replaced by an amido-group 326 NITROGEN-COMPOUNDS The aldehyde of this acid Fia. 1164 Aspartio aldehyde, C4H7NO2 ; hypothetical has, however, been suggested as the compound from which proteids are formed by condensation. From glutaria acid (fig. 719, p. 185) : Pig. 1165 -@— ^' Glutamio aeid, C5H9NO4 ; m.p. 202° ; is nearly always found together with aspartic acid From cfrotonic acid (fig. 740 p. 190) : Fia. 1166 yS-Amido-crotonio acid, O^HyNOa Amido-acids formed from the acrylic-acid series with a double bond are collectively dis- tinguished as leuceines, whereas those from the fundamental acid series are leucines. From eych-acids (p. 208) : Oyclo-acids, being aliphatic acids with a cyclo-hydrocarbon aflSxed to their alkyl part, can, there- fore, form similar compounds ; for instance, henzoic acid (fig. 812, p. 211). Fib. 1167 2)-Amido-benzoio acid, O7H7NO2 ; m.p. 186° According to the position of the amido-group there are also an ortho-acid (1 : 2), anthranilic acid, and a meta-acid (1 : 3), benzamic acid. AMIDES AND ACID AMIDES 327 Two or three amido-groups may be fixed to the benzene-ring, forming, theoretically, six di-amido-, and six tri-amido-benzoic acids, five of the former and two of the latter having been prepared. The amido-group need not always affix itself to the benzene-ring ; it can also enter the side- chain. An instance is pa/ra-coumwric acid (vide p. 216), where ammonia breaks the double bond, gives a hydrogen to one of the valencies, and the rest seizes the other. Fia. 1168 Tyrosine, i8-hydroxy-phenyl-alamne, ^-hydroxy-phenyl-a-amido-propionio acid, CgHnNOg ; m.p. 235° ; occurs in unhealthy liver, molasses, old cheese, pancreatic gland, and is a decomposition product from horn, albumen, feathers, hair, i^^ Diazo-benzeue-imide Sodium benzoate hydrazoio acid, N3H In order to keep my readers up to date, it may be mentioned that the formation of this acid entirely from inorganic bodies has quite recently been successfully performed (Ber. xxv. p. 2084J. Essentially the preparation is based upon this process : Fig. 1372 tt 9 Fig. 1373 ^q -<| Ammonia + nitrous oxide Hydrazoio acid and water The two gases, ammonia and nitrous oxide, do not act upon each other, but through the inter- vention of sodium reaction takes place, of which the above figures represent the extreme phases. Azoi'mide or hydrazoio acid is a light mobile liquid, b.p. 37°, and a strong acid, closely resemibUng hydrochloric acid. It is, however, very explosive and dangerous to handle. Judging from the structure of hydrazoic acid, one would think it possible to add two hydrogens to the molecule, breaking the double bond. Fio. 1374 This would be the molecule of imide, N3H3, which is now known only as the radical or group, NH. NITROGEN-OYOLO-OOMPOUNDS 385 NITROGBISr-OYCLO-OOMPOUNDS We have frequently had occasion on the preceding pages to make acquaintance with cyclo- compounds, in which carbon has been replaced by oxygen, sulphur, or nitrogen. I shall only call to mind, amongst pentagons, furfurane (fig. 941, p. 260), thiophene (fig. 1015, p. 285) pyrrol (fig. 1182, p. 329); and amongst hexagons, pyrone (fig. 945, p. 260), penthiophene (fig. 1017, p. 286), pyridine (fig. 1275, p. 359); and from the najphthalene configuration, quino- lirie (fig. 1304, p. 367). These are but a few examples in which only one carbon-atom is replaced; lihere are, however, many in which more than one carbon-atom has resigned its position to one or more of the elements mentioned, e.g., thialdine (fig. 1148, p. 322), in which three carbons are replaced, two by sulphur and one by nitrogen. But in point of variety of substitutions, none of the others can compare to the cyclo-compounds in which nitrogen alone is the substituting agent ; thus formed, the derivatives of each ring are so numerous that the rings are looked upon as mother substances, and special names have been given to each ; if that could have been done methodically and systematically all these names would have tended to facilitate the learning and understanding of chemistry, but their discoveries being unconnected, only spasmodic, and not mutually coherent, attempts have been made ; anyhow, we had better have a look at some of them, because there is always the risk of meeting one or other somewhere, although comparatively few are at present of direct interest to medical science. The mother rings will first be placed side by side, afterwards such derivatives of each as are likely to be of interest will be discussed ; with few exceptions the origin of them cannot now be gone into. For some it has already been given (e.g. pyrrol, pyridine, quinoline, &c.), for others it is not known, and for the rest they are either merely hypothetical or else wanting sufficient interest. c c 386 NITEOGBN-GYOLO-COMPOUNDS Azols with seven bonds, two double, three single bonds. Pentagons With one Nitrogen -atom A^zolines with six bonds, one double, four single bonds. Azolones if carbonyl present. Azolidines with five bonds, no double bond. Azolidones if car- bonyl present. Pia. 1375 Fia. 1376 Fie. 1377 . Pyrrol, C4H5N ; b.p. 131° ; formation vide fig. 1182, p. 329 Pyrroline, C4H7N; b.p. 91° Pyrrolidine, CiHgN ; b.p. -87° With two Nitrogen -atoms Fig. 1380 Fia. 1381 Pyrrolidone, O^HiNO ; m.p. 28° Fig. 1382 Pyrazol, C3H4N2 ; m.p. 70° {Ber. xxiii. p. 1105, xxiv. p. 171) Pyrazoline, C^HeNg ; a liquid ; properties not published {Ber. xxvi. p. 408) Fig. 1383 Iso-pyrazoline, CsHjNa (not isolated) Fig. 1384 Pyrazolidine, CaHaNj (pyrazine, not to be con- founded "with pyrazine, fig. 1402, p. 389) ; not isolated Fig. 1385 Pyrazolone, CsH^NaO; b.p. 152°-157<' {Ber. xxvi. p. 868) Iso-pyrazolone, CaH^N^O ; formation, fig. 1234, p. 344 Pyrazolidone, CgHoNaO {Ber. XXV. p. 1869) PENTAGONS 387 Fio. 1386 Fia. 1387 G — ® — O O-©— O Glyoxime + methane - two molecules of water Glyoxaline, C3H4N2 ; m.p. 88° Theoretically formed from glyoxime (fig. 1139, p. 320) and methane ; actually from glyoxal and ammonia (see also parabanic acid, creatinine, &c., p. 372, seg^.) With three Nitrogen-atoms Fio. 1388 Pio. 1388 a Triazole, C2H3N3; m.p. 120° Osotriazole, C2H3N3 ; m.p. 22°-5 ; formation (Ber. XXV. pp. 229, 744) ixam phenylosazonea, osotetrazones, &a. (Ann, oolxii. p. 261) With four Nitrogen-atoms Pig. 1389 Tetrazole, CHaNt; m.p. 165° ; formation from amidines {Ann. cclxiii. p. 81, cclxv. p. 129) With one Oxygen- and one JSTitrogen-atom A collective name proposed for these hypothetical compounds is azoxoles. Fio. 1392 Fia. 1390 FiQ. 1391 Oxazole, C3H3NO ; formation from acet-thiamide and chloraceUme Iso-oxazole, C3H3NO Oxazoline, C3H5NO c c2 388 NITEOGEN-CYOLO-COMPOUNDS With one Oxygen- and two Nitrogen -atoms (and a Oarbonyl) (Azoxazoles) Fio. 1393 Fio. 1394 Fia. 1395 Hypothetical furazane, CjHaNaO, and isomers ; formation from di-isonitroso-acids (Ber. xxiv. p. 1175, xxv. p. 2168 ; Ann. cclxiv. p. 178) PiQ. 1396 Biazolone, CaH^NjOj; toimation horn formyl-phenyl-hydraiine-derwatives aniphosgen [Ber. xxi. 2456) Hexagons "With one Nitrogen-atom (Azines) FiQ. 1397 Fio. 1398 Pyridine, G^U^N ; b.p. 116" Chemists disagree as to wMcli of these three formulse is the proper one. Possibly they are all three right, see p. 55, and formation, vide fig. 1275, p. 359. The first structure is in point of fact not a hexagon, but two interlocked tetragons, as already frequently mentioned (comp. also acridines, p. 340). HEXAGONS »89 With two Nitrogen-atoms (Diazines) When the two nitrogen-atoms are in ortho-position they are termed oiazines, in meta-position miazines, and in para- position piazines. FiQ. 1400 Oiazine, C^HiNsi ; hypothetical; only some few rather distant derivatives from this ring are known Fig. 1401 Pro. 1402 Pyrimidine (miazine), C4H4N2; Pyrazine (piazime), C4H4N2; m.p. 56°; hypothetical ; formation of oxy- derivatives from amldAnes and aceto-acetic ether b.p. 116° (JSer. xxvi. p. 723) ; the struc- ture is also represented with a diagonal bond between the two nitrogens ana- logous to pyridine ; formation from iao- ri/itroso ketones. Derivative : piperazine (fig. 1272, p. 358) "With tJiree Nitrogen-atoms (Triazines) «ym-Triazines, vide cyanuric acid and derivatives, p. 423. Witli four Nitrogen-atoms (Tetrazines) ¥ia. 1403 Fio. 1403 a <> Tetrazine, C^B^S^ ; hypothetical Oso-tetrazone, C2H4N4 ; formation trozn phev/ylosanone Heptagons, octagons, nonagons, and decagons with nitrogen-atoms are also known. 390 NITROGEN-CYOLO-COMPOUNDS Hexagons with one Oxygen- and one Mtrogen-atom (Azoxines or Oxazines) Fio. 1404 ' Fis. 1404 a Oxazine, C4H5NO ; hypothetical Morpholine, tetrahydro-oxazine, C4H9NO ; is said to have been isolated as a piperidine-like base Pentoxazoline, C^H^NG; formation from y-brompropylaimne (Ber. xxii. p. 2220, x»Ii. p. 249.3i xxiv. p. 3213 Fio. 1406 Interlocked. Rings "With one Nitrogen-atom 0^. Fia. 1407 w Quinoline, OgH^N ; formation, see fig. 1303, p. 367 Iso-quinoline, CgH^N ; m.p. 23° ; lyp. 240°'5 Fig. 1408 Cinnoline, CsHoN., ; hypothetical; formation of derivatives from dAazo ccmvpounds (Ber. xvi. p. 677) With two Nitrogen-atoms Fig. 1409 Quinazoline, CsHeN;; ; formation from ortlto-amido-bemamide and acid anhydrides {Journ. f. pr. Ch. xxxvi. p. 141) Fig. 1410 Juinoxaline, quinazine, CaHeNa ; m.p. 27°; b.p.229°; formation from aromatic ortho-dianvines and gVyoxal, oxalic aoid, &o. [Ber. xvii. p. 319) DERIVATIVES EEOM PENTAGONS AND HEXAGONS 391 Derivatives from IsTitrogen-cyclo-compounds Pentagons We have already had the opportunity of discassing most of those pentagon derivatives which have any claim on our attention, such as succinimide, p. 329, antipyrine, pp. 343, 344, weides, p. 372, seq. ; further, the many interlocked pentagons ; oxycwrbanil, p. 342, indole and skatole, p. 352, the derivatives of amido-acids, p. 363, and diureides, p. 375. Besides these, the only one whose derivatives possess interest from a medical point of view is glyoxaline (fig. 1387, p. 387), the methyl-ethyl-derivative of which is a base of alkaloid nature with a narcotic and strongly poisonous character. Fig. 1411 Ethyl-glyoxal-ethyline, OaHmNa ; b.p. 212° Ethyl-glyoxal-ethyline acts on the organism like atropine, and paralyses the vagus nerve; but if a hydrogen-atom is replaced by chlorine the new compound, chlor-oxal-ethyline, acts no longer like atropine, but like morphine upon the brain, yet still paralysing the vagus (Lauder Brunton, p. 84). Hexagons with one Nitrogen (Pyridine-compounds) Amongst the hexagons pyridine (fig. 1397 &c. p. 388) takes the first place in every respect; nearly all compounds which are now comprised under the designation alkaloids, and whose struc- tures have been ascertained, have something to do with pyridine. The derivatives of pyridine are analogous to those of benzene. Pyridine may be hydrated, i.e. the double bonds broken by the introduction of hydrogens inside the ring, or the hydrogens outside, may be replaced in the same way as we have seen those in benzene substituted. The isomers of pyridine-derivatives must, however, be much more numerous than those of benzene's, as the position of the substitutes in regard to nitrogen gives opportunity for many varieties. We shall first look at the substitution products of pyridine. Whereas all carbon-atoms in benzene were of equal value, and consequently only one methyl- 392 NITEOGEN-GYOLO-COMPOUNDS derivative, toluene (fig. 232, p. 44), was known, three derivatives from pyridine are not only possible but also known : Fia. 1412 o-Picoline(l:2), CeH,N; b.p. 133°-5 Pia. 1413 /i-Picoline (1 : 3), OeH^N ; b.p. 140°-142° Fig. 1414 7-Picoline (1 : 4 or^-), CeH,N ; b.p. 142°-144°-5 Similarly there are ethyl- and propyl-pyridines &c. ; Fia. 1415 Fio. 1416 o-Ethyl-pyridine, O7H9N ; b.p. 148°-5 ; three isomers a-Propyl-pyridine, oonyrine, CsHnNj b.p. 167°; three are possible and Icnown isomers possible and two known Two or three methyls may replace hydrogen-atoms ; Fio. 1417 o-o'-Di-methyl-pyridine, 0,Hs,N; b.p. 142" s-Tri-methyl-pyridine, OsHuN ; b.p. 171° But different alcohol-radicals also may replace hydrogen-atoms in the same molecule ; in this way there are numerous derivatives which have the same empirical formula though they are not identical; thus we have seen that ethyl-pyridine and di-methyl-pyridine have both the formula PYEIDINB-DERIVATIVES 393 C,H,N ; and a-propyl-pyridine and trimethyl- pyridine, OgH,iN. All those having the same empirical formula have received their collective names, e.g. Pyridine, O5H5N Picolines, OgF,N Lutidines, CjHgN Oollidines, Og HuN Parvolines, CgHjgN Corridines, OjoHigN Rubidines, 0,,H„N Viridines, C,2B[,gN Hexyllutidines, OigHjiN The theoretical isomers of the last member are almost innumerable, but happily the same law of limitation which we mentioned as existing for the hydrocarbons, p. 18, appears also to obtain here and everywhere. There are nine possible lutidines, of which we know seven ; twenty-two collidines are possible (including propyl-, isopropyl-, methyl-ethyl-, and trimethyl-pyridines), of which we know fourteen ; there should be hundreds of thousands of hexyllutidines theoretically possible, but all we know is one only. Alcohols and acids may be formed from pyridine analogous to benzene derivatives. Thus we know, of alcohols : Fia. 1419 Pioolyl-methyl-alkine, CsHnNO It has both basic and alcoholic properties ; such compounds are styled alkines, and their com- pound ethers (vide p. 231) alkeines {Ber. xiv. p. 1876 ; comp. p. 321). Of .mono-basic acids : Fio. 1420 Fig. 1421 Picolinio acid, 0- or a- or 1 : 2 pyridine-oarboxylio acid, CaHsNOa ; m.p. 135° Niootinio acid, m- or ;3- or 1 : 3 pyridine oarboxylio acid, OeHsNOs ; m.p. 228° The para- or 7-acid, iso-nicotinio acid, m.p. 305°, is also known. 394 NITROGEN-CYOLO-OOMPOUNDS And of di-basic acids : Fig. 1422 Fia. 1423 Qninolinie acid, o-m- or a^- or 1 : 2 : 3 pyridine-di- carboxylic acid, C7H5NO4 ; m.p. 231° Cinchomeronie acid, m-p- or Py- or 1 : 3 : 4 pyridine-di- carboxylio aoid, C^HsNOi ; m.p. 258° ; decomp. Six of them are theoretically possible and have been prepared. Another mono-basic acid is pyridine's combination with lactic acid (fig. 692, p. 179) : Fia. 1424 Fia. 1424 a -v;"" 9 or Pyridine-laotio acid, CoHsNOa ; a syrupy liquid From this acid pilocarpidine and pilocarpine may be formed, and vice versa. Pyridine- lactic acid has not as yet been prepared in any synthetical, but only derived in the analytical way from pilocarpine ; consequently the alkaloids cannot be said to have been fully prepared by synthesis. The formation of pilocarpidine is effected by di-methyl-amine (fig. 1115, p. 314) replacing the alcoholic hydroxyl ; two sets of figures are given below derived from the two structures of pyridine-lactic acid (above), the difference of which is merely in the arrangement of the four links round the central carbon-atom ; the first figure in each row is derived from fig. 1424, the others are constructed upon 1424 a in order to show their striking analogy to betai'ne, its derivation and deriva- tives as set out on p. 356. Pig. 1425 a Fia. 1425 b Tig. 1425 #— O Pilocarpidine, C10H14N2O2 ; deliquescent PYEIDINB-DERIVATIVES 395 Pilocarpi dine is one of the three alkaloids contained in the leaflets ot Pilocwrpus pennatifoUus (Jahorandi, B.P.), the others being two antagonistic compounds, pilocarpine and jaborine, which sometimes are present in such proportions as to balance each other and i-ender jaborandi inert ; an analogous case is that of the poisons in Agaricus musewrius (vide p. 355). A fourth alkaloid, jaborandine, closely allied to the others, does riot occur in jaborandi, but in the leaves of Piper reticulojtum. By transforming the di-niethyl-amine group into tri-methyl-ammonium-hydroxide (comp. fig. 1124, p. 316) we obtain Fia. 1426 Fig. 1426 a Pilooarpio acid, C11H13N2O3 The proximity of the alcoholic and carboxylic hydroxyls (proper regard being had to the stereo- metrical form of fig. 1426a) makes it possible to withdraw a molecule of water, and the two free valencies will join : Fig. 1427 Fig. 1427 a -6 Pig. 1427 b ■OOr-^\—0 a Pilocarpine, CnHigNaOa ; amorphous The structures of jaborine and jaborandine have not yet been fully ascertained. Hydrated Pyridines Four or sir hydrogen-atoms may be introduced into the pyridine-ring, breaking a corresponding number of double bonds'. By the introduction of six atoms, piperidine (fig. 1274, p. 359) is formed ; we have before (I.e.) derived it from penta-methylene-diamine. 396 NITROGEN-CYOLO-COMPOUNDS The structure of piperidine was this: Piperidine, C5H11N We can by substitution affix side-chains to this ring, such as alcohol- and acid-radicals, or replace the hydrogen-atom in the imido-group by nitrosyl (fig. 1067, p. 301) &c. Piperidine - derivatives If propyl replaces the hydrogen in a-position, we obtain the alkaloid conine : Fio. 1429 Conine, a-normal-propyl-piperidine, CeH^^^N ; b.p. 167° ; the poisonous principle of Comum maculatwm (hemlock) If a hydroxyl is introduced into the side-chain another alkaloid, conhydrine, is formed : Pig. 1430 Conhydrine, conydrine, a-piperidyl-ethyl-altine, CsHitNO ; m.p. 121°. (Mark the similarity in the name conyrine, fig. 1416, p. 392) The position of the hydroxyl is not conclusively ascertained ; it may be on the carbon-atom at the end of the side-chain, in which case conhydrine would be lupetidylalkine (comp. p. 397). As regards the distinction of this alkaloid as an alkine, vide footnote, p. 321.- It is found together with conine in hemlock. HYDRATBD PYRIDINE-DBRIVATIVES Amongst the acids with which piperidine majr combine ia piperic acid (fig. 833, p. 221): Fia. 1431 397 Ti jir Arecajidine, CyHi^KOs ; is therapeutically inactive Arecoline, CsHiaNOj ; oily liquid ; is the only anthelmintic principle in the areca-nut ; poisonous like pilocarpine and partly like pelletierine (CaHuNO), an alkaloid of un- known structure from Punica granatum The two alkaloids found in the areca-nut are inert, and contain two carbonyl-groups ; their relation to the others will easily be understood from the illustrations : Fio. 1448 Fia. 1449 Guavacine, CeHsNO^ ArecEiine, C7H11NO2 D D 2 404 NITROGBN-GYOLO-COMPOUNDS Quinolme - derivatives When a pyridine-ring is interlocked with a benzene-ring we call the compound quinoline. We have already mentioned its formation from o-amido-cinnamic aldehyde (fig. 1303, p. 367); another formation is from aniline (fig. 1111, p. 313), and acrolein (fig. 548, p. 133) : Fig. 1450 -®-i i 9 Aniline m acrolein Via. 1451 G— #— ^ Quinoline, Cja.^'S. ; b.p. 236" Acrolein may be prepared from glycerin (p. 133) ; therefore quinoline is by this reaction prepared from aniline and glycerin, being heated together with sulphuric acid, which takes away the water, and nitrobenzene, which provides the necessary oxygen to form the water, as shown above. This synthesis caused some sensation at the time, and has been named, after its discoverer, Shraup's synthesis. In coal-tar, where quinoline is found ready formed, another compound also occurs that differs from quinoline in the position of the nitrogen which has been found placed in a-position : Fia. 1452 lao-quinoline, CgH^N ; m.p. 22° ; b.p. 240" It has also been synthetically prepared, and is important as mother substance of several alkaloids. If in the formation of quinoline, we take alhylated acroleins, i.e. the higher homologues, instead of acrolein we obtain alkyl substituted quinoUnes, with the substitute in the pyridine-ring (N.B. : the QUINOLINE-DERIVATIVES 405 homologues join with their ends reversed and the bonds re-arranged) ; e.g. croton-aldehyde (fig. 549, p. 133) forms a-methyl quinoline : Fio. 1453 Quinaldine, o-methyl-quinoline, C10H9N ; b.p. 138° It is also designated as j«/-a-niethyl quinoline, py- indicating substitution in pyridine-ring. If aniline is alkylated, e.g. o-toluidine (fig. 1112, p. 313), we obtain a quinoline with substitu- tion in the benzene-ring, toluquinoline: Fia. 1464 o-ToluquinoUne, 62-1-metliyl-quinoline, OioHgN ; b.p. 248° bz- indicates that the substitution has taken place in the benzene-ring ; the numeral signifies the position. This designation by hz- and py- seems rather superfluous when the position in the benzene-ring is indicated by numerals, and in the pyridine-ring by Greek letters. A great number of isomers of these alkylated quinolines are both possible and known. When hydroxyl replaces a hydrogen-atom in quinoline it is termed anoxyquinoline (hydroxy- quinoline), if the substitution takes place in the benzene-ring; but a carbostyril if the hydroxyl is placed in the pyridine-ring. Fig. 1455 Fio. 1456 Quinoplienol, o-6s-l-oxyquinoline, CgH^NO ; m.p. 75° ; Carbostyril, py-2- (or a-) oxyquinoline, CgHjNO ; m.p. 200° Six out of seven possible isomers have been prepared The formation of carbostyril and its tautomeric form, pseudo-carbostyril, from amido-cinnamic acid has already been discussed, p. 366. 406 NITROGEN-OYOLO-OOMPOUNDS Through their hydroxyls these oxy-quinolines may form ethers, e.g. Fio. 1457 Quiuolidine, quinanisol, p-methoxy-qninoline, Ci„HgNO ; b.p. 304° (740 mm.) It may be synthetically prepared according to Skraup's method from -p-amido-anisol (anisol, vide fig. 494, p. 116) and acrolein (comp. p. 404). Garboxyls may also be fixed upon quinoline and the derivatives mentioned, in different positions converting them into acids. Thus we have from quinoline itself Pio. 1458 Fio. 1459 Quinaldinio acid, a-quinoline-carboxylic acid, Ci„H7N02 m.p. 156° Cinchoninic acid, 7-qumoline-carboxylic acid Ci„H,NOa ; m.p. 253° and from quinolidine Fio. 1460 Quininic acid, OnHaNOa ; m.p. 280° ; not to be confounded with quinic acid (fig. 809, p. 210)— quite a di^erent compound QUINOLINE-DERIVATIVES Of a more complex structure are the following ' new remedies ' : Pig. 1461 Fio. 1462 407 Aoetamide , (fig. 1172, p. 328) Quinoline- Bthoxyl (fig. 389, p. 81) ^Benzoyl-amide Quinoline -Bthoxyl Analgeue, ortho-oxethyl (ethoxyl)-a»M-monacetyl-(or benzoyl)-amido-quinoline, C13H14N2O2 ; m.p. 155° {Ph. C. xxxii. p. 433) ; antipyretic and antirheumatic. Observe the analogy to phenacetine, saliphene, &o., pp. 348 sec[. Analgene was originally started as an acetyl compound (the first figure), but lias recently appeared as a benzoyl-compound (the second figure) (Benz-analgene, Ph. 0. xxxiii. p. 727). PiQ. 1463 Ciaphterine, oxyquin-aseptol, ortho-phenol-oxy-quinoline-sulphonate, CisHiaSNOs ; non-poisonoua, antiseptio 408 NITROGEN-CYCLO-COMPOUNDS Diaphterine is a combination of hydroxy-quinoline (fig. 1456, p. 405) and aseptol (fig. 1045, p. 292), nitrogen appearing in the character of a pentad (Ph. 0. xxxiii. p. 320 ; Ph. Ztg. 1892, p. 317). Later researches have established the presence of two molecules of hydroxy-quinoline in the compound, the second substituting the hydrogen in aseptol's hydroxyl, exactly in the same manner as the first has substituted hydrogen in the sulphonic acid ; accordingly its chemical formula would be 0,,H,„SN„O, Iodine and chlorine are said (Heger's Synopsis) to enter into the quinoline-structure as additions to the nitrogen by its changing from a triad into a pentad : Fia. 1464 Quinoiodine, C9H7NICI ; antiseptic and antithermic ; used in phthisis and angina pectoris It is, perhaps, more probable that the halogens substitute the hydrogens in a- and ;3-positions, analogous to di-chloro- quinoline (Beilst, iii. p. 746) ; the empirical formula would then be C9H5NICI. Hydrated Quinolines Like all closed chains built on the benzene pattern, hydrogens may be added to the rings of quinoline by breaking the double bonds. Thus di-, tetra-, hexa-, and deka-hydro-quinolines have been formed, the pyridine-ring being by preference first filled, and only when that cannot accept any more (four) hydrogen-atoms, the benzene-ring is entered. Of these, tetra-hydro-quinoline is important on account of its relation to some well-known alkaloids : Fio. 1465 Q Tetra-hydro-quinoline, CsHuN ; b.p. 244° It is an interesting compound in so far as it formed the starting-point for the preparation of several alkaloid-like substitutes for quinine. These derivatives have mostly been superseded by other and better compounds, but as they have historical interest they are worth mentioning. Thus by introducing a methoxyl in the para-position thalline was obtained : Fio. 1466 Thalline, para-methoxy-tetrahydro-.quinoline, CioHigNO ; m.p. 42° ; is stiU used for fevers in children, and in typhoid as a sulphate, tartrate, or hydroohlorate QUINOLINB-DERIVATIVES With a methyl fixed to the nitivgen kairoline is obtained Fro. 1467 409 Kairoline, methyl-tetrahydro-quinoline, CjoHigN ; b.p. 242" A hydroxyl may be introduced in ortho-position, producing Fro. 1468 o-Hydroxy-methyl-tetrahydro-quinoline, CioHigNO ; m.p. 114° ; febrifuge The chloride is termed kai'rine, or ka'irine M. If ethyl is joined to nitrogen instead of methyl it is distinguished as kai'rine A. When a ca/rboxyl replaces the meta-hydrogen in methyl-lcamne, we get another new antipyretic ; Hydroxy-methyl-tetrahydro-quinoline-oarboxylio acid, CnHiaNOs ; antipyretio The sodium salt has been awarded the trade name thermifugine. 410 NITROGEN-CTCLO-COMPOUNDS We now come to the alkaloids contained in the barks of the various species of cinchona, and derivable from a combination of tetra-hydro-quinoline with qiiinoline, as far as their structures have as yet been ascertained. The cinchona bark contains a great variety of things : six acids (amongst them quinic acid and oxalic acid have been determined), three neutral substances, and twenty-four bases at least. The structures of two of the bases, viz. cinchonine and quinine, have probably, up to a certain point, been ascertained. Cinchonine, the empirical formula of which is OigHg^NjO, can, by removal of a molecule of water, be converted into a compound termed cinchene, 0, H N From this compound a molecule of ammonia, NHg, can be split off, but at the same time a molecule of water re-enters the com- pound, which then is termed apocinchene, OijH,gNO. The structure of apocinchene has been ascertained in its main features (Ber. xxvi. p. 713); it consists of a combination of quinoline and a (U-ethylated phenol, in which the positions of hydroxyl and the two ethyls have not yet been ascer- tained with exactitude ; so much is, however, known, that their relative positions are either 1:2:3 or 1 : 3 : 4. Provided, therefore, that we have apocinchene we should be able to prepare cinchonine by reversing the above processes, viz. first by introducing ammonia and splitting off water, forming cinchene, and secondly by introducing again water, forming cinchonine. We can illustrate these processes in the following way, giving to hydroxyl and the two ethyls in apocinchene the relative positions 1:3:4, merely because the different groups come out better thus in the illustrations : Fig. 1470 Fia. 1470 a Fig. 1470 b Fig. 1471 Apocinchene, CigHigNO ; m.p. 209°-210° Apocinchene + ammonia —water = Cinchene, CigHjoNa ; m.p. 123°-125° Cinchonine, CigHagNjO ; m.p. 268°'8 (cinchene + water) Cinchonine would, according to this structure, be quinoline combined with a hydroxylated, methylated, and hydra ted iso-quinoline. Cinchonine is known for certain to be a di-tertiary base with a hydroxyl outside a quinoline group ; still the above representation is not quite the correct structure of cinchonine, because it has been ascertained (Monatsh. xii. and xiii.) that two molecules of hydroiodic acid can be added to the structure besides one that converts the compound into the hydroiodic salt. None of these enter into the quinoline group, though the evidence, upon which this assertion rests, does not seem quite conclusive, and in the iso-quinoline group, as represented above, there is room for only two molecules of hydroiodic acid', one breaking the double bond and the other forming the salt by turning the nitrogen into a pentad. The illustrations are therefore only intended to give an idea of our present knowledge of the subject. Cupreine. In the bark of Cinchona cuprea or of Bemijia pedunculata an alkaloid is present, which has been called cupreine: it is nearly related to cinchonine, the difference between them being a hydroxyl, which is affixed to the quinoline-ring in cupreine. Quinine differs from cupreine by the presence of a methyl-group joined to the aforesaid quino- line-hydi'oxyl. For the sake of illustration we will suppose the above structure of cinchonine (fig. 1471) to be correct ; cupreine's and quinine's structures may then be illustrated thus : QUINOLINE-DERIVATIVES 411 ¥ia. 1472 A ¥m. 1472 b Cupreine, CigHajNaOa ; m.p. 198° * Quinine, C20H24N2O2 ; m.p. 177° As will be seen, quinine is the methyl-ether of cupreine. The synthesis of quinine and the allied alkaloids has not yet succeeded ; the synthetical prepara- tion of apocinchene through phenyl-quinoline is being investigated, and will probably be carried out before long, and quinine has already been prepared from cupreine by substituting methyl for hydrogen in the hydroxyl of the quinoline group (Gompt. Bend. cxii. p. 774) ; but how apocinchene is to be converted into cupreine or cinchene is not yet discovered. Quinidine and cinchonidine are isomers (possibly stereometrical) of quinine and cinchonine respectively. Homoquinine, also a base found in the bark of Cinchona cuprea, is a combination of one molecule of quinine and one molecule of cupreine. Antiseptol is the sulphate of one of the above-mentioned iodine-com/pounds of cinchonine. It is employed in lieu of iodoform. We are next coming to a couple of alkaloids of special interest, because we have succeeded in pulling them to pieces, and by so doing have been enabled to see how the building should be put together, though we have not profited so much by it that we can perform the same work as our Grand Master. The two are : narcotine, one of the opium-alkaloids, and hydrastine, found in the root of Hyd/rastis ccmadensis. They have a further interest to us in the analogy of their formation. Though we do not know actually how to build them up from the foundation-stone, methane, it is easy enough to do so on paper ; and because, as a rule, it is more pleasant to build up than to pull down, we will do so here, and commence with narcotine. From methane is derived, through several intermediary stages which have already, but discon- nectedly, been described (more fully illustrated under the next alkaloid, p. 414), an acid which we know by the name of gallic acid (fig. 834, p. 221) : Fm. 1473 Gallic acid, CjHsOj 412 NITROGEN-CYCLO-OOMPOUNDS We combine by etherification two methyls with this acid : Fig. 1474 Di-methyl-gallio acid, CgHmOs By oxidation we can split off two hydrogen-atoms, one from hydroxyl and the neighbouring methyl respectively, and at the same time introduce another carboxyl : Fig. 1475 Gotarnic acid, CioHgO, For similar formation see safrol, fig. 504, p. 120. The first carboxyl may then be split off: Fig. 1476 Methyl-methylene-gallio (pyro-gallol-oarbonio) acid, CgHgOs ; m.p. 210° QUINOLINB-DEEIVATIVBS 413 This acid may be reduced to aldehyde and simultaneously combined with methyl-ethyl-amine. Fio. 1477 Cotarnine, O12H15NO4 ; m.p. 132° If cotarnine is brought together with opianic acid (fig. 922, p. 253) they join, through their aldehydes which are present in the structure of both, but not before these aldehydes have each formed an interlocked ring with its nearest side-chain, cotarnine forming an iso-quinoline ring (fig. 1452, p. 404), and opianic acid, meconine (fig. 924, p. 254). PiQ. 1478 PiQ. 1479 Narcotine, CuaHjaNOT ; m.p. 176° 414 NITEOGEN-CYCLO-COMPOUNDS Hydrastine has been investigated in the same way, and very interesting analogies have turned up. They have been arrived at by pulling down, as was the case with narcotine, but we will again choose the reverse method, and commence with the very source of all organic bodies, methane, as it may perhaps prove interesting to see the gradual growth from this our simplest hydrocarbon to one of the more complex compounds, just as we have with narcotine, but not so fully. It will now be sufficient to give the figures and refer to their respective places in this treatise. Fio. 1480 — O t> Methane (fig. 14, p. 7) Fig. 1481 -O Ethane (fig. 41, p. 12) Fia. 1482 ©- LL. Fio. 1483 Ethylene (fig. 179, p. 35) Acetylene (fig. 206, p. 39) Fia, 1484 Fig. 1485 FiQ. 1486 Fig. 1487 Benzene (fig. 157, p. 32) Pyrocateohin (fig. 418, p. 92) Homo-pyrooateehin (fig. 431, p. 96) Protocatechuic alcohol (fig. 463, p. 106) Fig. 1489 9 Yy. Protocatechuic aldehyde (fig. 561, p. 136) Vanillin (fig. 562, p. 186) Piperonal (fig. 564, p. 137) QUINOLINE-DERIVATIVES 415 Compare now piperonal with methyl-methylene-gallic acid (fig. 1476, p. 412), because the analogies between narcobine and hydrastine are becoming more striking. Eor comparison's sake we lay piperonal a little over on the side : Fia. 1491 Fia. 1492 and combine it with methyl-ethylamine : Piperonal Hydrastinine, CnHiaNOa ; m.p. 116° When hydrastinine is brought together with opianic add, hydrastine is formed by a process entirely analogous to the formation of narcotine from cotarnine and opianic acid : 'Si o a 'a m ( tn FiQ. 1493 FiQ. 1494 Hydrastine, CjiHuiNOa ; m.p. 135° (Ann. colxxi. p. 311) As pointed out before, this building up of hydrastine is merely theoretical ; the reverse way, commencing with hydrastine and finishing with methane, is, however, actual. An alcoholic exbraot of the root of Hydrastis canadensis, prepared in America, is also called hydrastine. 416 NITROGBN-CYGLO-COMPOUNDS Another alkaloid presenting several points of analogy to tlie two preceding ones is berberine, found together with two more alkaloids (oxyacanthine and berbwmine) in the root of Berber is vulgcms. I shall only give the structure of it {Jo-urn. Gh. 8oc. 1889, p, 63; 1890, p. 992), and leave to the reader to find out for himself the similarities, and to build it up from methane ; it is as good as any average Christmas puzzle : Tia. 1495 13erberine, CaoH^NO^ ; m.p. 120° Attention is invited to the anthracene-like connection between the two chief-groups. Besides those already discussed (meconine and narcotine) there are some twenty other consti- tuents of opium. Of these there are three acids — meconinic acid (fig. 923, p. 254), lactic acid (fig. 692, p. 179), and sulphuric acid — the rest are bases. Some of the latter are more or less related to narcotine, most of them are found in such small quantities that the researches on their structure have been considered less important. The most important of all, morphine, has, however, been the subject of much investigation, but its nature does not seem to have been entirely disclosed. It used to be considered a pyridine-derivative, but more recent investigations point to a phenantrene- (fig. 151, p. 31) compound, of which the following structure has been suggested (JBer. xxii. p. ] 113) : Fig. 1496 Morphine, Cj^HigNOa Here we have phenantrene all right enough ; but in order to place the rest a new ring has to be employed containing the oxygen- and nitrogen-atoms. This ring is the morpholine-ring, MORPHOLINE-DERIVATIVES 417 mentioned before (fig. 1404 A, p. 390). Other investigators (Monatsh. x. pp. 101, 732) have objected to the whole structure because in it one methyl only is affixed to the nitrogen, whereas they have found ethyl-methyl-amine amongst the decomposition products from morphine. The matter will be cleared up some day, no doubt, but it does not seem impossible that ethyl-methyl-amine may be split off from such a peculiarly formed structure as the above, where it seems anticipated and almost ready to be formed. Apomorphine is morphine less a molecule of water. Supposing the above structure correct, the water would most likely be formed from the hydroxyl and hydrogen which have broken the double bond of the morpholine-ring, and apomorphine would then have such structure : Fia. 1497 Apomorphine, Ci^Hi^NOj Apomorphine is said to be the 'active principle' in the American Gold Cure for habitual drunkenness. ' Codeine differs from morphine by a methyl joined to the hydroxyl in phenantrene. Fig. 1498 Codeine, CjaHaiNOa ; m.p. 150" Codeine has been prepared by methylating morphine. Apocodeine is formed from codeine by elimination of a molecule of water, probably in the same manner as we have just supposed apomorphine to be formed from morphine. E E 418 NITROGBN-OTOLO-COMPOUNDS As regards quantity, the third most important alkaloid in opium is papaverine. ^The structure of' this compound has been fully accounted for, and may be represented thus (Monatsh. ix. p. 781) : Fia. 1499 Papaverine, C, This is about all that we know of the structures of alkaloids. There is one more compound to mention before we close this chapter, viz. orexine ; it is one of the ' modem remedies,' a derivative from quinazoline (fig. 1409, p. 390) by hydrating and ioining it to a phenyl : "' Fig. 1500 Orexine,plienyl-dihydro-quinazolme, CiiHiijNj; m.p. 130°; the hydro-chlorate (m.p. 231°) is used as a stomaohicum ; recently the hase itself has been recommended in preference (Thera^. Monatsh. 1893 ; Ph. 0. xxxiv. p. 393) OYANO-DEEIVATIVES 419 CTANOaEIT AND DEEIVATIVBS We have seen nitrogen and carbon united by one or two valencies, but they may also be bound together by three valencies, forming cyanogen, or even by four, forming iso-cyanogen. Fig. 1501 Fia. 1502 ^ Cyanogen-group Iso-oyanogen-group Both, it will be seen, are mono-valent groups, but in cyanogen- the free valency belongs to the carbon-atom, in iso-cyanogen to the nitrogen-atom. There are derivatives from both ; with few exceptions they have not found their way into materia medica, but we cannot pass them entirely unnoticed, as they are of great importance to chemistry generally. The cyanogen-group is in all ordinary cases formed by preference, but in the presence of silver the iso-group is formed. This is on all fours with the behaviour of silver towards nitrous acid (vide p. 302). Cyanogen itself is composed of two cyanogen-groups. Fia. 1503 Cyanogen, CjNa ; a gas It is strikingly like an element, and has many analogies to chlorine ; for which reason it ia frequently given the chemical symbol Oy. When a hydrogen is affixed to the cyanogen group, hydrocyanic acid is formed : Fig. 1504 Hydrocyanic acid, HON or HCy ; b.p. 26°'5 ; occurs in amygdalin, bitter almonds, clierry and laurel leaves ; a deadly poison ; by substituting metals for the hydrogen, salts are formed, just like hydrochloric acid The hydro-iso-cyanic acid is not known, neither are any of its salts. Hydrocyanic acid forms with iron rather peculiar compounds, which combine with potassium- cyanide and form potassium-ferro-cyanide and potassium-ferri-cyanide. Their structures consist of two atoms of iron bound together by double bond in the ferro-compound, by single bond in ferri- compounds ; to each iron-atom two rings are affixed, each consisting of three cyanogens, thereby leaving altogether eight valencies free in the ferro-, and six in the ferri-compound, to which either E a 2 420 NITROGEN-COMPOUNDS hydrogen, making acids, or metals, making salts, may be joined. This is easily understood from a representation of their structures : Fig. 1505 Fig. 1506 Hydro-ferro-oyanio acid, CisHgNiaFej ; white crystals rapidly becoming blue on exposure Hydro-ferri-cyaniG acid, CijHuNijFej ; brown crystals ; easily decomposed AVTien potassium replaces all the hydrogen-atoms in hydro-ferro-cyanic acid it changes into the salt, potassium-ferro-cyanide, known as yellow prussiate. When the hydrogen-atoms in hydro-ferri-cyanic acid are replaced in the same way, the result is potassium-ferri-cyanide or red prussiate The molecular weight of these compounds is not known, but in the above figures iron is supposed to be tetra-valent, and, therefore, these structures are probably correct representations of the two compounds. Generally, however, they are for brevity's sake represented by half of these molecules (e.g. OgH^NgFe and CgHjNgFe), whereby iron becomes either a dyad or a triad. From the two potassium salts, prussian-blue and Turnbull's blue are derived. Both cyanogen and iso-cyanogen form derivatives with alcoholHradicals (by substituting the hydroxy! of an alcohol). The former are distinguished as nitriles (comp. p. 315) or alkyl- cyanides, the latter as carbamines (carbyl-cmhines) or iso-nitriles (iso-eywnides). Thus we have Fig. 1507 9 < r:~B ■■ Fig. 1508 O—iV Methyl-cyanide, aceto-nitrile, C2H3N ; b.p. 82° ; possesses an aromatic ethereal smell Methyl-iso-cyanide, methyl-carbamine, methyl-oarbylamine, C2H3N ; b.p. 58° ; unbearable odour As methyl-cyanide is the nitrile of acetic acid, hydro-cyanic acid may be considered the nitrile of formic acid. OTANO-DBRIVATIVES Cyanogen combines also with alcohols by substitution of a hydrogen of the latter. 421 Fio. 1S09 Cyanhydrine, C3H5NO ; b.p. 182° may also be considered the nitrile of ethylidene-lactic acid (fig. 692, p. 179), or of propylene-glycol (fig. 366, p. 77). When the three methyl-hydrogens are replaced by chlorine, or if cyanogen combines with chloralhydrate (fig. 977, p. 272) by replacing one of the hydroxyls, we obtain Fio. 1510 Chloral-cyan-hydrine, oMoral-oyanhydrate, C3H2CI3NO ; m.p. 61° ; recommended as substitute for aqua amygd. amar. If one of the hydrogen-atoms of methyl-cyanide is displaced by a nitto-group (vide p. 304), we obtain an acid that forms extremely explosive compounds : Fig. 1511 Fulminic acid, CoflaNnO, '2J-*-2-^^2^2 Tulminic acid itself has not been prepared, but compounds in which both hydrogen-atoms are replaced by metals are known. One of them is fulminate of mercury, used in percussion caps. Several structures, chiefly as iso-nitroso compounds (di-oximes, vide Ber. xxiii. pp. 2998, 3505, &c.), have been suggested, but the opinion is at present generally in favour of the above. 422 NITROGEN-COMPOUNDS Hydroxyl may apparently combine in three dififerent ways witt cyanogen and iso-cyanogen ; either it may join the carbon atom in cyanogen, Fig. 1512 No. 1 CHNO or its oxygen may join the carbon, and its hydrogen unite with the nitrogen ; two of carbon's valencies engaging the oxygen, the other two remaining with the nitrogen, whose third valency has been set free from its engagement to carbon, and therefore can accept hydroxyl's hydrogen : Fig. 1513 No. 2 CHNO A third way for hydroxyl is, of course, to join the nitrogen in iso-cyanogen : Fig. 1514 No. 3 CHNO The first two must be acids, the third is a sort of hydroxyl-amine which is awaiting discovery. We, however, know but one acid, cyanic acid, and opinions are very much divided as regards structure, whether it is cut on the first or on the second pattern. It will be noticed that the whole difference is the position of the hydrogen-atom, in one it is to the right, in the other to the left, the bonds being obliged to accommodate themselves accordingly. Now, as there undoubtedly are two series of derivatives from cyanic acid, and the.atoms in cyanogen compounds appear to possess great migrating aptitude, it is possible that cyanic acid has alternately both forms in quick succession, and that it depends upon the nature of the body it comes into contact with, in which position the hydrogen will finally settle down. Cyanic acid, whatever its structure may be, is a very unstable body : it exists only at temper- atures under zero ; at ordinary temperature it polymerises with explosion-like violence into a com- pound termed cyamelide (OHNO);^. Amongst its salts, one has historical interest, as it was the first brick pulled down from the wall that up to that time (1828) separated organic from inorgcmio chemistry. It was the transforma- tion of ammonium-cyanate into urea, effected by Wohler. This reaction will best be understood when we choose structure No. 2 for cyanic acid. Fig. 1515 Fig. 1516 Ammonium cyanate Urea (fig. 1174, p. 328) CYANO-DERIVATIVBS 42S The two nitrogen-atoms divide the hydrogen-atoms between them, whereby one of carbon's valencies is set free, and is seized by the rest of the ammonium-group. This intramolecular- change is effected simply by heat, and also at ordinary temperatures, but slowly. Ammonium cyanate may be formed from entirely inorganic bodies, whereas urea is an organic, compound, which, like all other organic compounds, was, prior to Wohler's discovery, believed to be exclusively the product of a special ' vital force.' Cyanic acid and alcohol radicals may combine. In these derivatives cyanic acid shows its capability of assuming two structures, some of the compounds being derived from structure No. 1, others from No. 2. The former are true compound-ethers ; the latter are not, as will be seen from their structure : Fig. 1517 Fig. 1518 -00 OyanethoUne, CsHsNO ; an oily fluid ; decomp. on heating Ethyl-iso-oyanate, ethyl-oarbonylamine, O3H5NO ; b.p. 60° ; of suffocating odour A polymerisation of three atoms of cyanic acid is known and termed cyanuric acid, of which there are two series of derivatives, cyanuric and iso-cyanuria compounds. The former seems to be derived from No. 1 of the cyanic acid structures, the latter from No. 2 : Fig. 1519 Fig. 1520 Cyanuric acid, C3H3N3O3 Iso-oyanurio acid, C3H3N3O1 We have met with similar isomers before (comp. phloroglucin, fig. 424, p. 93). Cyanuric acid only is known in the isolated state, but alcohol-radical-derivatives have been prepared from both. The alkyls fix themselves to the hydroxyls in cyanuric acid, and to the imido-group in iso-cyanuric acid, in both cases, of course, replacing the hydrogen-atom. Amido-groups may replace, one by one, the hydroxyls in cyanuric acid, forming ammelide, ammeline, and melamine, according as one, two, or three hydroxyls are replaced: Fig. 1521 Melamine, C3HaNe ; crystals ; decomp. on heating 424 NITROGEN-COMPOUNDS Derivatives of an isomeric melamine exist, which may be considered derivable from iso-cyanuric acid : Fig. 1522 Iso-melamine, CaHgNo Iso-melamine is only known through its alkyl-derivatives. The oxygen in the two structures of cyanic acid may be substituted by sulphur, as we have seen it done, in the previously mentioned thio-compounds (p. 280). We obtain then thio-acids of the following structures : Fm. 1523 Fig. 1524 No. 1 No. 2 Thio-cyanic acid, CHNS ; it is only stable in a freezing mixture The salts of the first structure are known as rhodanides. The mercury salt, mercurous thiocyanate, which increases enormously in volume upon being burnt, is the substance from which * Pharaoh's serpents ' are made. It is a strong poison. Two series of alkyl-derivatives are known, one derived from structure No. 1, and another from No. 2, perfectly analogous to the cyanic acid-compounds. The second class are termed mustard oils, from the fact that the most prominent member, allyl-iso-thiocyanate, is the constituent of the seeds of black mustard, and imparts the pungent odour and taste to mustard. Its structure is Fig. 1525 U-X o Mustard oil, allyl-iso-thiooyanate, C4H5NS ; b.p. 151° Mustard oil is present in mustard seed as a glucoside (vide p. 160), potassium-myronate, which, in contact with a peculiar ferment called myrosin (p. 446), also present in the seeds, breaks up into sugar, potassium-sulphate, and allyl-iso-thiocyanate ; the oil occurs also in horse-radish. The movability of the atoms in the cyano-compounds and the consequent ease with which they perform intramolecular changes have already been mentioned. This property has made them most valu- able assistants in chemical syntheses. Thus it is possible through them to prepare from an alcohol an acid that contains one carbon-link more than the alcohol. For instance, methyl-alcohol containing one carbon-atom may be converted into acetic acid containing two carbon-atoms. It is done in this OYANO-DERIVATIVBS 425 way : the alcohol is converted into methyl-iodide and brought together with potassium-cyanide, when potassium-iodide and methyl-cyanide are formed, the two exchanging iodine and cyanogen. Fig. 1526 :l 9. Fig. 1527 -^^ Melliyl-iodide + potassium-cyanide Potassium-iodide + methyl- cyanide or aceto-nitrile When aceto-nitrile is (super-) heated with water, the nitrogen-atom is split off as ammonia, to which the water furnishes the requisite hydrogen-atoms, the oxygen uniting with the rest of aceto-nitrile to form acetic acid : Fia. 1528 Aceto-nitrile + two molecules of water Pig. 1529 #— k© Acetic acid -i- ammonia From acetic acid, ethyl-alcohol may he prepared, and from ethyl-alcohol, propionic acid, and so forth. Such additions of links to a chain are not limited to alcohols and acids ; we can add even two links at once to hydrocarbons, by which method piperidine has been formed from propane (actually from a derivative of propane) in this way : Two cyanogen-groups (of hydrocyanic acid) displace two hydrogen-atoms in propane. Fig. 1530 Fig. 1531 6 4 6 6 6 I i ^^- Hydrocyanic acid Propane Hydrocyanio acid 6 & Tri-methylene-cyanide, C5H5N2 ; b.p. 274° Through" reducing agents eight hydrogen-atoms are introduced into tri-methylene-cyanide, con. verting it into penta-methylene-diamine (fig. 1268, p. 357). Fig. 1582 ? T T T !►— 41 4» i> ©000 Penta-methylene-diamine 426 NITROGEN-COMPOUNDS By heating (of its hydrochloric salt), a molecule of ammonia (ammonium chloride) is split off and piperidine is formed, as we have already seen (fig. 1274, p. 359). It is to these reactions we owe. our knowledge of the structures of the grape-sugar group. When hydrocyanic acid is added to an aldehyde- or a ketone-group, its hydrogen goes to carbonyl's oxygen to form hydroxyl, and its cyanogen group joins the liberated valency, converting the com- pound into a nitrile, which can again be transformed into an acid as already described. Thus if dextrose and levulose are treated both in this same way, the end-products will be two different acids whose structures are well known, and from which we can draw our conclusion as to the structure of the sugars. The following illustrations will make this easily understood : Fig. 1533 a Fia. 1533 E Dextrose Pio. 1533 B Levulose Fig. 1588 F Kitrile of dextrose-carbonic acid Fig. 1538 o Nitrile of levulose-oarbonic acid Fig. 1533 g -O Dextrose-carboxyUc acid Fig. 1533 d o 9 9 9 Q LeTulose-carboxylio acid Fig. 1533 h O G*- Normal heptylic acid ; b.p. 223°; solidifies at -10°-5 Methyl-butyl-acetic acid ; b.p. 212°; is still fluid at -20° FUTUEE NOMENCLATURE 427 Future IsTomenclature of Cyanogen -derivatives When a cyanogen-group forms the end-link in a straight chain of a hydrocarbon, the compound is designated as niinile, and, in the case of two such end-links being present, as dinitrile. The question of nomenclature for similar side-chains is left open for the present. Compounds containing an iso-cyanogen-group are termed cwrbylamines. The name cyanates is reserved for the true compound ethers. Iso-cyanates are termed ca/rhommides. Thiocyanates (sulphocyanates) retain their names. Isothiocyanates become thionecarbonimides. Old NoTnenclature New Nomenclatwre Hydrocyanic acid (fig. 1504, p. 419) = Methane nitrile Methyl-cyanide (fig. 1607, p. 420) = Ethane nitrile Methyl-iso-cyanide (fig. 1508, p. 420) = Methyl-carbylamine Cyanhydrine (fig. 1509, p. 421) = Propane-2 ol-nitrUe Pulminic acid (fig. 1511, p. 421) = Nitroethane-nitrile Cyanetholine (fig. 1517, p. 423) = Ethyl- (ethane?) cyanate Ethyl-iso-cyanate (fig. 1518, p. 423) = Bthylcarbonimide Mustard oil (fig. 1525, p. 424) = 1 Propenyl-thione-carbonimide Rhodanethyl = Ethylthipcyanate We have now come to the end of our structure-illustrations, and gone through, I believe, so far as the structures have been ascertained, all that can have any interest to medical men. There are, besides those compounds we have discussed, a great many more into which phosphorus, arsenic, selenium, antimony, boron, silicon, zinc, tin, mercury, aluminium, magnesium, &c., have been introduced, and whose structures are well known, but they are more of a specially chemical interest, and need not therefore be mentioned in this treatise. Before, however, we go on to mention the most modern development of the law of the linking of atoms, it may perhaps be useful to give a short summary of some compounds of unknown structure, but in which medical science must be deeply interested, such as proteids, ptomaines, leucomaines, and ferments. Paet XI. Prote'ids Ptoraaines Leucomaines AND Fermeiits Proteids Proteids, or albuminous substances, are the only ctemical compounds that we know of existing in the two widely different states, the living and the dead. Our knowledge of the living proteids amounts to next to nothing. The dead proteids only have as yet been accessible to exami- nation by the chemist, and what has thus been disclosed is insignificant in the extreme as regards their structure. They are rather stable, but very complex compounds, the smallest possible empirical formula of a dog's haemoglobin, for instance, being OgggHm^sNig^PeSaOigi (molecular weight 14129), possibly a multiple of these figures. The living proteids, being in a chronic state of building up and pulling down, have probably an extremely unstable and changing structure, and will split into anything required for the anabolic processes. At the moment of their death they entirely change their chemical character and become the more stable compounds, which have been subjected to scientific research. Physiologists have, indeed, been able to demonstrate under the microscope a reducing power in the living proteids which is entirely absent in the dead ones. This and some other considerations have led to the hypothesis that the living proteids partake more of the character of aldehydes, whereas the dead ones have more of a ketonic nature. Some are of the opinion that proteids are formed from formic aldehyde (fig. 633, p. 130) and ammonia as constituents of aspartic aldehyde (4CHOH + NH3 = C^H,N02-l-2H20; vide fig. 1164, p. 326); and that by polymerisation in the presence of sulphuretted hydrogen we should arrive at one of the propounded formulae of albumin, Cj2H,]2N,gS022 ; others consider that living proteids consist of a chain of cyanhydrines (fig. 1509, p. 421) connected with benzene-nuclei. All this, it should be remembered, is mere paper speculation, with but a very slender base of facts. We have firmer ground to tread upon when we come to the dead proteids, though we have not much to be proud of there neither. The great difficulty in all the researches on albuminous substances is that most of them do not form crystalliae compounds, nor has any other properly been ascertained by which we can determine whether we have to do with a single compound or with a mixture of closely related bodies. Quite recently methods have been found to form albuminous substances into crystallisable compounds by combination with ammonium sulphate (Zeitsch/r. f. physiol. Ohemie, 1891, p. 456), and thus we may hope to have in a not distant future more light shed upon these mysterious compounds. The only chemical way we have had to distinguish between different classes of albuminous substances has been their solubility iu different media, and the temperature at which they coagulate. But possibly, and even probably, many of these classes into which we have thus been enabled to divide the proteids contain more than one compound; the often widely different- results to which the several investigators have come, in their ultimate analysis of supposed identical compounds, eeem to confirm such an opinion. Though our knowledge of their structure is nil, it may perhaps be useful to take a short view of their behaviour from a chemical and physiological standpoint, as some of their derivatives have become very popular therapeutical remedies, and their names frequently occur, sometimes employed in a not strictly legitimate way, amongst so-called proprietary medicines. The proteids are divided into two large groups, according as they are soluble or insoluble in water. 432 PEOTEIDS The soluble proteids are termed albumins, the insoluble ones globulins. Both coagulate from their solutions through heat, which is a distinctly different process from /ermsTCi-coagulation, and both again from precipitation, though the words are often used indiscriminately. A precipitated proteid preserves all the original character which it had in solution, and may be re-converted into the soluble form. A coagulated proteid is a new chemical individual which cannot be re-converted into the original substance. The proteids consist of carbon, hydrogen, nitrogen, sulphur, and oxygen. Albumins They, like the globulins, are generally divided into animal and vegetable compounds, but as they do not differ ia their essential characteristics there is no great necessity for such subdivision. They seem to be very sparingly present in plants, whereas they constitute the chief part of proteids in the animal organism. They are distinguished as — 1. Serum-albumin which has been prepared from serum. Three different serum-albumins have been distinguished through the different temperatures at which they coagulate. 2. Egg-albumin differs from serum-albumin in not being precipitated by ether. There seem to be three sorts coagulating at different temperatures. 3. Cell-albumin resembling serum-albumin is found in small quantities in the cells. 4. Muscle-albumin is perhaps identical with serum-albumin. 5. Lact-albumin. Scum of boiled milk is coagulated lact-albumin. These are the more important albumins, but quite a number have, besides, been found in small quantities, each supposed to differ in one way or another from all the rest. Albumin is used as a mordant in calico printing, and therefore prepared on a large scale (chiefly serum-albumin). A solution of albumin mixed with the dye is printed on the cotton ; the colour is fixed by coagulation of the albumin through heating. G-lobulins are insoluble in pure water, and in many concentrated saline solutions, but soluble in the same solutions when diluted. They are the chief proteids in plants, and are, as such, often met with in crystalline form, in which respect they differ from animal globulins, with which they otherwise have all essential characteristics in common. The more important and best investigated globulins are — 1. Fibrinogen, present in the blood, coagulates at a comparatively low temperature (55°) as a characteristically sticky substance. In the presence of fibrin-ferment (vide p. 445) fibrin is formed from fibrinogen by another kind of coagulating process. Fibrin is split by pepsin or trypsin into two globulins. There seem to be three varieties of fibrin. 2. Serum-globulin, formerly called fibrino-plastic, paraglobuUn, and seruTn-cas&in, consists oi a mixture of three globulins : a. Plasma-globulin, pre-existent in the blood-plasma. 6. Cell-globulin, arising from the disintegration of the white corpuscles and the blood- tablets, is probably identical with the fibrin-ferment, c. A globulin arising from the formation of fibrin from fibrinogen. 3. Myosinogen is a globulin in the muscle-plasm that corresponds, without being identical, to fibrinogen in the blood-plasm. It is coagulated and converted into myosin through myosin- ferment (p. 445) analogous to fibrin-formation. This takes place soon after death, and is ALBUMINS, GLOBULINS, NUOLEO-ALBUMINS 433 the cause oi rigor mortis. Besides myosinogen, two more globulins, pwrcvmyosinogen and myoglohuUn, are present in the muscle-plasma, but myosin-ferment does not cause them to coagulate. In plants a globulin is found, very similar to animal myosin : this vegetable myosin is believed to be the precursor of gluten-fibrin, which, by the action of a not yet separated ferment — an albumose — forms gluten by coagulation. Gluten is, according to one authority, not formed from flour by washing when done at a low temperature (2°), which fact would support the hypothesis of a ferment-action. This has been denied by another authority (Gom/pt. Rend. cxvi. p. 202), who has been able to extract 27 per cent, of gluten from flour by water at 0°. Boiling water extracts from gluten a sticky substance called insoluble (sic) phyt-albumose (gliadin, mucedin); the insoluble non-sticky residue ia gluten-fibrin. Vitellin. There is an animal vitellin, ovo-vitellin, and a vegetable one, phyto-vitellin. The latter is distinctly crystalline, and is thus one of the purest proteids known ; still, it leaves an ash of alkaline-phosphates on ignition, and is perhaps a combination of a proteid with lecithin, in which case vitellin belongs to the nucleo-albumins. Crystallin is the proteid in the lens of the eye ; it is very like vitellin in its properties. Oaseinogen is one of the two proteids in milk, the other being lact-albumin. It is like a globulin in some respects, but it does not coagulate by heat. With rennet (p. 445) it coagulates, forming caseiin, provided calcium phosphate is present. Casein is a nucleo- albumin. French physiologists have stated that the milk of blondes contains less oaseinogen than that of brunettes ; this has, however, not been corroborated by other investigators. Cheese is mainly casein with a varying percentage of fats. The ripening is a process of fermentation, or rather putrefaction, brought about by organised ferments. The different varieties of cheese is the result of difference in the bacteria, the various manufacturing places having their distinctive bacteria. Legurain, or vegetable casein, is not present as such in plants. It is an alkali-albumin formed from the native globulins by caustic potash, used in extracting it from plants. A new class of albuminous substances, ' protective proteids,' also belonging to globulins, are described in connection with toxalbumins and ' immunity,' p. 441. COMPOUND PHOTBIDS Proteids, complex as they are, combine with other compounds sometimes still more complex. There are several groups of such combinations ; some of the better known are nucleo-albumins, glyco-proteids, and chromo-proteids. Nucleo-albumins They are widely distributed in animal and vegetable organisms, and consist of proteids, united to a class of compounds called nucleins, containing, besides the usual elements of proteids, always phosphorus, and sometimes sulphur and iron. Cell-nuclei consist of nuclein. The opinions about nucleins are divided ; some consider them mixtures of organic phosphorus- compounds with proteids or proteid-like substances; others are of opinion that they represent chemical units in which an albumin forms the nucleus, surrounded by side-groups (prosthetic groups) containing all the phosphorus-combinations, which can be split off as nucleic acid by alkalies. The most important of nucleo-albumins is casein, which has already been mentioned. F F 434 PROTBtDS Amongst the phosphorised constituents of the organism, the most abundant next to nuclein is lecithin, the only component of vegetable and animal tissues, whose structure has been ascertained. It is a yellowish-white, waxy, hygroscopic solid, which swells and forms a kind of emulsion with water. It is formed from glycero-phosphoric acid combined with fatty acids and choKne. As we have not treated phosphorus-compounds before, it will be necessary to say a little about them now. Phosphorus is an element that in many of its chemical properties resembles nitrogen. It is a pentad, but, like nitrogen, may also appear as a triad. It forms with oxygen and nitrogen several acids, of which we here have to do with the common phosphoric acid only ; it differs in its atomic character from the corresponding nitric acid (fig. 1088, p. 306) in this, that it is tri-basic ; consequently has three hydroxyls and besides an oxygen-atom tied to jjhosphorus by a double bond. Phosphoric acid illustrated would, therefore, appear thus : Pig. 1534 J'hosphorie acid, PH3O4 Phosphoric acid combines with glycerin in regular ether-fashion, forming an ether-acid : Fig. 1535 Glycero-phosphorie acid, CaHgPOj This is the mother substance of lecithin, which latter is formed by joining radicals of fatty acids to the two remaining hydroxyls of glycerin, and choline (fig. 1260, p. 354), through its alcoholic NUOLEO-ALBUMINS, GLYCO-PROTEIDS 435 hydroxyl, to one of the hydroxyls of phosphoric acid. Supposing that the fatty acid-radicals were derived from palmitic acid (fig. 680, p. 177), the structure of lecithin would be illustrated thus : Fio. 1536 Lecithin, C40H82NPO9 Lecithins have been found which contain stearic acid, others with oleic acid, others again with one oleic and one stearic, or palmitic acid-radical, having apparently accepted, or perhaps rather selected, for their formation from such glycerides as were at hand. Lecithin is nearly ubiquitous : it occurs in the nervous tissues, in the blood-corpuscles, in moat organs of the body, in secretions such as semen, bile, milk ; in fact, in every growing cell or wherever cellular elements exist. If it is not found isolated it is still present in combination with other bodies. It originates in plants and enters through them the animal organism. It must be looked upon as stored-up capital upon which the organism incessantly draws for supplies of repairing materials, containing, as it does, phosphorus- and nitrogen-compounds, and fats needed for such purpose. It is certainly the intermediate link between the inorganic and organic forms of phosphorus in the mineral and animal kingdoms. Some similarly constructed compounds are the protagons, found in the brain. Their structure is much more complicated, and contains sulphur besides the constituents of lecithin: carbon, hydrogen, oxygen, nitrogen, and phosphorus. Barium-hydrate splits off from protagons two compounds, cerebrin and herasin, probably glucosides. Both contain fatty acids, which are present in cerebrin in the proportion of three molecules to every two atoms of nitrogen. The empirical formula of cerebrin is probably 0^^^^^fi^^, and that of kerasin OjoHjgjN^Oij (Ztsch. f. physiol. Ch. xvii. p. 431). Grlyco-proteids are combinations of proteids and some reducing compounds belonging to the class of carbo- hydrates or substances easily converted into them. Through the action of dilute acids glyco- proteids are easily split into these components. To them belong — Mucins. The best known is that contained in saliva, a slimy substance secreted by the sub- maxillary gland for the purpose of lubricating the food, thus protecting the pharynx and oesophagus during the process of swallowing. V s 2. • 436 PROTEIDS Ohromo-proteids are split into proteid and pigment. Haemoglobin, the pigment of the red blood-corpuscles, contains iron, and ia cryatallisable. It consists of a proteid, a globin (probably a mixture of proteids), and a pigment hcematin. Although it is crystallisable, the analyses of different observers are too discordant to make any probable calculation from them; one, for instance, being OgjgHjjjNi^gFeS^Oi^g, and another, OjiaHnjjNji^FeSijOj^g. ..... It unites readily with oxygen, molecule for molecule, and gives it, off again as easily^ actmg both as an oxidising and as a reducing agent. It is therefore the great oxygen-carrier of the body, one gramme combining with nearly 1'3 c.c. of oxygen. There is not much of it by weight in each corpuscle, the amount having been calculated to thirty billionths of a gramme, but then there are five millions of corpuscles in every cubic millimetre of blood. The combination of haemoglobin and oxygen is called oxyhaemoglobin, which is formed in the lungs and carried all over the body, where a breathing process is actually performed by the protoplasm in the cells. Prom haemoglobin the pigments of the bile are formed : bilirubin (biUfuhiin, cholepyrrhihy biliphcBin), G^^TS^gNfi^, and biliverdin, OjHgNOj. Likewise the pigments of urine and faeces. Other pigments, about which scarcely anything is known, are — Lipochromes, or fatty pigments, such as carrotin in carrots. Chromophanes in the eyes of birds, fishes, &c. Serum-lutein, the pigment in serum. Chlorophyll probably contains lecithin. It has been split into a yellow pigment, jphylloxan- thine, and a blue, phyllocyanine. Chlorophyll is supposed to form aldehydes in plants by decomposing the carbonic acid and water present in the atmosphere ; and carbohydrates by polymerisation of aldehydes {vide fig. 622, p. 153 ; also fig. 541, p. 132, and fig. 569, p. 189). Melanin is the black pigment produced from haemoglobin when the red blood-corpuscles are entered and eaten away by malaria parasites ; moreover, any black pigment of the body is termed a melanin; sometimes a precursor, melanogen, has been found. ALBUMINOiDS are a class into which all substances are thrown that do not fit any of the classes already mentioned. Prom a chemical point of view there is scarcely more to do than to enumerate some of them. Keratin, the horny material of the animal body, such as nails, hair, hoofs, &c. Skeletins: GJdtin occurs in the invertebrate-group. GoTicMolin in the shells of gasteropoda. Spongin forms the skeleton of sponges. Fibroin is the spider's web. Silk consists of two cylinders, one inside the other ; the outer one — Seridn — is removed by boiling water, in which it is soluble ; the inner cylinder is fibroin, or something like it. Collagen, the substance of which the white fibres of connective tissue are composed. The- same substance in the bones is termed ossein. Gelatin is produced by boiling collagen with water. Elastin is the substance of which the yellow fibres of connective tissue are composed. Spermatin, the mucin-like substance (but not a mucin) in semen. CHEOMO-PROTEIDS, ALBUMINOIDS 437 Any classification of compounds, about which we know so little as we do about albuminous matters, must necessarily be but provisional and dependent upon the view of their composition taken by individual investigators ; there are, therefore, several more or less diverging classifications in existence. The classification worked out in the preceding pages has for its object to place the much concentrated matter before the reader as intelligibly as possible, and has therefore not slavishly followed any individual opinion. For the English view on the matter I am indebted to the excellent work, Halliburton's Chemical Physiology and Pathology, from which several quotations for which I could find no happier expression have been borrowed literally. For the way, however, in which these quotations have been used I alone must be held responsible, for which reason these loans have not been specially indicated. PHTSIOLOaiOAL DB-FORMATIOISr AND RE -FORMATION OF PROTEIDS The prote'ids are exclusively formed in plants; some of the theories of their formation have already been mentioned (p. 431). From plants they go over into the animal body as dead or coagulated proteids unfit for absorption and assimilation ; therefore they undergo in the digestive organs a process by which they are converted from an indiffusible state (colloids) into a diffusible (crystalloids), depolymerised or, as it were, stripped of their clothes in order that they may be able to slip through the mucous membranes and pass into the circulation. Once on the other ^ide of the membrane they again put on their clothes without delay, perhaps a little altered to suit the new circumstances, and are then ready to be initiated into the mysteries of the protoplasm of the cell, where they receive anew the life which they lost by parting from their mother plant. Such is, in short, the history of the proteids until they have become assimilated with the protoplasm of cells. The conversion of indiffusible into diffusible proteids is, however, performed in several stages. From proteids they are turned into less indiffusible proteoses, and these again into easily diffusible and soluble peptones. These are only the main features of their transformation, with proteids and peptones as the beginning and the end. As no collective names have yet been coined for all proteids in their several stages of transformation, I will select albumin as the body that has been best studied. Albumins either consist of, or are split by pepsin into, two kinds, anti-albumin and hemi- albumin. Each of them is by the further action of pepsin converted into two different products, of which one is common to both, so that at this stage of the action there are three different com- pounds: 1, anti-alb uminate (acif^aZftwrnm) ' from anti-albumin ; 2, (hemi-) proto-albumose from hemi-albumin ; and 3, hetero-albumose from both. While the last two remain unchanged for a time, the first, anti-albuminate, makes a further step by transformation into anti-albumid. The three substances we now have are therefore: 1, anti-alburmd ; 2, (hemi-) proto-albumose ; and 3, hetero-albwrmse. By yet further action of pepsin these three are converted into 1, anti-deutero- albumose; 2, hemi-deutero-albumose ; and 3, ampho-deutero-albumose ; and by pro- longed action into 1, anti-peptone; 2, hemi-peptone; and 3, ampho-peptone. ^ The same compound (also termed syntonin)is formed by the action of acids upon albumin. Through the action of alkali another compound is formed, called alkali-albumin. Corresponding compounds are formed from globulins. Their collective name is albuminates. 438 PEOTEIDS These processes are represented by the foUowing^ table : — Albumin Anti-albumin Hemi-albumin I I Anti-albuminate Hetero-albumose Hetero-albumose Proto-albumose Anti-albumid Anti-deutero-albumose Ampbo-deutero-albumose Hemi-deutero-albumose I I ! Anti-peptone Ampho-peptone Hemi-peptone (From Halliburton's Ohemical Physiology.) Anti-peptones are not further acted upon by pepsin or trypsin ; they are absorbed by valvulse conniventes and -villi, and during the passage through the mucous membrane of the intestinal wall, or at least on entering the lymph, they put on their clothes (to stick to the homely simile), and appear as regenerated and probably improved albumins, for there are no peptones found in the blood ; they, as well as the albumoses, are even strong poisons if they happen to get into the blood unaltered. Hemi-peptones are further acted upon by trypsin (not by pepsin), being disintegrated into a variety of products, of which the more important are leucine (fig. 1160, p. 325), tyrosine (fig. 1168, p. 327), aspartic add (fig. 1163, p. 325), ammonia, and some compounds of unknown structure. The other protei'ds are similarly acted upon by the digestive ferments and formed into globu- loses : vitelloses, myosinoses, caseoses, &c. Many protei'ds, albumoses, and peptones are poisonous, those about which we know the least have been collected in one class, toxalbumins (p. 441). , The fermentative action is by some investigators described as a hydration process (introduction of the elements of water), by others as a depolymerisation, but not much is known to support either of these propositions. As peptones, peptonised milk, meat, &c., have become the fashion of the day, it will be useful to remember that commercial peptones are not peptones at all, but invariably proteoses. The taste of real peptones is extremely disgusting, therefore one cannot expect to find them in the commercial article. Albumoses are separated from peptones by a concentrated solution of ammonium sulphate, in which the former are soluble, the latter not. The different sorts of albumoses have been recognised and isolated through their solubility in water and in a solution of sodium-chloride ; still, they must not be considered distinct chemical bodies, because of their having been entered in the nomenclature as such ; in all probability they are mixtures, the chemical character of which may be very different from that of the components. Only very recently (Monatsh. xiv. 1893, p. 612) a crystalline com- pound.has been isolated, which seems to be a distinct chemical compound, the first free albumose ever prepared. Insolubility in alcohol has hitherto been considered one of the characteristic properties of albumoses, but this one was soluble ; its molecular weight as determined by Raoult's method was surprisingly low, varying from 587 to 714, though the ultimate analysis pointed to upwards of 2000, when calculated on one atom of sulphur as present in its structure. Hffimatogen is an albuminate present in eggs and probably in most kinds of food, and contains 0-29 per cent, of iron, which is not directly precipitated by ammonium-sulphide. Ferratin is a similar albuminate found in the liver, derived, no doubt, from hasmatogen, and is supposed to provide the necessary amount of iron required for the formation of the red blood-corpuscles. Commercial ferratin is an imitation of the natural product, and prepared by prolonged reaction of iron-salts on alkali-albumins. PROTBIDS 439 CHEMICAL AND BACTERIAL DISINTEaRATION OF PROTEIDS It has been already stated that the structure of a chemical compound is arrived at by examining the decomposition products, i.e. pulling it to pieces and afterwards trying to get the original compound by putting the pieces together again. Of course that has been tried with the proteids, and the breaking up has been eminently successful ; in fact, not many other organic com- pounds are so sensitive to chemical agents ; and as regards bacterial agents the facility with which albuminous matters break up is simply astounding. But putting Humpty Dumpty together again is a very different thing, and has not yet been even approached. And do we wonder when the eye runs down the list of fragments comprising almost the whole of organic chemistry as it was known fifty years or so ago ? The following is a list of some of the products obtained by the three agents, destructive distilla- tion, chemical and bacterial actions. The figures refer to the pages in the foregoing treatise, where^ the structure of the compounds or of similar compounds will be found. PAGE Phenol 92 Cresols 95 Acetaldehyde 131 Butyraldehyde 132 Acetone 138 Carbohydrates 151 Formic acid 175 Acetic acid 175 Propionic acid 176 Valeric acid 176 Caproiic acid 177 Palmitic acid 177 Carbonic acid 179 Glycollic acid 179 Lactic acid . . ^ 179 Oxalic acid 184 Succinic acid 185 Acrylic acid 190 Orotonio acid 190 Oleic acid 192 " Fumaric acid 195 Benzoic acid 211 Phenyl-acetic acid 212 Hydro-oinnamic acid 212 Phenyl-propionic acid 213 Hydroxy-phenyl-acetie acid 215 Hydroxy-phenyl-propionic acid 215 Hydro-coumaric acid 216 Furfurol 260 PAOK Sulphuretted hydrogen 280 Methyl-mercaptan 281 Nitro-benzoio acid 306 Ammonia 312 Aniline 313 Trimethyl-amine . 315 Ammonium carbonate 323 Ammonium sulphide 323 Ammonium cyanide 323 Amido-valerio acid 325 Alanine 325 Aspartic acid and its homologue, glutamic acid . 325 Leucine 325 Leuceine 326 Amido-benzoic acid 326 Tyrosine 327 Phenyl-amido-propionie acid 327 Pyrrol and homologues 329 Indole 352 Skatole 352 Creatine and its homologue, lysatine . . . 374 Creatinine and its homologue, lysatlnine . . . 375 Uric acid 376 Hypoxanthine and adenine 377 Guanine 377 Pyridine bases 391 Hydrocyanic acid . ..... 419i Ptomaines &o 440 Visitors to the British Museum are generally shown the Portland Vase as a masterpiece of high-art patch-work. I wonder what the artist would have made out of the above pieces— scarcely albumin. 4i40 PTOMAINES AND LEUCOMAINES Ptomaines and Leucomaines Ptomaines and leucomaines may be called animal alkaloids in contradistinction to vegetable alkaloids. As we have no strict definition of the latter there is still less any of the former. Vege- table alkaloids are generally spoken of as compounds of basic and poisonous character, with a nucleus of pyridine, i.e. cyclo-ammonia-bases, but there are alkaloids said to be only distant relations of pyridine, e.g. morphine and codeine. Of the constitution of animal alkaloids we know but little ; those few of which we do know the structure are either ammonia-bases with open chains or ammonium-bases, formed from the urea-groups ; but to build any definition upon these solitary facts would be premature. Ptomaines and leucomaines have been described as basic compounds produced in the tissues of animals, the former being products of abnormal life-processes (exchange of material, Stofi"- wechsel) in diseases, or the result of bacterial agency after death,* the latter produced during life by normal metabolic processes. But as many of them are common to both processes, no shai-p line can be drawn in this way. Some are virulent poisons, others quite innocuous, but it would not materially assist us if we were to make poisonous nature the line between them, as most ptomaines are poisonous, and many leucomaines likewise, even when passing through the alimentary tract. The difficulty is made still more acute by the fact that there are many compounds which can go all the way through the digestive organs without doing any harm, but are deadly poisons if injected into the blood-circulation ; and the same substance may frequently, by difierent authors, be styled a ptomaine, a leucomaine, or a toxalbumin, sometimes even by the same author, and it is quite a common thing to write about ptomaines produced by bacteria, in anthrax, puerperal fever, hydro- phobia, &c., and formed during life. The safest thing to do in present circumstances is to simply enumerate these compounds as ptomaines and leucomaines without giving any reasons for such classification. The empirical formulae if .known will be added, though it is only a poor idea of their constitution which they suggest, and some may be liable to correction. Ptomaines ose structures are known, viz. — Betaine, fig. 1265, p. 355 Putrescine, fig. 1267, p. 357 Cadaverine and neuridine, fig. 1268, p. 357 Methyl-guanidine, fig. 1336, p. 374 OoUidine and hydrocoUidine (copellidines, p. 397), fig. 1418, p. 392 Parvoline, p. 393 Propyl-amine, fig. 1110, p. 313 Di-methyl-amine, fig. 1115, p. 314 Tri-methyl-amine, fig. 1121, p. 315 Tyrotoxicon, fig. 1213, p. 337 Choline, fig. 1260, p. 354 Neurine, fig. 1261, p. 354 Muscarine, fig. 1262, p. 355 Unknown structures : Saprine, 0gH,gN2;tetanotoxine, OgHjjN, secretion from bacillus tetani; tetanine, OijHgjNjO^, from the same bacillus ; typhotoxine, CjHijNOj, from the typhus bacillus; mytilotoxine, OgHigNOj, the poison in mussels; gadinine, CjE^NO^, from putrid cod-fish. In cod-liver oil, prepared from putrefied liver, several ptomaines were found: butylamine, ' Ptomaines do not always appear to be directly produced by bacteria, but through the action on albuminous substances of a ferment-enzyme discharged by them. PTOMAINES 441 iso-amylamine, hexylamine, OgHj^N; di-hydro-lutidine (comp. p. 393); asseline, OjgHjgN^; and morrhuine, OigHjjNg, all of wMcli are bacterial decomposition-products from albuminous substances in the cells and connective tissues of the putrid liver, perfectly ana- logous to cheese and sausage poisons ; consequently ptomaines and not leucomai'nes from the bile, as demonstrated in my ' Ooncluding Bemwrks ' in the first part of this book. Leucomaines The difficulty met with in an enumeration of compounds which may be considered under this head is, as I have said before, to draw the line. A great number may be included, or but a few. I will give the names of the few, proceeding as before. Creatinine (lig. 1339, p. 375); xanthine (fig. 1347, p. 376); hypoxiEtnthine or sarcine (fig. 1348, p. 377); adenine (fig. 1349, p. 377); guanine (fig. 1351, p. 377); carnine, OjHjN^Og, supposed to he di-^methyl-iwea ; pseudoxanthine, OjH^N^O^, isomeric with xanthine, two carbon-links and a nitrogen-link exchanging places (others give the formula O^HgNgO, in which case it is, of course, not an isomer of xanthine); para-xanthine, 0,HgN402 (isomeric with theobromine, fig. 1352, p. 378); xantho-creatinine, OgHj^N^O ; cruso-creatinine, OgHgN^O; amphi-creatinine, OgHijNjO^ ; samandarine, CggH^^NjOig, the basic poison of the salamander; most of them have been separated from muscle, some also from urine and fasces. During waking hours some leucomaines of a soporific nature are said to be formed, and during sleep others, which are stimulants ; thus when a sufficient amount of the first sort has accumulated we get sleepy ; the others make us wide awake. Physiologists have several other, of course non- chemical, theories. They are all about equally well founded. Toxins and Antitoxins Besides the basic compounds just described as originating from normal and abnormal processes in the organism, some albuminous substances owing their existence to the same causes have also been discovered. Some of them, poisonous, are termed toxins or toxalbumins; others protect the organism against the activity of the former, and are therefore termed antitoxins. Amongst toxins produced by normal life-processes may be named: Snake-poisons (cobra, viper, crotalus, copperhead, and moccasin) ; abrin, a poisonous proteid (consisting of a globulin and an albumose), from the fruit of Abrus precatorius (jequirity) ; ricin, a proteid from the seeds of Miciivus cow/mums. Toxins abnormally produced in the organism by bacterial activity are, for instance: Anthrax- protein, from the anthrax bacillus ; toxo-peptone and toxo-globulin, from the cholera bacillus; toxo-mucin, from bacillus tuberculosis; in several instances arrow-poisons have been recognised as albuminous substances, and belong probably to this class. The toxic properties of toxins in solution seem to be destroyed if exposed for some ten hours to the sun's rays, or for a couple of hours to a constant electric current, but no such effect is produced upon the dried toxins by these agents. The toxins are supposed to be the real cause of the various diseases from which the bacilli derive their names ; but it has been found that some organisms are able to kill certain bacilli or neutralise the poisonous toxins which they produce ; for instance, negi'oes are proof against the bacillus of yellow fever, and so are rats against vibrio Metschmkowi : this state of the organism is called imrmmity as regards that disease, and recent researches have established the presence of albuminous substances in the blood of such animals, which are believed to protect the organism against the diseases that the respective bacteria otherwise would have caused. It has further been ascertained that pathogenic bacteria themselves produce, besides their particular poison, an albuminous substance which, if separated and injected into the blood, protects the organism in a similar way. When an 442 TOXINS AND ANTITOXINS animal has been thus made immune, it has been found that the blood-serum of such animal, when injected into the circulation of another, makes this second one also immune ; even milk from the first, subcutaneously injected into other organisms, is sufficient to produce immunity; further, it appears that one animal can at the same time be made immune against several diseases by simul- taneously injecting the secretion of different bacteria ; the blood-serum or milk of this animal wUl then, by injection, make another, proof against all the diseases ordinarily produced by the respective bacteria employed. These albuminous substances, whether found as normal products or created artificially in the blood, are distinguished as antitoxins, protective proteids, vaccines, or alexines ; physiologically they have been divided into sozines, those found in animals naturally immune, and phylaxines, those found in animals which by subcutaneous injections have artificially been made immune. Sozines are again divided into mycosozines, which protect by killing the bacteria, and toxosozines, which act as antidotes to the poisonous excretions of bacteria. Phylaxines are similarly divided into mycophylaxines and toxophylaxines, according as they destroy bacteria or their poison. Sozines seem to live in the cells, whereas phylaxines are apparently in solution in the liquids of the organism (Gentralbl. f. BaJderiol. 1891, x. pp. 337, 349, 377). Several antitoxins have already been prepared, though not in the isolated state. Of phylaxines may be mentioned: Tuberculin and the purified products tuberculocidin, tuberculinic acid, tuberculinose, and antiphthisin, from bacillus tuberculosis; mallei'n, preparedfrom glanders ; antidiphtherin, from the diphtheria bacillus; antitoxin, from the typhus bacillus; anti- cholerin, from the cholera bacillus; cancroin (from the supposed cancer bacillus) is now considered identical with neuridine, a ptomaine. Amongst sozines may be counted : Oar din, extracted from the heart-muscles of cattle; cerebjin, from the brain; sequardin, from the bull's testes (comp. spermine, p. 358); nuclei'n, from the spleen of calves. The investigations on toxins and antitoxins are quite in their infancy, groping in the dark ; the importance of supposed discoveries is generally grossly over-estimated by the discoverer and his followers, and the anxiety to be the first in the field leads to so many badly founded and foregone conclusions that the above representation of the present state of this part of the science will probably be of little value in a short time. FERMENTS 443 Ferments Under the collective name of ferments are classed a large number of bodies of which chemically we know nothing except that, without, themselves, apparently undergoing any chemical change whatever, a small quantity may aflfect the constitution of a large quantity of certain other chemical compounds. Some of them are living organisms, others chemical compounds ; but the action of both is of the same nature, viz. breaking up larger molecules of those compounds with which they come in contact into smaller molecules ; each ferment has, as a rule, the power to act upon but one special class of compounds, and in cases where more ferments have the power of acting upon the same compound, they generally do so in different ways. They are divided into two large groups : 1, organised ferments, and 2, unorganised ferments or enzymes. OBG-ANISBD FERMENTS comprise a large number of the lowest class of plants, unicellular organisms, belonging to fungi, such as toriil^ and bacteria. Their action upon chemical compounds is called fermentation, which term also includes the action of unorganised ferments. They are chemically classified according to the sort of fermentation they produce ; the principal of these are: 1, alcoholic; 2, acetic; 3, lactic; 4, butyric; and 5, mucous fermentation. Of course bacteriologists have several classifications of their own. Prom a chemical point of view there is not much more to say about this group, without going too far into details, except it may perhaps interest some to know — nervous people, beware ! — that, with every mouthful of bread-and-butter, we swallow as many microbes as there are inhabitants in Europe — say three to four hundred million. TJNOEaANISED PEBMENTS are true chemical compounds, the product of the activity of living cells. Their constitu- tion is entirely unknown, none of them having as yet been isolated in a perfectly pure state. They resemble, however, in many respects the proteids, which, as we now know, is not saying much ; indeed, our wisdom may be put into a nutshell : some ferments have been recognised as aldehyde- like compounds. In the absence of any knowledge, of their chemical constitution they also are classified according to the effect they exert upon other compounds, and may consequently be divided into— 1. Proteoh/tio ferments, which change proteids into peptones. 2. Amylolytie ferments, changing amylose (starch &c.) into sugar, 3. Inversive ferments, converting cane-sugar into glucose. 4. Steatolytic ferments, splitting fats into fatty acids and glycerin. 5. Goagulative ferments, converting fibrinogen, caseinogen, myosinogen, &c., into fibrin, casein, myosin, &c. 6. Ohicoside-splitting ferments, splitting glucosides into glucose and other compounds. 444. FERMENTS Proteolytic, Proteo-hydrolytio Ferments All unorganised ferments are formed in the secreting cells of the living organism, selecting from the lymph certain materials, which are worked up by the protoplasm of the cell into a secretion termed zymogen, and discharged into the lumen of the gland of which it forms part. During the discharge this zymogen is converted into the ferment zyme or enzyme, which is the ferment that acts upon the proteids. Sometimes the ferment is formed without its precursor zymogen, or, may be, the latter has as yet escaped detection. We shall mention some of these ferments and their precursors. Pepsinogen is formed in both the pyloric and the cardiac glands of the stomach. On leaving the cells it is converted into a proteid pepsin, and is as such discharged into the stomach. Pepsin converts the non-absorbable proteids through a series of intermediate products, proteoses, into the absorbable peptone ; it can, however, do so only in the presence of an acid. In the stomach this acid is hydrochloric acid, which is produced by the parietal cells of the cardiac glands. The dis- charge from the glands into the stomach is, as a whole, called gastric juice, which, however, contains other ferments than pepsin. Trypsinogen is formed in the pancreas cells and leaves them as trypsin, which is discharged into the duodenum. It acts similarly to pepsin on proteids, but more rapidly and best in an alkaline solution, and also, but not so well, in a neutral one ; it wUl not act at all in an acid medium, and is destroyed by hydrochloric acid. Salicylic acid does not hinder the action of the ferment. The discharge from the pancreatic gland is alkaline, and called pancreatic juice: this contains also other ferments besides trypsin. Papain or papayrotin, obtained from the juice of the papaw plant (Gwrica papaya), also from figs and melons, converts animal proteids into proteoses, and finally into peptones. It works in a neutral medium, but best in a slightly alkaline solution ; the smallest quantity of hydrochloric acid is inhibitory, and papain therefore cannot be used as a substitute for pepsin. Vegetable proteids are not converted by it further than into proteoses. Papain is only one instance of proteid-splitting ferments occurring in plant tissues ; probably such ferments are present in all, especially in carni- vorous plants ; one has been found in pineapples, which, unlike papain, acts in a slightly acid solution, and is rendered inactive by alkalis. Pepsin and pancreatin (the dried gastric and pancreatic juices from animals, such as pigs, sheep, or calves) are now prepared on a large scale. Pepsin acts probably as a carrier of hydro- chloric acid, and, having delivered the acid to the proteid, is regenerated into pepsin, ready to serve again as carrier. A small quantity of perfectly pure pepsin should be able to convert an unlimited quantity of proteids into peptones ; none so pure has as yet been prepared, but immense improve- ments have taken place. Pepsin that will dissolve 10,000 times its own weight of albumen, or even more, is already prepared {Sitzung d. ph. Gesells. in Berlin, February 2, 1893 ; Ph. G. xxxiv. p. 92). The requirements of the B.P., 1885, were satisfied with 1 : 50. Amylolytic Ferments Ptyalinogen is the ferment-precursor formed in the three salivary glands, the parotid, the submaxillary, and the sublingual. Ptyalinogen appears in saliva as ptyalin, a ferment that converts starch into dextrin, maltose, and some glucose ; it has no action upon cellulose, conse- quently none on uncooked starch-grains, and an acid stops its activity altogether. The influence of saliva upon the secretory and motory action of the stomach is greater when it has been mixed with the food in the mouth before it enters the stomach than when separately brought there through a tube (Zeitschr. f. Tdin. Med. xxi. pp. 1, 2). FERMENTS 445 Amylopsin is a ferment discharged together with trypsin from pancreas. It has the same action as ptyalin upon starch, converting it into maltose, and by some investigators is considered identical with it. It is not indispensable to the digestion and resorption of carbohydrates, but it has been experimentally demonstrated that grape-sugar is carried ofiF through the urine in its entirety without any transformation after extirpation of both the salivary glands and the pancreatic gland. Diastase, a proteid, is a ferment always present in small quantities in plants, but specially abundant in seeds during germination. There seems to be two forms of diastase : tromshcaUon- dmstase, which acts by dissolving the starch-grain evenly, and as' a whole ; and diastase of secretion, which eats away the starch-grain" in a very irregular manner ; both, like ptyalin, convert starch into sugar. Inversive Ferments Invertin (invertase, zymase) is extracted from certain kinds of yeast. It splits cane-sugar into dextrose and levulose. Glucase is present in non-germinating seeds in a soluble form. It converts dextrin into dextrose. Succus entericus contains one or more similar ferments, converting cane-sugar into dextrose and levulose, maltose into glucose, milk-sugar into dextrose and galactose. This class and the amylolytic ferments are sometimes lumped together under the name of carbohydrate enzymes. Steatoljrtic Ferments, or G-lyceride-enzymes Steapsin. — The existence of this ferment is inferred from the action of pancreatic juice on fats. It has never been isolated. Seeds contain similar ferments, which during germination split up the oils in them; such ferments have been found in the seeds of rape, poppy, hemp, maize, and Bicinus convnunis. Coagulative Ferments Their action is probably not always to break up but often to build up, either from two different compounds or by polymerisation from one compound. Fibrin-ferment is derived from the disintegration of the white blood-corpuscles and tablets after the blood has left the organism, and is probably a globulin. The addition of this ferment to fibrinogen causes the formation of fibrin by coagulation. Myosin- ferment corresponds exactly to fibrin-ferment, causing in the same manner the formation of myosin from myosinogen, a proteid found in the muscle. Myosin-ferment is probably an albumose. Rennet (chymosin) is a similar ferment, formed together with pepsin in the pyloric and cardial glands, and together with trypsin, amylopsin, and steapsin in pancreas. It is generally prepared from the mucous membrane of the fourth stomach of the calf; several plants contain ferments, which have a great resemblance to rennet, and in some localities are used for curdling milk. Through the action of rennet a soluble proteid present in milk, called caseinogen, is converted into the insoluble proteid casein (curdling or clotting milk). Gluten-ferment, hypothetical, is supposed to convert some pre-existent proteids in flour into gluten. 446 FERMENTS Gliicoside-splitting Ferments Emulsin, or synaptase, present in bitter almonds, will split several glucosides; thus amygdalin, a compound occurring in bitter almonds, is split up into oil of bitter almonds, hydrocyanic acid and glucose; salicin, found in varieties of salix, into saligenin and dextrose, p. 160; coniferin into coniferyl-alcohol and dextrose (ibid.) ; cesculin into eesculetin and dextrose (ibid.), &c. My rosin, found in the seeds of black and white mustard, and in orudferce generally, breaks potassium myronate up into potassium bisuJphate, mustcurd^oil, and dextrose (p. 424). It is peculiar inasmuch as it does not require the presence of water in the reaction. There are many other enzymes of which we know little more than their existence, for instance : Histozyme in the kidneys splits hippuric acid into benzoic acid and glycocoll, which seems strange when we remember that hippuric acid is formed when carnivorous animals (including man) are fed upon benzoic acid (p. 330). By torula urese is produced an enzyme which transforms urea into ammonium carbonate. The anthrax bacillus produces an enzyme that forms albumoses from fibrin. The cholera bacillus is the origin of an enzyme, which forms sugar from starch, peptonises proteids, and coagulates milk &c. Part XII. Atoms A CHAT ABOUT ATOMS We have now handled atoms and molecules so long that curiosity may be excused when raising the question, what they really are, and what they look like. Well, no one has ever seen, or will ever see, them, so it seems a rather hopeless question to put ; still human ingenuity is great, and it is almost incredible what wonderfully constructed fabrics it can build from a few bricks of facts. We will give them a short review. It is well known that gases expand when the temperature is raised, and contract if it be lowered, and it has been ascertained that all gases expand or contract equally at equal changes of temperature. This dilatation or contraction has been found to be a constant fraction of its volume for each degree of altered temperature, and that this constant is -j-fg- of the volume of any gas. Suppose, then, we have a gas which at 0° measures 273 units of volume, it would at —1° measure 272; at —2°, 271 units; and at —273° (which temperature is termed the absolute zero) its volume would be 0, pro- vided the law holds good at all temperatures. It has, therefore, been said that atoms were nothing but motion, which at —273° would cease, and matter would vanish like a ball in a conjurer's hand — only more thoroughly. This theory has not met with general approval, as there are a good many well-founded objections to its acceptance, amongst others that the above law is applicable only within narrow limits. The most recent theory of atoms is the so-called vortex hypothesis. Besides the matter we can see or feel, other matter is supposed to exist, filling the whole space, but not accessible to our senses. The necessity of assuming its existence is a consequence of the nature of forces. If a force acted on a body at a distance, without any intervening medium, the action would be instantaneous, i.e. not occupying any time for traversing the intervening space. But ever since the days of Rom er, we know that light takes time to travel through space ; and lately it has been shown that electro- dynamic action also requires time, and, indeed, the same time as light for its propagation from one point of space to another. This can only be explained by the existence of a medium, which has been called the ether. It is a rather funny sort of matter, which, though material, does not possess the properties of ordinary matter. It is neither a gas, nor a liquid, nor a solid ; still it has at the same time something of the nature of these three : it has penetrability like a gas, only in an infinitely higher degree, as it pervades everything, gases, fluids, and solids; it has mobility like a fluid in so high a degree that it may be regarded as a perfect fluid, i.e. one which is entirely devoid of internal friction, an ideal fluid" which does not elsewhere exist in nature. Finally, it has one property exclusively belonging to solids, viz. rigidity ; a thousand millionth of that of steel, it is true, still rigidity ; and its density is, as an oSset, a hundred trillion times less than that of steel. Such is the ether, if there be any at all. In and from this ether it is that the atoms have been formed by it having ' once upon a time ' been set in rotatory motion; and once set rotating it will always remain so, since there is no interna] friction. The rotating parts of the ether, or vortices, as they are called, are, if singly, the atoms, or, if linked, the molecules. A smoke-ring, such as some tobacco smokers can produce to perfection, is an illustration of a simple circular vortex-atom. An apparatus which produces these G G 450 ATOMS smoke-rings from ammonium chloride has been constructed in order to study their properties. When a ring is sent out of the apparatus it advances revolving — as a string will do when rolled between the fingers — with diminishing speed, on account of friction with the air, and growing in size until it stops and disappears. But if a second ring be projected directly after the first, in a slightly diverging direction and at a somewhat greater speed, it will, of course, overtake the former, but they will not collide ; they will move alongside each other, vibrating like an elastic ring after an impact. If the second ring is sent ofi" exactly in the same direction, it will, when approaching the first, grow smaller, and finally pass through if it has sufiBcient speed ; if not, they will remain one inside the other, both revolving all the time, representing a molecule in the ether, while a single ring repre- sents an atom. The rotatory motion of the rings produces in the surrounding ether corresponding currents, which, following the direction of the rotation, flow forwards through the interior of the ring and backwards on the outside, like the wire round an electro-magnetic ring ; these currents then re- present the sphere of action round an atom or a molecule, and give a ready explanation of the phenomena mentioned above. Thus the second ring remains inside the first, because the current on the outside of one vortex is opposite to the current on the inner side of the other, the speed of both being equalised. It is on account of the same currents that actual collision between two molecules is prevented, and that the division of an atom or ring is impossible, because nothing can come near enough to touch it in a perfect fluid like the ether. We have before discussed the three difierent states of matter, and need therefore only repeat that these vortices have the two motions specified in describing the smoke-ring, a revolving and a forward motion. In the solids, where the vortices are sufficiently close for the currents to touch each other, the forward motion is, as a consequence, changed into another sort of revolving motion, one vortex (or combination of vortices) whirling round another. When solids are converted into liquids the proximity is not so great, although the revolving motion is continued, and more freedom therefore is allowed to the individual molecules, though, surrounded as they are on all sides by other molecules, they cannot entirely free themselves, and resume their straight path except on the surface, where escape is possible for some of the molecules, which process we call evaporation.' Some of these released molecules will collide and be thrown back into the liquid (condensation), and the number of these increases with the number of escapes. When just as many are thrown back as escape, the space above the liquid is said to be saturated. In the gaseous state the vortices are removed from one another far beyond the influence of their currents (sphere of action), and therefore resume their original straight paths in all directions. A consequence is that they frequently collide and rebound like two billiard balls, and comparatively- few reach the boundaries of the gas to exert, through their impacts, the gaseous pressure upon the walls of the enclosing vessel. These collisions prevent a joint and simultaneous attack of the molecules, which would be disastrous to whatever might happen to be in their way. It has been calculated that if all the molecules of the air inside an ordinary room could be directed in parallel paths, there would be exerted a sudden pressure of several thousand horse-power — sufficient to shatter the walls into atoms. If we possessed handy means to effect this change of direction — something like the ' Vril Staff' in the convenient form and size of a walking stick, as described by Bulwer in The Oondng Race — there would be good reasons for the nations to disarm, and excellent prospects for the ' eternal peace.' As it is, revolvers, guns, cannon, dynamite, and other crude arrangements, working upon the same principle, have proved insufficient for the purpose, or worse than that. The movements of the atoms or molecules are very rapid, and their size is so minute as to be almost beyond conception. A gas molecule moves at a speed of over 500 yards per second ; that is, the same as that of a rifle bullet or a point in equator. Although rapid enough, still it is not much compared to that of light and electricity (when propagated through space), which is 40,000 miles per second. But the collisions of a molecule with others are 5,000 million per second, and it passes by sixty-two other molecules between each collision, or more than 300,000 million per second, and ' Suoli evaporation also takes place in solids, but to so slight an extent that we need not consider it here (oomp. p. 279). PHYSICAL ATOMS , 451 the length of the path it travels from one collision to another {the mean free path) is ^^^ part of an inch. The diameter of a molecule, including the sphere of action (there may, of course, be considerable difference in size of the molecules of various compounds depending on their com- plexity) IS 125,000,000 P^i"* of an inch, and their mutual distance from sphere to sphere in a liquid, e.g. water, is calculated to i^^smm P^rt of an inch, i.e. -^ of their diameter, whereas in gas the distance is eighty times greater, or eight times the diameter. In a cubic inch of air there are over 4,000 trillions of molecules, and in what we are pleased to call the vacuum of our best air- pumps there are still nearly 400 billions of molecules in every cubic inch. In this connection we may mention that there are more than 40,000 million cells in a cubic inch of beer, and in order to convert one grain of grape-sugar into half a grain of alcohol, no less than 150,000 millions of cells are required, each composed of a great number of atoms. When we know the size of an atom, it is of course easy to calculate its weight, the specific gravity being known. In the case of hydrogen we find thus that an atom weighs 0-000,000,000,000,000,000,000,004 gramme, i.e. one quadrillion of hydrogen-atoms weighs 4 grammes = 60 grains. When we are airing billions, trillions, or even if.it be only figures not much above what a millionaire may boast, we scarcely realise what we are talking about, and I dare say the above figures have not left much of an imposing impression upon the reader's mind. In order to appre- ciate such figures they must be presented in a way that strikes home, for which purpose we can with advantage use the intuitive principle of instruction, the idea of which is taken from Nature, 1870, p. 553. If we take a drop of water as large as a pea, with a diameter of, say, sixteen millimetres (0-6 inch) and imagine it growing, the molecules also growing proportionally, then when the drop has reached the size of the earth, the molecules would be larger than small shot, but not so large as a cricket ball.' They would, if in stationary position, stand with their surfaces (taking the medium size between small shot and cricket balls) ^rd of an inch apart, filling the whole globe. If this drop of water, grown to the size of the earth, were converted into gas (steam) it would form a globe, the surface of which would touch the moon, the size of the molecules remaining unaltered, the mean free path which the molecules would traverse in -^th. of a second would be about four yards, and their mutual mean distance from centre to centre about two feet. Magnified ten million times, the dimensions might be conveniently measured by millimetres ; ' The distance between molecules in gaseous state (at 0° and at the pressure of one atmosphere) is — ^ mm., measured between their centres. If we imagine 1 mm.^ of gas divided into cubes, the sides of which are equal to this distance, we find the number of molecules in 1 mm.^ gas =2-44 (10)^^. 1 mm.^ of air weighs — ^ m.g.; and if ?ra = the molecular weight (Hj = 2), then one molecule of a gas weighs — i 7:25— ™-6' K 7 is the specific gravity of the molecule relative to water, then the diameter of the molecule = - / — measured in mm. ( — = molecular volume). If we now magnify as proposed, the 10° >f 7 7 3 . — diameter of the molecule will be 56 ,»/ — mm. -v 7 What value has 7 or — ? This is a moot point. Approximately we may make — equal to the molecular volume in 7 7 the solid state. Chemistry ^:eaches that the volume of solids, even at the absolute zero, is not appreciably different from the volume at ordinary temperature. If the molecular volume in the solid state is not known, we must use that of the liquid state ; it makes no difference as regards these calculations. If we forOa make m y = 25, we find the diameter = 164 mm. Na = 31, „ „ = 176 mm. CI2 = 42, „ „ = 195 mm. HjO = 18, „ „ = 147 mm. benzene = 86, „ „ = 247 mm. alcohol = 57, „ „ = 216 mm. (By kindness of Prof. C. M. Guldbebb.) e Q 2 452 ATOMS but the world's wonder of a microscope, which is said to have been exhibited at the World's Fair at Chicago, only magnifies a poor 12,000 times. Besides, if a microscope could be constructed to magnify sufficiently, we should, in order to illuminate the object, require 5,400 times as much light as with our present instruments ; and, what is still more serious, the atom which is such a lively being, moving at a speed of half a mile per second, would first have to be killed, which we have yet to learn how to do. Thus there is, I am afrMd, no hope of our ever indulging in the sight of an atom or a molecule. The motions of the vortices or atoms and molecules are increased by addition, and diminished by reduction, of heat. Both motions, peculiar to vortices, are affected in this way ; but as it is an essential part of the theory of vortices that they shall remain in motion for ever, they cannot, even if cooled to the absolute zero, come to a complete standstill, and incorporate themselves with the surrounding ether ; that would be destruction of matter, all would be ether, and that is in- compatible with the principle of conservation of matter. Besides, although we have not been able to produce the temperature of the absolute zero ( — 273°), and never shall, we have in recent times come pretty close to it, a temperature of — 200° having been produced ; ' but no signs of shadowiness were observed : on the contrary, matter in such extreme cold was more palpable than ever. On the other hand, scientists have proved that chemical action entirely ceases even before so low a temperature is reached. Sulphuric acid, for instance, is perfectly indifferent towards sodium hydrate already at —125° (Gonvpt. Rend. cxv. p. 814). The form of motion which we call affinity between different molecules seems at that temperature to be wholly extinct, but the other form of motion, the affinity between homogeneous molecules and between the atoms of which they are formed, does not appear to be much impaired by the lowest temperatures we can produce. These are the physicists' views on the atoms and molecules, represented, of course, in a popular way, without such learned intricacies of the mathematician as are not within the province of the chemist. His researches go less in the direction of what atoms are than in the study of their chemi- cal properties. Therefore he does not lay so much stress upon the form of the atoms themselves, which to him is a minor question, as on the form of the forces of mutual attraction or repulsion in the different sorts of atoms. We have, with few exceptions, hitherto represented the directions of these foi'ces (affinities or valencies) as lying in the plane of the paper upon which they are represented. . Such representation is, however, not probable. The atoms themselves are certainly not minute pancakes with dimensions in the geometrical plane only ; they are most likely stereometrical bodies with dimensions in space, and though this view was accepted as probable many years ago, its importance and its consequences were not recognised nntil fifteen or twenty years ago, but since then it has been furthered to an astonishing point of development, It is the carbon-atom, almost solely, that has been theorised upon ; a little attention has been given to nitrogen, and scarcely any to the rest ; but carbon is also the most important of all, and many formerly mystic facts have found their ready explanation by Stereometrical Chemistry, or the Theory of the Position of Atoms in Space. ' Air was condensed to a liquid at that temperature at the meeting of the Eoyal Institution, January 20, 1893. CHEMICAL ATOMS 453 POSITION OF ATOMS IN" SPACE We may suppose that the form of the carbon-atom is spherical, and has its four valencies eqnidistantly distributed over its surface, from which each is perpendicularly projected into space. Fig. 1537 If we connect the ends of the valencies by lines we have a regular tetrahedron, in the centre of which lies the carbon-ball, stretching out its valencies to the four vertices of the tetrahedron : Fio. 1538 Instead of representing the carbon-atom as a " ball with four valencies, it will simplify matters to hereafter represent it as a tetrahedron. If two carbon-atoms unite by single linkage they will do so, of course, through a valency of each. These two valencies joining in a straight line will form a common axis of the two tetra- 454 ATOMS hedrons going through the two united vertices, the centre of each carbon-ball, and the centres of the opposite faces of the two tetrahedrons. Fig. 1539 This axis always remains in the straight line of direction if left to itself, and not under the influence of other forces ; but has a certain degree of elasticity, and may be bent when the atoms form a double bond or a closed ring. The atoms, however, move freely round this axis ; in fact, they are supposed to oscillate in- cessantly round it like the balance-wheel in a watch, but immensely quicker. One vertex oscillates opposite to a vertex in the other carbon-atom, the mutual position of the carbon-atoms being determined by the atoms or groups joined to the vertices, so as to bring such groups as have the greatest' affinity opposite to each other (stable compounds). If they are not in this •position (unstable, labile compounds) they are inclined to turn round until the stable position has been found. This is greatly facilitated by increasing the oscillations through the application of heat. The forming of a double bond is effected by two opposite vertices approaching until actual contact. A triple bond is formed from a double bond by another pair of opposite vertices (c) approaching and joining. The following illustrations show the progress and formation of the double and triple bonds between the two above carbon-atoms. Fig. 1541 Fio. 1543 Double bond in process of forming Double bond Triple bond in process of forming from a double bond Triple bond Atoms united by a double bond can oscillate only round the common axis a: b; united by a triple bond they cannot, of course, act independently of each other. If a third carbon-atom joins the two in fig. 1539 it will do so exactly in the same way as the first two united, i.e. by an axis running through one of the vertices and the centre of the respec- tive carbon-balls: Fig. 1544 Three atoms singly linked LINKAGE 455 And likewise a fourth and a fifth ; Fio. 1545 Fig. 1546 Four atoms singly linked Five atoms singly linked It will be observed that a chain built up in this way, as a matter of course, gradually approaches the ring shape ; with the fifth carbon-atom the molecule falls a' little short of a complete ring, whereas a sixth carbon-atom would shoot a little past the first carbon in the ring. Fig. 1547 Six atoms singly linked And with six, or still more so with more than six, carbon-atoms, the chain must of necessity assume, according to circumstances, a left or right screw-form — produced, not by any heThding of the axes, but simply by a slight imrn of each carbon-atom on its connecting axis. Fioi 1548 Fig. 1549 r V Nine atoms singly linked : left-hand screw-formation Nine atoms singly linked ; right-hand screw-formation 456 ATOMS Now we will seewhat shape a chain with double bonds will assume. Suppose the chain consists of doubly-linked carbons only, we will gradually lengthen the chain, commencing with two atoms taken from fig. 1541, but laid down on their sides : Fig. 1550 Fig. 1551 Two atoms doubly linked Three atoms doubly linked (r It Four atoms doubly linked Here no attempt at ring-formation is possible ; however many carbon-atoms we add to the chain, it will remain a perfectly straight one, the alternate axes round which the atoms oscillate being in perpendicular positions to one another, and excluding any bending propensities.' It is different when there is a combination of double and single linkage. If two carbon-atoms are united by a double bond and two others join, one at each end by a single bond, that is to say, by the point of their vertices, and not in a line by the edges, the structure will appear thus: Fig. 1553 One double and two single bonds • A ring-formation, with two double bonds placed as in fig. 1551, has been suggested for some compounds; for instance, sylvestrene (comp. terpenes, p. 50) has been represented by one of the following figures {Ber. xxi. p. 172) : Fig. 1552 a Fio. 1552 b but this seems quite incompatible with the tetrahedron theory, as an addition of three more carbon-atoms to one of the free valencies of fig. 1551 would have no tendency to meet any of the others, because of the four different directions in which they all point. ^ LINKAGE 457 A ring-shape is obviously in formation ; we will add another carbon at each end by double bonds : Fia. 1554 A double and a single bond alternately Thus we see that six carbon-atoms united in this way are close upon forming a complete ring. When two carbon-atoms are united by triple bond, only one valency in each is left free to combine with other atoms; therefore anything added must be bound by a single bond. The structure of two such pairs will then be this : Fia. 1555 They have both one common axis ; no matter how many links of the same sort we may put together, the chain will not deviate from the straight line. Even if we construct a chain from a single pair of trebly bound carbon-atoms to begin with, continuing with a structure of single bonds, or mixed single and double bonds, the ring formed will not include the triple bond, because the ring-shape thus formed would be too small to give room for it. Therefore no closed ring is known to contain a triple bond. This sort of linking will be seen from the illustration : Fia. 1556 It is easy now to understand how and why closed chains are formed, and also the reason for the frequent occurrence of pentagons and hexagons, and why 7- and S-hydroxy-acids form lactones, but not a- and /3-compounds. The rings are almost ready-made beforehand, and all that is required is a free valency at each end ; they will unite through the attracting force between free valencies, and thus complete the ring. When this force is strong enough, it will draw together, though 458 ATOMS probably with some difficulty, the ends of a bit of chain of three singly linked carbon-atoms, not- withstanding the distance is relatively great ; the ring of four such atoms is more easily formed, but the easiest of all are, of course, chains of five or six atoms, because of the ring being all but formed. Even seven will close up, as we have seen with hepta-methylene's derivatives ; but from their rare occurrence we may conclude that it is not easily done. The reason for this is probably that the last carbon, with its free valency, is too far away from the other free valency, and its force perhaps lessened by the proximity of the atoms alongside which it runs in screw-fashion. A ring of eight or more successive carbon-atoms seems impossible of formation, though even decagons have been formed by interposing links of other elements, principally nitrogen. The closing of rings may be thus illustrated : Fia. 1557 Fia. 1557 a Three singly linked carbon-atoms Closiag of three singly linked atomg Fig. 1558 ,Fia. 1558 a Four singly linked oarbon-atoms Closing of four singly linked atoms Fig. 1559 Fig. 1559 a Five singly linked oarbon-atoms Closing of five singly linked atoms LINKAGE 459 Fio. 1560 Fio. 1560 a Six singly linked carbon-atoma Closing of six singly linked atoms Fio. 1561 Fig. 1561a Six alternately singly and doubly linked carbon-atoms Closing of six alternately singly and doubly linked atoms We have hitherto made use of carbon-atoms as if their valencies were free, those of course excepted by which they are tied together. We will now see how they behave when all their valencies are engaged in the same, or in different ways. We will illustrate two carbon-atoms united by single bond, and six hydrogen-atoms attached to their free valencies, using for hydrogens the same signs as before : Fio. 1562 Ethane The two carbon-atoms, it will be remembered, are revoluble round their common axis; and can therefore be turned into three different positions, a new vertex each time facing one of the vertices in the other carbon-atom. It will, however, be seen that, in whichever of the three positions we place the two carbon-atoms in the above figure, it makes no difference in the compound regarded as a whole : in all three cases a hydrogen-vertex in one carbon-atom faces a hydrogen-vertex in the other. 460 ATOMS We will now introduce a new element to wtich hydrogen lias a very strong affinity, viz. chlorine. The three positions created by turning one of the carbon-atoms round are here represented. Fig. 1563 Fig. 1564 Fig. 1565 Neither in this case do the various positions make any difference ; in all of them a chlorine faces a hydrogen-atom, and the other hydrogen-atoms face each other in pairs. If we now introduce a chlorine-atom in the lower carbon, too, the three possible positions would be these : Fig. 1566 Fig. 1567 Fig. 1568 In the first figure chlorine has taken possession of a vertex in the lower carbon-atom facing the chlorine in the upper atom. But chlorine has too much affinity to hydrogen to remain there; it will try to get as near one of the hydrogen-atoms as possible, and will therefore move the carbon round its axis until it has arrived opposite a hydrogen. It can do this by turning either to the right or to the left. In the second figure the upper carbon-atom has been turned to the left, in the third to the right. In these positions there is stability. The two figures bear to each other the same relation as a right-hand to a left-hand glove (enanthiomorphisni), otherwise they are identical, and their chemical properties are exactly the same ; in fact, the existence of these two compounds with such difference is solely based upon theory, and supported by no direct fact. In more compli- cated compounds we shall see the difference indicated by their physical properties. If the attractive power between the different atoms or groups fixed to one Carbon-atom and those placed on the other is not particularly strong, all three positions may be possible ; but generally one position seems to be preferred to the others, and is termed the favoured position, in which the compound shows itself more stable than in the others, and into which it arranges itself at the first opportunity. It will now be understood what perhaps has been rather puzzling to the reader, that it is of no consequence in what order the atoms or groups are placed upon the same carbon-atom (vide p. 8), provided no favoured position comes into play. They do not, in point of fact, leave their positions ; it is the carbon-atom that turns round upon its axis. Further, we can now better understand also the nature of double and triple bonds. The common axis between two carbon-atoms is supposed STBRBO-GHBMISTRY 461 to possess a certain degree of elasticity, like a steel spring ; in order to bend two atoms so that two opposite vertices come in actual contact (vide fig. 1539 &c., p. 454) some force is required that will overcome the spring-resistance of the axis. In the earlier part of this treatise we have freely spoken of the removal of two hydrogen-atoms as if it were the easiest thing in the world. That is, however, theory only ; we cannot go about picking hydrogens like we do apples and pears from our fruit-trees ; in chemical practice we have to resort to devices and to the use of two forces, either affinity or heat, both being most probably but two forms of the same force, motion. We use affinity by placing, on two opposite vertices, bodies that have a great liking for each other, e.g. chlorine and hydrogen (as in figs. 1563, 1564, and 1565), which together form hydrochloric acid. If we then approach a new body which has a great affinity to hydrochloric acid, e.g. an alkali, that force is so strong as to overcome the elastic resistance of the axis, and make the two carbon- atoms bend towards each other until chlorine and hydrogen come into actual contact and can form hydrochloric acid ; but at the same time the vertices of the carbon-atoms also come in contact, and, being left by their chlorine- and hydrogen-appendages, the two free valencies have sufficient affinity to resist the tendency of the elastic axis to raise itself again. There is thus a certain degree of tension in the situation, and on very slight provocation — the approach of two chlorine-atoms, for instance — the connection between the two vertices will snap, and the two carbon-atoms spring back into their original upright position. Therefore double bonds cannot be so strong, as single bonds. If two chlorine-atoms are affixed to the vertices (as shown in fig. 1567 or 1568), it is evident that two faces and not only two edges of the carbon-atoms may close up, and the triple bond be formed. As heat is but another form of motion, it might perhaps at a first glance seem improbable that a less powerful binding should be effected by such means. Still, we know that double and triple bonds are frequently formed through the application of heat. Our theory readily explains that. The atoms are not supposed to be in a state of static rest in their mutual positions, as frequently mentioned ; on the contrary, they are oscillating round the connecting axis. When heat is applied, these oscillations become more and more impetuous, and, as a consequence of the centrifugal force, the path of the upper carbon's vibrations will become more and more depressed, whilst that of the lower carbon will rise, as when a ball fastened to a string is whirled round. At last the oscillation- path of the two carbon-atoms will become identical ; that is to say, two of their edges will come into contact, and through their affinity the force by which any appendages are held by the vertices is lessened so much that these appendages are flung off and the double bond established, after which the oscillations take place round the axis a : i (fig. 1541, p. 454). By increased appli- cation of heat these oscillations become in turn also so violent that at last the vertices c : c meet, and the triple bond is formed. With this tlieory as the base, stereo-isomerism, which we have had occasion to observe so many times, may be easily explained. We will as a first example take ethylidene lactic acid, which has been found to exist in three optically different forms. It is composed of three carbon-atoms, one of them having three hydrogen- atoms attached, another a hydroxyl and a hydrogen, and the third is carboxyl. Our usual repre- sentation of the compound is this (vide fig. 692, p. 179) : Fig. 1569 462 ATOMS Eepresented by the stereometrical tetrahedrons, the compound may be illustrated by fig. 1570. It will be noticed that the intermediate carbon-atom has, at one of the top vertices, a hydrogen- atom attached, and at the other a hydroxyl. The mass of the latter is greater than that of the former, wherefore the carbon-atom by the oscillations is thrown slightly out of equilibrium,' which will be better observed if we look at it from the side, as shown by figs. 1572, 1573. Pig. 1570 Fia. 1571 Fig. 1572 Fig. 1573 ' Ethylidene-lactic acid Propionic acid Active ethylidene-lactic acid ; dextro-rotatory Leevo-lactic acid ; Isevo-rotatory The figure 1571 is propionic acid, which we have before (fig. 669, p. 176) represented thus: Pig. 1574 o The intermediate carbon-atom in this compound has a hydrogen-atom on each side, is therefore evenly balanced, and its structure forming part of a ring will cause the molecule to dart through the ether withftut any rotative movement. ' I am not prepared to prove this assertion, because — even if nothing else were amiss— our imperfect knowledge of the real nature of the force we call affinity makes it impossible to argue the point mathematically. The facts, however, which I am going to submit in the following pages agree so well with the assertion as to make its correctness, in my opinion, highly probable, further supported, as I think it is, by the following considerations : I am unable to find that any optically active compound has been discovered in which the asymmetrical carbon forms an end-link of the chain ; thus no active compound with either one or two carbon-a,toms has hitherto been found amongst methane- and ethane-derivatives, though such compounds with an asymmetrical carbon, of coarse as end-link, do exist, e^g. ohloro-brom-acetio acid (Beilst, i. p. 452 ; B. dt 8. i. p. 544). Activity is found in derivatives of the higher homologues only, commencing with propane, and in these the asymmetrical carbon-atom is always — as far as they have been investigated — an intermediate one bound on two or more sides by other carbon-atoms, never an end-link. Now, the oscillations of an intermediate carbon atom must evidently be different from those of an end-carbon, because the latter are formed from one motion only, while the former must be the resultant motion of two or more oscillations which such a carbon-atom performs in harmony vyith those of the carbon-atoms to which it is joined, being kept by the force or forces (which in the absence of a more definite knowledge of their nature I will call the centrifugal force) in a distinct position dependent on such factors as centres of gravity or inertia, moments of inertia or forces, &a. ; it is impossible at present to formulate the law according to which these factors would act, but probably it will be to the effect that ' atoms are formed into groups in which the moment of inertia round the axis of rotation is the smallest possible,' or something like it. When those factors are altered from a centric to an eccentric influence, as they are by the unequal loading of an asymmetrical carbon, the connecting axes would — if the side-carbons remained in their positions — be subjected to a strain, which, if not entirely removed, must, at least, be considerably lessened by the asymmetrical carbon turning round on one of the axes and carrying the other carbon-atom with it into the new position ; an arrangement that it consequently prefers, as asserted above. The oscillations and their influence upon atoms and molecules are still enveloped in mystery, and we should not be surprised to learn some day that they are to the molecules what the movements of cilia are to the lower animals — their propelling force. AU this belongs to the future chemistry, the kinetic theories, into which I shall not, for excellent reasons of my own, go any further. SOREW-THEOEY 463 But when a hydroxy], instead of one of the hydrogen-atoms, is planted upon this carbon-atom, the balance is disturbed, and the carbon-atom thrown over to one side by the centrifugal force of the oscillating movement. It can do this by a turn on one of the axes by which it is connected with the two other carbons ; but in doing so it will have to carry with it the carbon-atom to which it is bound by the other axis, transforming thereby the ring form into that of a screw, and the molecule, now rushing through the ether, must assume a rotatory motion. The form of the screw will depend upon the side to which the hydroxyl is attached; fig. 1672 represents a right-hand screw, which, re- volving many hundred thousand times per second, will throw the plane of the polarised light that enters one end of the screw over to the left hand of the spectator at the other end. In the same manner the light will be thrown over to the right from the structure (fig. 1573), which forms part of a worm of a left-hand screw. If these two structures be present in equal numbers, the light will be thrown just as much to the right as to the left ; in other words, there would be no deviation of its propagation from the original plane. Such compounds are termed inactive isomers. It will be noticed that the two carbon-atoms on each side of the intermediate one are differently engaged, one being a methyl (OH3), the other a carboxyl (OHOj). The intermediate carbon-atom is thus differently engaged on all four valencies by (1) a hydrogen-atom, (2) a hydroxyl, (3) a methyl, and (4) a carboxyl. It is therefore termed an asymmetrioal ca/rbon-atom, and in all compounds which cause the rotation of light, such an asymmetrical carbon-atom is said to be always present (though I doubt the correctness of this assertion, vide p. 467 seq.). The essential thing is not the two side attachments only : in the above case the hydrogen and the hydroxyl, though the difference in their mass (and perhaps also in their interatomic distance') is no doubt primus motor; but a difference in the combinations of the two other valencies is just as necessary, because, being of unequal mass, the one with the greatest would probably remain stationary, and the one with least mass would be carried into a new slanting position with the asymmetrical carbon-atom,^ whereas when of equal mass both would change position simultaneously with the asymmetrical carbon, and therefore the relative position of all three would undergo no change. With the symbols adopted iu the foregoing part for representing structures pictorially, the optical differences of the two lactic acids might have been indicated in this way : Fig. 1576 -#—0 Dextro-laetio acid LiBvo-lactie acid But, as explained before, comparability and conspicuity would suffer, and therefore, apart from the fact that the exact position of the hydroxyl is known in comparatively few compounds, this distinction has been omitted, except in one or two cases ; for instance, in some structures of the sugars. When two asymmetrical carbon-atoms are present in a compound, four different isomers are admitted by the theory, and facts have confirmed the theory. ' Vide Guye, ^tude sur la dissymitrie moUculaire, G6n4ve, 1891. ' In the figures I have let the oarboxyl-group follow the movement of the asymmetrioal carbon, and left the methyl stationary instead of reversing the process. This has been done on account of the difBculty of representing the correct position in drawing without leaving out of sight essential points that would be hidden behind the atoms nearer to view. 464 ATOMS Such a compound with two asymmetrical carbon-atoms is tartaric acid, represented by our system (fig. 731, p. 187) thus: Pio. 1577 — #— O Tartaric acid Represented by tetrahedrons, and seen from the same point of view as the lactic acids just mentioned, the different isomers may be illustrated in this way : Fio. 1578 Fm. 1579 Fig. 1580 Pm. 1581 Succinic acid fig. 714, p. 185) Dextro-tartaric acid Ljevo-tartaric acid Meso-tartaric acid The first of these figures is succinic acid, from which the different tartaric acids are formed by substituting hydroxyls for the two top carbon-atoms' hydrogens. It will be seen that these two carbon-atoms in succinic acid are in a state of equilibrium, being evenly loaded on both sides with hydrogens; but if we, on each of them, replace a hydrogen by hydroxyl, as in fig. 1579, the two front carbons will incline to the left, and the two rear carbons to the right, evidently forming part of a right-hand screw, which, darting through the ether, will probably assume a rotatory motion, and undoubtedly influence the plane of the polarised light passing through it, giving it a turn to the left of the observer. In fig. 1580 the positions are reversed; consequently the molecule will assume the form of a left-hand screw, throwing the light over to the right. In fig.' 1581 both hydroxyls have taken up positions on the same side of the molecule ; consequently both pairs of carbon-atoms are thrown over to the same side ; their positions relative to each other are not altered ; they remain the same as in succinic acid, forming a ring and not a screw ; the mole- cules rush about without any rotatory motion, and the polarised rays pass unaffected through them, i.e. it is an inactive form of isomerism. This figure may also be regarded as composed of the two front carbons of fig. 1579 and the two rear carbons of fig. 1580, and is, therefore, generally described as consisting of half a molecule of dextro- and half of leevo-tartaric acid ; but, of course, it is succinic acid in which the hydroxyls have replaced hydrogens on the same side of the molecule. Another inactive tartaric acid, the fourth isomer, is a mixture of equal parts of wliole molecules of dextro- and Igevo-tartaric acids, and termed racemic acid, as mentioned, p. 188. Such mixture can by crystallisation be mechanically separated into its components, the crystals of one acid being the reflected image of the other— exactly like the two molecules, figs. 1579 and 1580, SCREW-THEORY 465 which is not the case with the inactive form represented by fig. 1581. Illustrated by our pictorial symbols, the different isomers of tartaric acid might— more correctly than on p. 187— be represented tlms : ^ Pig. 1582 Fia. 1583 Dextro-tartario acid Lsevo-tartario acid Fin. 1584 Meso-tai'taric acid It should be stated here that the above explanation of optical activity has not received the sanction of authorities — at least not yet — for the reason, amongst others, perhaps, that the theory has not been propounded before, that I am aware of ; ' I may therefore be allowed to support the idea by some more reasons for its probability, though not a proper subject for the purpose of this treatise. Before proceeding, however, it is necessary to explain that the figure (1578) of succinic acid is under no circumstance quite correct, because it represents an unstable structure of the molecule, the two carboxyl-hydroxyls (one is behind the foremost carboxyl, and therefore not visible) being in close proximity, although under the attraction of hydrogens near by. It represents, however, the position of the atoms at the moment of the acid's formation into anhydride ; a more correct representation would be Fio. 1585 because here the hydroxyls would be facing hydrogens, besides being themselves farther apart, and thereby creating stability in the structure. But this position of the hydroxyls would greatly ' The theory is strictly a physical, and further, development of Guye's mathematical deductions {I.e. p. 463) with which it is in perfect accord. H H 466 ATOMS impair the lucidity of the other figures, even if in the formation of tartaric acid from succinic acid they stuck to their places, which they do not do, because the carboxyl must turn round its axis to find a stable position, according to which side of the molecule the alcoholic hydroxyls are afiixed to. I have therefore preferred giving the carboxyls the unstable, but more neutral posi- tion ; the more so as it is not of consequence to the further development of the theory. But even with such corrections the structure given above to succinic acid is not an interpretation of the views of our greatest authorities on this subject (Wislicenus Baumliche Anordnung der Atome, Leipzig, 1889). I have deemed it sufiBcient for the stability of the structure to make the carboxyl's hydroxyls each face a hydrogen, at the same time removing them from each other by turning the carbon-atom round its axis ; but accordiag to the said authorities the proximity of the carboxyls themselves, in their entirety, causes the instability of the structure, and, in order to avoid this proximity, one of the two cwrbon^atoms to which the carboxyls a/re affxed makes a turn round their common axis, carrying with it the carboxyl, and placing it in the position represented in the follow- ing figure : Fig. 1586 \ y ■1 Succinic acid If this be the correct structure then succinic acid has already the screw-form, and the theory advanced above must be abandoned, whether we assume that the unequal loading of the two inter- mediate carbon-atoms by hydroxyls influences their mutual positions or not. In the latter case all the structures, whether optically active or not, will have screw-formation ; in the former case the structures will have to be represented thus : Fig. 1587 Fig. 1588 The angle to which the two atom-complexes will be inclined by the weight, or mass, of the hydroxyls cannot exceed that given in the figures without endangering the stability of the structure by the mutual approach of two hydroxyls ; indeed, this very danger was the reason why the structure of succinic acid in fig. 1586 was adopted. We may therefore assume that the above representations SORBW-THEORY 467 are correct, provided tlie structure of succinic acid (fig. 1586) is correct, and we see then that one of the optically active tartaric acids has decidedly no screw-formation. Of course, it would, therefore, be fatal to the dependence of optical activity on screw-formation if fig. 1686 were a correct representation of the structure of succinic acid ; but I do not see the necessity of accepting it as such : it seems to me not even probable. There is no reason for assuming the existence of any repelling force between the two carboxyls that should necessitate such extreme measures as turning round a whole complex of two carbon-atoms ; on the contrary, they are always very willing to unite by dropping a molecule of water when the necessary energy is provided ; on the other hand, the electro-positive hydrogen has attractions after which the electro-negative hydroxyl is always running. In fig. 1578 the two hydroxyls (one of which is hidden behind the front carbon) are in a position in which they have to choose what to do ; either combine, dropping a molecule of water, or turn the carbon-atom a little round its axis in order to take up the position opposite one of the hydrogens ; they choose the latter expedient for several reasons ; partly because the formation of water requires more energy than they are possessed of, whereas, probably, none is required for turning the carbon-atom; partly because the attraction between hydroxyl and hydrogen, under the circumstances, is greater than between the two hydroxyls; and finally, because the law of preservation, perhaps, exists for a molecule's structure as well as for matter generally, wherefore it prefers an arrangement in which its structure is as little disturbed as possible. It is natural that it should choose an arrange- ment by which the greatest stability is insured, and therefore the two hydroxyls go one to the right and the other to the left, as indicated in fig. 1585, instead of both to the same side, by which the instability on account of the proximity of the hydroxyls would continue to exist, only in a lesser degree. For these reasons I feel inclined to consider the structure of succinic acid more correctly represented by fig. 1585 than by fig. 1586, and the screw-theory unimpeachable from that side. At first sight it may perhaps be objected to the theory that the eifect of the rotatory movement of the molecules upon the plane of polarised light will be neutralised by the fact that they move forwards and backwards, and that the number of one sort must equal that of the other ; it should, however, be remembered that the light is also moving and only in one direction ; consequently it would transverse many more of one sort by meeting those returning than of the other, by over- taking those travelling the same way as the rays. In order to carry the theory out also in closed chains with an asymmetrical carbon-atom in the ring, it becomes necessary to assume a certain degree of elasticity in the bonds connecting the carbon-atoms, sufficient for a screw-like formation of the ring ; when we see how much the chemical properties of compounds are alike, if their only structural difierence is a breakage of the closed chain, the assumption of such an elasticity seems justifiable, as exemplified further on (vide fig. 1588 e). Since Pasteur, in the year 1848, separated racemic acid into dextro- and laevo-tartaric acids, and amongst other possible causes of their optical differences suggested, in a general way, a screw-formed arrangement of the molecules, several other scientists have tried to solve the difficulty in difierent ways, some of them utilising Pasteur's idea. These attempts at explaining the optical properties, though in most cases very ingenious, do not seem to have gained general approval, perhaps just because they have been too ingenious, and science, for want of an acceptable explanation or theory, has had to content itself with the following postulate dating from stereo-chemistry's earliest days : Every actiue compound has an asym/metrical carbon-atom, hut not every compound with an asijmmetrical carbon-atom is optically active. The latter part of the postulate has since then been questioned, because chemists have in a great many cases succeeded in separating such compounds as were formerly considered inactive, mostly in the same way as Pasteur produced the components of racemic acid through the activity of living organisms (Penicillum glaucum). This success has caused many chemists to abandon the latter part of the postulate, and to prognosticate the separation of all com- pounds with an asymmetrical carbon-atom into two compounds with opposite optical properties, even such as consist of the asymmetrical carbon-atom only, e.g. chloro-bromo-iodo-methane, OHOlBrI (^Stereochemie von Dr. 0. A. Bischoff, 1893). The above rule applies only to compounds in which but one asymmetrical carbon-atom is present; when there are more the rule is modified, the modifications being almost as numerous as H n 2 468 ATOMS the contingencies ; but even thus, difficulties are met with which have not been explained away in a satisfactory manner ; for instance, asparagine (fig. 1179, p. 329) is a compound with only one asymmetrical carbon-atom, and we are prepared to find, in analogy to the lactic acids, three optically different asparagines ; three have actually been found, two active and one inactive ; and it should consequently be possible to prepare the latter by mixing the two former in equal quantities ; but in point of fact it cannot be produced in this way (Ber. xix. p. 1694), and a structiJre different from that of the active form has therefore been suggested (fig. 1179, A and B, p. 329), without, however,, supplying an explanation of its inactivity. Farther there are compounds without any asymmetrical carbon-atom, e.g. some terpenes and glycerides, which undoubtedly are possessed of optical activity j a fact of which no explanation has been attempted — I have not found the latter even mentioned in treatises on the dependence of optical activity on an asymmetrical carbon. Again, there are active compounds whose derivatives are less active, sometimes indeed inactive, or even with reversed activity, all of which we have to accept as facts for which the asymmetrical carbon offers no explanation. The screw-theory, it seems to me, explains these anomalies in an extremely simple, natural, and unconstrained way. The asymmetrical carbon, which in the postulate is all important, plays in this theory but a secondary part, and is only of moment as the agent through which a molecule is caused to assume a screw-form ; everything depends on the screw-form, and the form of the screw depends upon the radicals attached to the carbon-atoms, what they are and where they are attached, We vdll take tartaric acid as an example. We have seen that it is composed of four carbon-atoms, two of which constitute asymmetrical carbons, and the other two carboxyls. Let us, for the sake of brevity, call the side-appendages to the former, wings, and the latter the tails. In this case one of the wings in each pair is hydroxyl, and the two carbon systems, of which tartaric acid consists, is thereby caused to incline in different directions, the two forming an angle, deter- mining the pitch of the screw, and through it the rate of velocity with which it will rotate. If,, instead of hydroxyls, the wings are represented by radicals of greater mass, the angle, or in other- words the pitch, will be increased ; and, assuming that the speed with which a molecule travels is not thereby sensibly affected, its rotation will decrease in proportion as its pitch increases. If additions to the mass of such radicals are constantly made, a point will soon be reached when the helix is stretched out to a straight line, the molecule losing the form of a screw ; by continued additions a screw of the reversed worm will begin to form, with constantly decreasing pitch and increasing speed of revolutions. If, on the other hand, we increase the mass of the tail by similar appendages, the angle between the two carbon systems will be reduced, the pitch decreased, and the rotation increased. Thus, by adding either to the wings or to the tail, or to both, the movements of a molecule and its consequent power of turning the polarised plane can be regulated at will, increased, decreased, stopped, or reversed. The action is well illustrated by a piece of cord : if while kept taut it is untwisted the strands will foi'm straight lines, and continued motion will twist them, in Bcrew-form, in the opposite direction to that they previously had. The -diagrams explain it easily : Fig. 1588 A Fig. 1588 e Tartaric acid SOREW-THEORY 469 Fia. 1588 c Fia. 1588 D 9 9 6 O Di-acetyl-tartarie acirj Di-aoetyl-tartaric-ethyl-ether Pig. 1588 A is tartaric acid, from wtich. we form di-acetyl-tartaric acid by substituting acetyls for the alcoholic hydroxyls, representing the wings of the two carbon systems, the divergency of which is consequently so much increased that the helix of the original positive screw-form is not only stretched out into a straight line (inactivity), as represented in fig. 1588 B, but has passed. into the reversed negative screw-form seen in fig. 1588 c. If we now attach radicals to the tails (carboxyls) of di-acetyl-tartaric acid the effect of the wings will be counteracted, and a re-formation into the original positive screw commenced ; thus, if di-acetyl-tartaric acid is converted into its compound ether by attaching methyl to the tail, the negative turning power of the compound is considerably lessened, yet still negative ; but if ethyl- ether is formed the structure will be nearly that represented by fig. 1588 D ; that is to say, the helix will have just passed the straight line (inactive form) and formed a positive screw of very high pitch and small turning power. If iso-butyl is employed as substitute in the tail the effect of the acetyl substitution in the wings is almost counterbalanced, the di-acetyl-tartaric iso-butyl-ether , having nearly the same optical activity as tartaric acid itself. If, instead of acetyl in di-acetyl-tartaric acid, we employ, as wings, a radical of still greater mass, e.g. benzoyl, the effect is further increased, the di-benzoyl-tartaric acid turning the polarised light far more to the left than the corresponding acetyl compound. Again, if we leave the wings of tartaric acid undisturbed, and make additions to the tails only, the pitch of the screw is decreased, the rotation and consequent power of turning the polarised plane are increased, according to the mass of such additions. The following tables, taken from Stereochemie nach J. H. Van't Hoff's Bix Annies dans I'histoire d'une theorie bearheitet von Dr. W. Meyerhoffer, 1892, seem to strengthen the screw-theory : aDat20° Tartaric methyl-ether „ ethyl- „ „ propyl- „ „ iso-butyl-„ Di-acetyl-tartaric acid methyl-ether ethyl- „ . propyl- „ . iso-butyl-„ . + 2-14 + 7-16 + 12-44 + 19-87 23-14 — 14-29 + 1-02 + 6-52 -1- 10-29 4^70 ATOMS Di-benzoyl-tartaric acid ....... — 117'68. „ „ methyl-etlier .....— 88-78 „ ethyl- „ - 60-02 iso-butyl-„ - 41-95 Just as easily may the optical behaviour of asparagine be explained. Here, only one asym- metrical carbon is present, the wings of which are the same, H and NHj, in both the active and inactive forms {vide figs. 1179, a and B, p. 329) ; but the tails are essentially different. In the active form, fig. 1179 a, the heavier tail (OH^OONHj, atomic weight =58) is to the, right of the asymmetrical carbon, the lighter tail (COOH=45) is to the left. In the inactive form the heavier tail (OH2COOH = 59) is to the left, the lighter (C0NI[2= 44) to the right; consequently the left one will in the active form follow the inclining movement of the asymmetrical carbon, while in the inactive form it would under ordinary circumstances be the right tail. The circumstances are, how- ever, not ordinary in the case of asparagine ; the stationary tail of inactive asparagine consists of the carboxylic radical of acetic acid, a strongly electro-negative body, whilst the movable tail finishes in an amido-group, a strongly electro-positive body, the negative effect of the neighbouring carbonyl being neutralised by the amido-group of the asymmetrical carbon. In the stereometrical con- figuration the two tails come into close proximity, and their affinity will resist the effort of the asymmetrical carbon to separate them ; the molecule will consequently retain its ring-form without any rotatory property. In the active form of asparagine the arrangement of the electro-positive and negative groups is entirely altered ; the asymmetrical carbon has here gone over to the carboxyl tail, the positive amido-group almost neutralising the negative character of the now movable lefb tail, whilst the basic property of the other, now stationary, right tail is greatly impaired by the neighbouring carbonyl, which is no longer influenced by the proximity of the asymmetrical carbon's amido-group. The affinity between the two tails is therefore not sufiBcient to resist the effect of the unevenly balanced asymmetrical carbon, and the molecule will assume the screw-form, and with it optical activity. In asparagine the screw-formation was prevented by the force binding the two tails together, but we have instances of optical inactivity that may be explained by the same force preventing the inclining movement of the asymmetrical carbon by binding the wings together. Thus some diversity of opinion has reigned as to the influence which substitution of halogens for hydroxyls exercises upon certain compounds. Some chemists have obtained from malic acid an active, others an inactive, form of mouo-chloro-succinic acid (Ber. xxvi. p. 210). If we look at succinic acid, fig. 1578, p. 464, or malic acid, fig. 1591, p. 469, we shall see that a chlorine atom, substituting one of the hydrogen wings of the former or the (alcoholic) hydroxyl wing of the latter, will face a hydrogen representing an opposite wing. The two may have sufficient affinity to resist the force that would otherwise throw them out of balance, and the molecule will become inactive ; but if through another mode of preparation- — for instance, in a higher temperature — the chlorine atom is moved away from the hydrogen's sphere of action the centrifugal force comes into full play upon the unevenly balanced carbon-atom, and will sustain the molecule in the resulting screw-form and consequent activity. It follows from this theory, as a matter of course, that difference in atomic weights of the groups round an asymmetrical carbon is not absolutely necessary for optical activity ; in the case of equality all depends upon the configuration ; a group whose mass is spread out in an elongated form will affect the movements of a molecule in a way other than when the mass is concentrated round a point. In fact, Guye has experimentally proved that, e.g. ethyl, 03115 = 29, and formyl, OOH = 29, are consistent with optical activity. Optical inactivity of compounds without any asymmetrical carbon-atom has been an article of belief considered so incontestable that structures have had to conform themselves to the theory, not the theory to structure. A. v. Baeyer has, however, recently {Ber. xxvii. p. 450) with irrefutable stringency proved that, unless the whole tetrahedron-theory is mere fiction, di-pentene (vide ter- penes, p. 50) cannot have any asymmetrical carbon-atom in its structure ; but di-pentene is simply SOREW-THEORY 471 Fia. 1588 E Di-pentene Pig. 1588 f a mixture of the two active compounds, dextro- and l^vo-liraonene ; neither, therefore, can the latter have such a carbon-atom in their structures. One such case is suflBcient to shake the asym- metrical postulate to its very foundation and make us look for something nearer the truth. The screw-theory seems to me capable of taking up the mission. An atom has admittedly a sphere of action, or, in other words, there must be a certain elasticity in the force binding one atom to another so that they can, to a certain extent, be removed from each other without the bond breaking. When we now look at the structure of di-pentene as demonstrated by A. v. Baeyer we see the line a b dividing it into halves, and if the elasticity of the bond at a allows the lower half to turn horizontally to the right or left on the point of contact between the bonds at b, a right- or left-hand screw is evidently formed, and with it are the necessary requirements for optical activity created. It now only remains to see if a plausible cause can be adduced explaining a strain upon the bond a, sufficient to make one of the halves turn on the pivot at b. I think the unsymmetrical configuration of the iso-propyl-group, in conjunction with its greater mass as compared to the methyl on the top-half of the molecule, quite sufficiently accounts for the formation of a screw when we remember that according to the tetrahedron theory the position of two of iso-propyl's carbon-atoms must be outside the plane of the hexagon, and must be kept there by the oscillating movements of the atoms ; a position that has not found a true representation in the above illustration. This view receives some support in the fact that optical activity ceases when the double bond A^ shifts- to A*'® (comp. p. 50), that is to say, when di-pentene is converted into terpinolene (fig. 1588 f), the structure of which A. v. Baeyer has determined with the same exactitude as that of di-pentene ; on account of the double bond by which the iso-propyl group is now bound to the hexagon, the formerly unsymmetrical position of its two carbon-atoms are, in accordance with the tetrahedron-theory, converted into perfectly symmetrical positions in the plane of the hexagon, as represented in the figure. The optical activity of compounds consisting of a long chain without any asym- metrical carbon has been very little inquired into. According to the screw-theory all compounds of more than five or six such carbon atoms assume by necessity the screw-fprm (vide figs. 1548 and 1549, p. 455), unless they assume a possible, but perhaps not probable, zig-zag form ; some glycerides have been found optically active, but only further investigations can confirm or con- tradict the theory. The theory is so full of consequences that its invalidity if quite incorrect must soon manifest itself, though it may perhaps take a long time to make it acceptable if it be a step in the right direction. I shall only, as an example, mention one or two of these consequences. We have seen that tartaric acid is composed of two exactly similar groups, and that therefore an inactive acid is produced by placing both hydroxy Is on the same side of the molecule, no matter whether on the right or left side ; but there are many compounds in which the two groups are not similar; if the hydroxyls are placed on the same side of such compounds the two groups will incline, but not to the same degree, the one with a lighter tail inclining more than tliat with a heavier. Also in such case the structure represents a screw, but with a smaller pitch, and conse- quently optically more active than when the hydroxyls are placed on each side of the molecule. Two sorts of such screws with smaller pitch may, according to the theory, be formed — one as a right- the other as a left-hand screw, besides the two in which the hydroxyls are placed on different sides of the molecule. Where screw-formation is impossible, optical activity is excluded ; an asymmetrical carbon-atom that has not on two opposite sides other carbon-atoms cannot form a screw, therefore an inactive compound like chloro-bromo-iodo-methane (hypothetical ?), mentioned p. 467, will always remain inactive, and cannot be split into two compounds with optically opposite properties, as asserted by the asymmetrical carbon postulate; nor can compounds like ethyl- or propyl-nitrolic acid {vide fig. 1085, p. 305) ever turn active, in spite of their asymmetrical carbon (provided, of course, the Terpinolene 472 ATOMS structure is correct as there represented, and supposing nitrogen does not possess the same capa- bility of forming screws as carbon), because they have not this qaalification necessary for screw- formation. The screw-theory, if correct, may also assist us to a more exact knowledge of the arrangement of groups round an asymmetrical carbon. The structure of active amyl-alcohol, for instance, may be illustrated in three different ways, according as it pleases us to arraage the various groups. Fig. 1588 q Fig. 1588 h ( — ( ( — © p 1 p ( 1 O ( ) < 1 Fio. 15881 9 0—{t-~0 Q — §►- But, of course, only one of them can represent the actual structure. Now, we know that Itevo- amyl-alcohol turns the polarised light a little to the left (a D = — 5'7) ; but if we replace the hydroxyl by chlorine, the chlor-amyl thus formed will turn it to the right (a D = + 1-24) ; if by bromine, it will be turned a little more (aD=+3'5); a ad if by iodine, still more (a.D=+5'4'l). This is in full analogy to the behaviour of tartaric acid, as explained above, and therefrom we conclude that these substitutions take place in the wings of the asymmetrical carbon. Further, we know, as just stated, that a screw can only be formed from the horizontal rows of carbon-atoms of the above structures, because the asymmetrical carbons have not carbon-atoms on both sides in the perpendicular rows. Now the first structure, fig. 1588 G, is the only one in which hydroxyl is placed in one of the wings ; consequently that must represent the correct arrangement of the various groups round the asym- metrical carbon ; possibly the other amyl-alcohols also exist, but their optical behaviour must differ from the above. I have stated above that the idea of a screw-formation as the cause of the optical properties of a large number of organic compounds is not at all a new one, but the idea has not been developed into a theory sufficiently simple and natural to be acceptable to the majority of chemists, and has, therefore, so far as I am aware, remained, like the asymmetrical carbon, a mere postulate. The simpleness of the theory here submitted ought to be its commendation ; at the same time this very simpleness and the fact that such an idea should not have presented itself to some- body else long ago make me hesitate and feel diffident in advancing it here; I must, therefore, invite the reader to accept it cum grano salis, like all other theories that have not stood the crucial test, which, for various reasons, I must leave to the care of greater capacities, if they think it worth their while. If the single bond of an asymmetrical carbon-atom changes into a double bond, the compound becomes inactive because the carbon-atom has lost its freedom to rotate round the common axis as described before, and screw-formation is made impossible, still two isomers are possible ; but with the system of symbols we have been using their differences cannot find ready expression. Malic acid is the best known example of this. STBREO-OHEMISTRY The pictorial form we have given to malic acid (fig. 727, p. 186) was 473 Fia. 1589 Its two active and one inactive stereo-isomers are explicable exactly in the same way as were those of lactic acid, and need therefore not be repeated. When the hydroxyl and its neighbouring hydrogen are removed in the form of water, the remaining free valencies will form a double bond : Fio. 1590 This figure represents two isomeric compounds : maleic acid and fumaric acid. Now we will see how their differences can be explained by the tetrahedron system. The conversion of malic acid into maleic acid may be illustrated thus : Fig. 1591 FiQ. 1592 Fio. 1593 Malic acid Double boud in course of formation Maleic acid As regards the positions of the carboxyl-hydroxyls the remarks made on p. 465 hold good here 0. The carboxylic hydroxyls in this structure of maleic acid will be seen to be in close proximity. Maleic acid will therefore easily form an anhydride by dropping a molecule of water formed from the 474 ATOMS two hydroxyls when they come opposite each other (represented in the above figure), as they will do when the oscillations of the carbon-atoms are sufficiently increased by the application of heat. Pio. 1594 Maleio anhydride The arrangement of the-carboxyls in maleic acid is, however, not the only one possible ; -one of them may exchange places with the hydrogen-atom on its neighbouring carbon-atom, and the carboxyls, instead of being in close proximity to one another, will then be as far distant as possible. This arrangement, supposed to be present in fumaric acid, is, however, not accomplished by any jumping about of the hydrogen-atom and carboxyl-group, but effected simply by the group to the right in malic acid (fig. 1591) being carried by oscillations, increased by heat, beyond the position represented in fig. 1596, then the alcoholic hydroxyl will come sufficiently near the rear hydrogen-atom in the left-hand group (fig. 1596) to form water and create a double bond between the two central carbon-atoms corresponding to the formation of the double bond in maleic acid (figs. 1591—1593). The following figure illustrates this arrangement : Fia. 1595 Fmnaiic acid Here, evidently, there is no chance for the hydroxyls to form water, and in fact fumaric acid does not form a fumaric anhydride, but is when heated to 200° converted into maleic anhydride. "When the double bond is broken and formed into a single bond by introduction of hydroxyl and hydrogen, both acids are recenverted into malic acid : these are all facts that find their ready explanation in the figures. It may be asked if malic acid cannot be arranged in a similar way by having one of its carboxyls removed from its proxdmifry to the other carboxyl and placed upon one of the two vertices of the carbon-atom occupied by hydrogen and hydroxyl, thus forming two more isomers, consequently four STEREO-CHEMISTRY 475 altogether, or five including the inactive modification, composed of equal numbers of molecules ot the two active compounds. Such isomers are not known, and cannot according to our theory exist, because the carbon-atoms would at once revert to their old position on account of the carbon-atoms 1 and 2 being connected by a single bond, and their consequent movability round their common axis (a : b) in the following figure : Fio. 1596 Pia. 1597 The alcoholic hydroxyl in the group 2 is in fig. 1597, facing a hydrogen in the group 1, biit not m fig. 1596; consequently the former is a more favoured arrangement into which the latter will revert by a turn round the axis a : b, unless the oscillations through heat become sufficiently increased for the formation of fumaric acid. Pumaric acid may be converted into malei'c acid, and vice versd, by different degrees of heat, thus confirming the correctness of the theory. Another experiment has been successfully carried out on the basis of this very theory, furnishing a brilliant confirmation of its truth so far ; I refer to the conversion of members of the oleic acid-series into their respective isomers of elaidic acid (Ber. xxiv. p. 4120). Brucic acid is such a compound, which being -an oily liquid is turned into the crystalline isomer brassidic acid (vide fig. 753, p. 193) through nitrous acid. We have given the two acids the same structure because their differences are not conveniently expressible in our symbolic language : PiQ. 1598 Brucic and brassidic acids As the process entirely concerns the doubly linked carbon-atoms, these two only will be repre- sented as tetrahedrons, retaining for the rest of the chain on all the other sides the geometrical symbols with which we now, I hope, are sufficiently familiar ; by limiting the stereometrical repre- sentations to the two actually performing carbon-atoms, the process will be more intelligible ; for the same reason the double bond will be placed next to the carboxyl-link. 476 ATOMS Thus represented the two acids will look like these two illustrations : Fig. 1599 Fio. 1600 Erucic acid Brassidic acid The difi'erence of structure will be seen to be this, that the upper carbon-atom has reversed its position as regards the lower one. This reversion has been effected in the following way : First the double bond has been broken at a. Cpmpounds with double bond in an open chain easily take up by addition two suitable atoms, breaking the double bond, as frequently demonstrated on the preceding pages. Hitherto we have represented this process as being performed by two hydrogen-atoms, but it may be effected just as well, or even Easier, by halogen-atoms, e.g. chlorine. If we then apply chlorine to erucic acid, two such chlorine-atoms will take possession of the two valencies joined by a, which consequently will separate and the two carbon-atoms will assume the structure of single linkage. The process in progress and the finished position will be understood from the following illustrations : Fig. 1601 Fig. 1602 By the addition of the two chlorine-atoms, breaking the double bond of erucic acid, the first step has been made to convert it into the chlorine-compound of the corresponding fundamental acid, STEREO-CHEMISTRY 477 behenic acid (ffg 755, p. 193). It will be noticed that the two chlorine-atoms are in the most proximate positions to be found in the system, two opposite vertices, a position in which there is little stability, and as a consequence the two carbon-atoms try to arrange themselves in a more stable position. That is in this case easily effected in the same way as we have seen it done in a similar case (figs. 1567 and 1568, p. 460). One of the carbon-atoms makes a turn of 120° round their common axis into the most favoured position, whereby one of the chlorine-atoms comes opposite a hydrogen, and the other faces the hydrocarbon body of the acid. We shall let the upper carbon make the movement and the result will be Di-chloio-beheuic acid "We can first, through reducing agents, withdraw the chlorine-atom opposite the hydrocarbon and substitute it by a hydrogen-atom, converting the compound into mono-chloro-behenic acid : FiQ. 1604 Mono-chloro-behenic acid When finally the chlorine and its opposite hydrogen are withdrawn in the form of hydrochloric acid, by an alkali, the two free valencies thereby created close up, formmg a double bond between the two carbon-atoms. 478 ATOMS In order to make this result perfectly understood, the intermediate phase in the process is also here illustrated : Fio. 1605 Fia. 1606 -O-o Formation of the double bond Brassidic acid We have thus arrived at hrassidic acid frora erucic acid. In the same way are to be explained, also, all the stereo-isomerisms mentioned before, e.g. crotonic and iso-crotonic acids, angelic and tiglic acids, &c. It may perhaps be opportune, now, to examine how far the system of symbols we have chosen to represent the atomic linkage agree with these later theories. When we again look at the carbon-atom with its four valencies, as illustrated p. 463, we can by turning it a little to the right, and making it stoop a little from the plane of the paper, give it a form similar to the one we have used all through the treatise : Fig. 1607 STBEEO-OHBMISTRY 479 The configuration of the tetrahedron formed by connecting the ends of the valencies would be As regards single bonds, our symbols would therefore appear correct enough, provided we refrained from representing an open chain in its natural form of a not closed ring. Not quite so correct is our representation of the double bond. In order to be nearer the truth, as far as we know, the valency c should remain in position, and not bend towards the other carbon- atom, and the connection should take place along the line c h. Thus the three acids, malic, maleic, and fumaric, represented as truly as possible when drawn as a projection on a plane, would be Fig. 1609 FiQ. 1610 Fia. 1611 o-ff ■T3 Malic acid Maleic acid Fumaric acid It is obvious how bewildering such a true representation would be, especially in more complex compounds with several double bonds; the two advantages which it should possess, its closer proximity to truth, and hence its capability of showing the stereo-isomerism, are as nothing to the absence, contingent thereupon, of uniformity, intelligibility, and aptitude to impress the memory ; moreover, triple bonds, anyhow, could not be depicted without having recourse to perspectivity. It would be an improvement to let the double bond form two parallel lines instead of a square, and stretch the legs of the carboxyl into the straight line ; but even then the uniformity and conse- quent comparability with other structures would be greatly impaired. I will show this by samples thus constructed and compared with the system adopted in this treatise : 480 ATOMS StBBEOMETBIO StEUCTUEES represented aEOMBTBIOAUiT Fia. 1612 6 Succinic acid Fio. 1614 Maleio acid Fio. 1616 Citiaconic acid Fio. 1618 Mesaconic acid Fio. 1619 Geometeio Strixotures Fio. 1613 O- Succinio acid {vide fig. 714, p. 185) Fio. 1615 Maleio acid (vide fig. 762, p. 195) Fig. 1617 9 Citraoonic and mesaconic acid (vide fig. 763, p. 195) Fig. 1620 O- -# — O Itaoonic acid Itaconic acid (vide fig. 764, p. 196) STEEEO-OHBMISTRT 481 The whole difference now between the two systems is that the doubly linked carbon-atoms with all their appendices are in the stereometric structures given an upward or downward turn of 45° from the horizontal position in which they are placed in the system of this treatise. There is thus a gain to them individually, but a loss considered as a whole ; the loss is, in my opinion, greater than the gain, because the derivation of one from another is not easily grasped, and they are there- fore not so easily retained in memory. They are, however, generally and necessarily employed by chemists who wish to demonstrate the stereometrical differences by the instrumentality of the usual chemical letter-symbols with the minor alteration of the double bonds being placed perpendicularly. Thus the above compounds, as written in the ordinary chemical language, appear as follows : 00„H— (OH).— 00,H H— 0— OO^H H— 0— GO,H OO^H-^O— H 00,H— 0— OH — CO^H II II ■ II P H— C— OO^H OH3— 0— OOjH CH3— 0— CO,H H— 0— H Suooinio aoid Maleio acid Citraoonio acid Mesaoonio acid Itaoonio aoid which correspond exactly with the above. As regards the closed singly linked rings the system used has another inaccuracy, which it shares with practically all other similar representations, that is, the placing of valencies inside such ring, as the theory supposes. The illustration of part of a hexagon or pentagon will suffice to show that all valencies are outside : Fia. 1621 A more correct representation of benzene-hexa-hydride (fig. 1 24, p. 26) would therefore be Fio. 1622 Benzene-lieia-hydrid But the other way of representing this ring offers so many advantages m itself and its relation to rSffS with double bonds, that although sometimes compelled, by want of room inside the ring to pl^Kvalencies outside according to the above diagram, yet preference has been given to the ring with inside valencies, in spite of its incorrectness. ^ ^ 482 ATOMS A suggestion of rather recent date places all the inside bonds of the benzene-ring in diagonal position (fig. 290, p. 55). By our system this was expressed by the following figure : Supposing the tetrahedron-theory to be correct, there is only one mode of placing the carbons in such a way as to meet this exigency, viz. to put the tetrahedrons close together flat down on a plane : Fia. 1624 Benzene (with diagonal bonds) Seen from the bottom it must be represented thus : Fio, 1625 Seen from the top the ring would therefore appear thus : Fia. 1626 In the position represented by these figures there are evidently six double bonds, part of each affinity being spent in keeping together the six vertices in the centre. But we know they are not assumed to be at rest there ; they must be supposed to vibrate round axes lying in the line of their outside edges : a:b, b: c, c:d, &c., oscillating at a tremendous rate, probably under 600 billions per second, which is the rate of the light's average vibrations, but certainly much more than 500,000 millions per second, the number of the molecule's mutual collisions in a gas. If these vibrations are not synchronal, and individually perhaps not even equally rapid, some at times slower and others quicker, then there will be an ever-changing number and kind of bindings, varying from STBREO-OHBMISTRY 483 none to six of wholly , or partly, double or single bonds, and not only diagonal bonds, but also linkings in all sorts of cross-ways. As in all similar cases, so also in this, there must be a position that represents the mean of them all, and that may, under ordinary circumstances, be the one in which there are three double bonds and three single ones ; in other words, Kekul6's formula. With circumstances altered everybody's formula may in turn be equally favoured. Thus they may all be right ; a state of things I have already indicated on an earlier occasion (vide p. 55). If more than six hydrogen or other atoms or groups are added to the ring, the respective tetra- hedrons wheel round the said axes, a : &, b : c, c : tZ, &c., changing front until they have reached the positions indicated in fig. 1621, p. 477, the two valencies being then on the outside of the ring. When, for instance, two carboxyls are added, di-hydro-phthalic acids are obtained (comp. p. 218"). PiQ. 1626 a Fio. 1626 b Cis-A"-' di-hydro-phthalio acid Trans-A^-' di-hydro-phthalio acid The cis' or maleinoid-form (vide p. 219) is also designated as flam-symmetrical, and the position of the carboxyls as corresponding ; the i/rans- or fumaroid-form as asdal-symmetrical The designar tions maleinoid and fumaroid are, of course, derived from maleic and fumaric acids, in which the carboxyls are supposed to be similarly placed; the others explain themselves. The diagonal structure was originally propounded by Glaus, and therefore generally bears his name • it is however, sometimes termed Loschmidt's or Korn&r's formula. According to Bewa/r, the carbon-atoms 1 : 4 are linked by a single bond, 2 : 3 and 5 : 6 by double bonds. An improvement upon Claus's formula is termed Vauhel's, in which the apices turn alternately in opposite du-ections, consequently thus : Pia. 16260 Pis- 1*526 d Top view The fact however, remains that no single one of the many propounded structures meets the reauirements of the benzene-ring; but any of the chemical reactions and physical properties, so far TsThey -e known, may be explained by either one or the other. 484 VALENCIES VALEITOIES I cannot conclude my work without referring to that which is perhaps the most perplexing character of the atoms, namely, their varying powers of combination with other atoms. We have seen carbon as a dyad and a tetrad, sulphur as a dyad, tetrad, or hexad, nitrogen and phos- phorus as triads or pentads, and the former perhaps also as monad. Hydrogen we have seen as a monad under all circumstances, and likewise chlorine, although inorganic chemistry teaches us that the latter is even more changeable than any of those previously mentioned, being able to appear in no less than four different characters : monad, triad, pentad, and heptad. It is, however, remarkable that this changeable character is shown only in the presence of bodies more electro-negative than themselves. Towards more electro-positive bodies their valency is invariable, chlorine always uniting with one hydrogen-atom, sulphur with two, nitrogen with three, and carbon with four, provided that only one atom of any of the said elements enters into the combination. Chemists have long been unwilling to attribute such a changeable property to the elements, as it somewhat disturbs our ideas of the absolutely unalterable properties of atoms, and many ingenious devices have been propounded in order to steer clear of the rock ; but it has only led to such absurd consequences that they had to submit to the assumption of the apparent inconstancies of the elements in this respect. I am not aware of any existing theory propounded to explain this property, now accepted as a fact, but the discovery of hydrazoic acid, combined with the supposition, gaining more and more ground, that the elements are not simple indivisible bodies, but compounds which we have hitherto been unable to further decompose, seems to throw more light upon this subject. We mentioned (p. 384) that hydrazoic acid had a close resemblance to hydrochloric acid in its chemical properties ; that, in fact, the combination of the three nitrogen-atoms, like an element, played a part very similar to that of chlorine in their respective combinations with other elements or groups. If we now accept the hypothesis of the elements being compound bodies, each atom consisting of several micro-atoms, the idea suggests itself that these micro-atoms may be tied together, like our present atoms in hydrazoic acid, by single or double bonds. In this way the valency-variations are readily explained. Some illustrating examples will interpret the idea, if required. Suppose chlorine consisted of three triad micro-atoms combined like the three nitrogen-atoms in hydrazoic acid, an atom and a molecule of chlorine and hydrochloric acid would have such structure : Fig. 1627 -4 Hydrazoic acid {vide fig. 1373, p. 384) Fig. 1627 a Fio- 1628 Fio. 1629 Atom of chlorine Molecule of chlorine Molecule of hydrochloric acid VALENCIES Chlorine's combinations with oxygen would be ^10- 1630 Fia. 1631 Pia. 1632 485 Fia. 1633 -# — K) d <^ — "O o — ^H-^ Hypoohlorons aoid,' Ol(OH) Chlorous acid,' CIO(OH) Ohlorio acid, C102{0H) Fia, 1634 Perchloric aoid, 0103{OH) Fio. 1635 HypocMorous anhydride, Chlorine peroxide, chlorotetroxide, CI2O4 ; may be regarded ClaO as a mixed anhydride of chlorous and ohlorio acids How far figs. 1632, 1633, and 1635 are probable, some of the micro-atoms being kept together only by oxygen, with no direct binding between themselyes, I shall not say ; by supposing seven micro-atoms in an ordinary atom, which is more likely, such direct bindings can in all cases be esta- blished. I have purposely chosen three, in order to keep up the analogy to hydrazoic acid. It should be remeinbered that chlorine's combinations with oxygen are all very loose, often decomposing with an explosion into the constituent elements. The other elements may also be supposed to consist of micro-atoms with always three valencies. Thus carbon may have four tri-valent micro-atoms : Fia. 1686 Fio. 1637 Fio. 1638 Tetra-valent carbon Di-valent carbon Methane w Carbon dioxide Carbon monoxide • The constitution of the compounds mentioned on p. 271 as containing in their structures radicals of the hypothetical ■ iodons and hypo-iodous acids has, on later and closer examination, proved very different from what it was at first supposed to be (Ber. xxvii. p. S02) ; these compounds are, now, ascertained to be substitution-products of an, as yet, hypothetical body, HO I— H2, which, analogous in its structure to hydroxyl-amine, HO— N— H^ (fig. 1129, p. 318), is in chemical character more nearly' related to the, also, hypothetical ammonium-hydroxide, HO— N — H^ (fig. 1106, p. 312), and sulphiue-hydroxide, 20 S H (comp. p. 286), for which reason the name of iodormmi-hydroxide, and change of name of sulphine into sulphoniim, have been proposed. The two hydrogen-atoms in iodonium-hydroxide may be replaced by phenyls or iodo- phenyls and the hydroxyl by iodine, e.g. HO-I^y. Tri- and penta- valent or Nitrous anhydride, N^Og; the second structure is the anhydride of hypo- nitrous acid, fig. 1648 b, and nitric acid, explaining its composition from, and decomposition into, nitric peroxide and nitric oxide Nitric anhydride, N2O5 Fio. 1655 Nitric peroxide, N^Ot VALENCIES 487 Phosphorus atomic value is analogous to that of nitrogen, and may therefore be assumed also to contain five micro-atoms. A mono-valent phosphorus is, however, unknown : Fio. 1656 A molecule of phosphotna in the gaseous state, F4 Fia. 1657 Fio. 1658 FiQ. 1659 Gaseous phosphoretted hydrogen Liquid phoephoretted hydrogen, (phosphine), PH3 FaH* Solid phosphoretted hydrogen, P^H, Fig. 1660 Fig. 1661 Fig. 1662 FiQ. 1663 ^)0— €H-0 Hypophosphorons acid, Phosphorous acid, HP0(0H)2 ; Phosphoric acid, PO(OH)s ; H2P0{0H); monobasic dibasic tribasic Metaphosphoric acid, P02(0E) ; monobasic 488 Fio. 1664 Phosphorous anhydride, P^Og ; pro- duced, as the structure shows, from four molecules of phosphorous acid by anhydride formation separating six molecules of water VALENCIES Pio. 1665 Hypophosphorio acid, (P0(0H)2)2 ; is a combination of phosphorous and phosphoric acid by elimi- nation of a molecule of water (anhydride formation) ; tetrabasio Jia. 1666 P-yrophosphorio acid, (0H)2P0-0-P0(0H)a; is evidently two molecules of phosphoric acid joined in anhydride fashion ; tetra- basic Fig. 1667 Phosphoric anhydride, P2O5 ; anhydride of meta-phosphoric acid consistent with its mode of preparation In sulphur we may assume six tri-valent micro-atoms : FiQ. 1668 Di-valent sulphur PiQ. 1671 FiQ. 1669 Fio. 1670 1^ Tetra-valent sulphur Fig. 1672 Fig. 1673 Hexa-yalent sulphur Fig. 1674 Hexa-valent atoms ; a molecule Tetra-valent atoms ; a molecule Di-valent atoms; a molecule An atom of of rhombic sulphur of sulphur gas at 500° = Sg of sulphur gas at 1000° - Sj sulphur = S VALENCIES 489 For economy of space rhombic sulphur is here represented as a molecule of eight atoms ; the exact number is not known, but is probably a multiple of six. All the micro-atoms are here united by single bonds. In mono-clinic sulphur, which is formed by heating, a double bond is supposed to be formed inside each atom between two micro-atoms, easily re-arranged into single bonds, recon- verting the sulphur into the rhombic modification. In sulphur-gas at 500° the molecules are split up into smaller molecules of six atoms ; in the atoms are, according to the hypothesis, the same double bindings between the micro-atoms as in the mono-clinic sulphur. The sulphur-gas at 1000° is known to have a molecular combination of two atoms, in each of which the theory supposes two double bonds. Finally the atom of sulphur, which can only exist in free state at very high tem- peratures, has three such double bindings. The increased formation of double bonds as the temperature rises is in full accord with the tetrahedron-theory (vide p. 461) ; though the micro- atoms are not represented as tetrahedrons, still the theory must be sauce for both goose and gander. Fia. 1675 Sulpharetted hydrogen, SH, Pia. 1677 Fio. 1678 or Sulphur dioxide (sulphuryl), also called sulphurous anhydride, SOa Fig. 1679 Sulphur trioxide, also called sulphuric anhydride, SO3 FiQ. 1680 *-@ — -o Hypo- or hydro-sulphurous acid, 0H(S0)20H or (0H)S02-S-(0H) ; dibasic The second formula gives a ready explanation of its decomposition first into thiosulphurio acid and then into sulphur dioxide, sulphur, and water, and is therefore perhaps more correct than the first, which is, however, the one generally given. Fig. 1681 Fio. 1682 '#« Symmetrical sulphurous acid, SO(OE), ; hypoth.; dibasic Common sulphurous acid, HS02(0H). Both hydrogens are replaceable by bases, and the acid is therefore dibasic. This structure is a necessary consequence of the formation of sulphurous ethers from meroaptans and thio-ethers by oxidation. No acid ethers are known of the symmetrical sulphurous ethers, but both acid and neutral ethers are known from the common acid 490 VALENCIES Fia. 1683 o* — (iH* -^—o Di-thionio acid, OHISOaj^OH ; dibasic ; may be considered a combination of sulphuric and Bulphurous acids in anhydride fashion Pre. 1685 Sulphuric acid, S02(0H)2 Di-sulphurio acid, OH(S02)0(SO2)0H ; is two molecules of sulphuric acid joined in anhydride fashion ; dibasic Fro. 1687 O* — (^)— » Thio-sulphurio acid, (0H)S02(SH) ; dibasic. This -will Tri-thionio acid, 0H(S02)S(S02)0H ; formed by the connecting be recognised as sulphuric acid in which sulphur has oxygen in di-sulphuric acid being displaced by sulphur, or displaced an oxygen-atom in one of the hydroxyls from thio-snlphuric acid and sulphuric acid, a molecule of each joining in anhydride fashion The structures of tetra- and penta-thionic acids are generally represented as a row of sulphui> atoms with a radical of sulphurous acid at each end. Fio. 1688 Tetra-thionic acid, Si04(0H)2 ; dibasic Fio. 1689 Penta-thionic acid, S504(0H)2 ; dibasic FINIS 491 They are, however, not very likely structures, such stringing single atoms in a row of an open chain being most improbable; the structures are no doubt more complicated. There are several other ways of arranging them, but so little is known of them that the following is little more than guess-work. Fio. 1690 It explains the decomposition of the acid into sulphurous acid, and of the penta-thionates into tri- and tetrar-thionates, with separation of sulphur; its formation, however, from barium thio- sulphate and chloride of sulphur is less striking than by the string structure. So far then, the theory works beautifully enough, and has even enabled us to see some old acquaintances in a new light; but the hypothesis has its disadvantage: it rests upon another hypothesis, not much better than a presentiment, viz. the divisibility of our present atoms, the chief support for which is the periodic law of atomic weights, their analogy now and then to homo- logous series, and, if you like, the theory above propounded, a sort of co-operative assurance. Quite the other way as regards the tetrahedron-theory. Founded on facts, it has led to discovery of new facts, and has, therefore, from a chemical point of view, reached a stage nearer truth than its precursors ; yet it is not truth itself. There are still formidable difficulties to surmount, and many yet unborn theories will come and go before chemists, mathematicians, astronomers, and physicists shall agree on all points ; and even then we shall still be far away from that ultimate simplicity which we shall never know — THE TRUTH. 492 ADDENDA The manuscript of this treatise was finished in February 1893, but since it left my hands I have tried to keep it up to date by taking advan- tage of every opportunity offered during the progress of printing. A few corrections occasioned by investigations which did not come under my notice until too late must, consequently, find their place here. Page 31. — Ghrysene is said (Ber. xxvii. p. 952) to have probably this structure: Chrysene Page 108. — Aurin and rosoUo add have been found to behave in some respects like quinone, for which reason their structures and formations from tri-phenol-carbinol have been represented in a way somewhat different from that found on p. 108 (the methyl-group in fig. 468, according to Krafit, is placed on a wrong phenyl); in Ber. xxvi. pp. 172 and 2221 (see also NietzM, Chende d. org. Fcvrbstoffe, 2*® Aufl. p. 88) the following explanation is given by which the elimination of a molecule of w5,ter causes a rearrangement of the bonds only, but no intramolecular jumping about of groups : Tri-phenol-carbinol As a consequence, malachite- green (fig. 1279, p. 361) and para- fuchsine {&g. 1284, p. 362) must have such structures : Malachite-green Page 143. — Oa/rvol. According to Ber. xxvii. p. 814, the structure, fig. 586, is that of iso-carvol ; carvol and another isomer, eucarvol, are represented thus : Fara-fuchsine Page 226. — ^The latest, but probably not last, suggestion of the structure of santonin (Ber. xxvii. Eef. p. 24 ; Arch. d. Ph. ccxxxi. p. 695) is this : London : May 1894. Santonin INDEX Abrastol (mde Asaprol) Abrin, 441 Aceconitio acid, 196 Acetal, 115 Aoetaldehyde, 131 Acetaldehyde-acetic acid, 207 Acet-aldoxime, 319 Acet-amide, 328 Acet-amidine, 331 Aoet-anilide, 341 Aoet-anilide-salioylio ether, 343 Acet-anisidine, 347 Acetenyl, 34, 82 Acetic acid, 129, 165, 171, 175 Acetic acid, glacial, 175 Acetic aldehyde, 131 Acetic anhydride, 207, 256 Acetic ether, 231 Acetic valeric anhydride, 256 Aceto-acetanilide, 343 Aceto-acetio acid, 207, 227 Aoeto-acetic aldehyde, 207 Aoeto-acetic ethyl-ether, 232 Aoeto-amido-phenol, 342 Aoeto-hydroxamio acid, 319 Acetone, 138 Aoeto-nitrile, 420, 425 Acetonyl-acetoxime, 320 Acetonyl-aoetone, 140 Aceto-phenetidine, 348 Aceto-phenone, 140 Aceto-phenone-piiiaeone, 89 Aceto-phorone, 139 Acetozime, 319 Acetyl, 200 Acetyl-acetone, 140 Acetyl-aoid value, 241 Acetyl-aorylic acid, 167 Acetyl-amido-salol, 343 Acetyl-benzene, 140 Acetylene, 22, 39 Acetylene-derivatives, 32 Acetylene-di-carboxylic acid, 174 Acetylene- dichloride, 269 Acetylene-mono-carboxylic acid, 174 Acetyl-ethoxy-phenyl-urethane, 371 Aoetyl-hydroxy-butyrio acid, 239 Aoetyl-hydroxy-phenyl-urethane, 371 Acetyl-phenyl-hydrazine, 380 Acetyl-propionic acid, 228 Acetyl-saponification value, 241 Acetyl-urea, 372 Aoetyl-value, 241 Achroo-dextrin, 159 Acid, 165 Acid-albumin, 437 Acid amides, 327, 328 Acid-anhydrides, 207, 256 Acid, classification of, 168 Acid-diazo-benzene-sulphate, 336 Acid, formation of, 165 Acid, fundamental, 169, 175 Acid, saturated aliphatic, 169, 175 Aoidum sulphocarbolioum orudum, 294 Acid, unsatured aMphatio, 169, 189 Acid- value, 241 Aconitic acid, 171, 174, 196 Aoridines, 340 Acrolein, 132 Acro-pinacone, 78 Acrose, 151, 154 Acryl-aldehyde, 132 Acrylic acid, 171, 190, 375 Active ethylidene-lactic acid, 180 Addenda, 492 Adenine, 377, 441 Adipic acid, 171, 185 Adonitol, 68, 79 ^sculetic acid, 222 ^sculetin, 222 ^sculin, 161, 446 ^thal, 72 Agathine, 338 Agavose, 157 Ajwan-ka-phyl, 97 Alanine, 325 Alantol, 144 Albuminates, 437 Albuminoids, 436 Albuminous substances, 431 Albumins, 432 Alcohol (see also Carbinol), 67 Alcohol-aldehydes, 135, 151, 152 Alcohol, allyl-, 73 Alcohol, amyl-, 70, 71 Alcohol, anisic, 122 Alcohol, aromatic, 83 Alcoholates, 109 Alcohol, benzene-, 84 Alcohol, benzyl-, 84 Alcohol, oaproyl-, 194 Alcohol, cetyl-, 72 Alcohol, cinnamic, 90 Alcohol, couiferyl-, 123 Alcohol, crotyl-, 73 Alcohol, cumic, 86 Alcohol, cyclo-hydrocarbon-, 83 Alcohol, di-acid, 67, 76 Alcohol, di-atomic, 68 Alcohol, di-hydroxy-benzyl-, 106 Alcohol, ethyl-, 67, 70 Alcohol, ethylene-, 67 Alcohol, hept-acid, 68, 80 Alcohol, heptyl-, 72 Alcohol, hexacid, 68, 80 Alcohol, hydroxy-benzyl-, 106 Alcohol-ketones, 151, 152 Alcohol, mesitene-, 87 Alcohol, mesitylic, 87 Alcohol, methyl-, 69 Alcohol, mon-acid, 67, 69 Alcohol, mon-atomic, 68 Alcohol, non-acid, 68 Alcohol, oct-aeid, 68 Alcohol, pent-acid, 68, 79 Alcohol, pentyl-, 70 Alcohol, phenol-, 106 Alcohol, phenol-ether-, 123 Alcohol, phenyl-aUyl-, 90 Alcohol, phenyl-ether-, 122 Alcohol, phenyl-propyl-, 84 Alcohol, phtalyl-, 87 Alcohol, primary, 69 Alcohol, propargyl-, 75 Alcohol, propenyl-,73 Alcohol, propyl-, 70 Alcohol, protocatechuio, 106 Alcohol, pseudo-oumylene-, 88 Alcohol, salicylic, 106 Alcohol, secondary, 69 Alcohol, styrolene-, 85 494 INDEX Alooliol, styrolyl-, 84 Alcohol, tarohonyl-, 72 Alcohol, tertiary, 69 Alcohol, tetraoid, 68, 79 Alcohol, triacid, 67, 78 Alcohol, vauiUio, 123 Alcohol, vinyl-, 73 Aldehyde, 127, 131 Aldehyde, acetic, 131 Aldehyde-acids, 207, 227 Aldehyde, aoryl-, 132 Aldehyde, allyl-, 132 Aldehyde- ammonia, 322 Aldehyde, anisic, 136 Aldehyde, benz-, 134 Aldehyde, benzoic, 134 . Aldehyde, butyric, 132 Aldehyde, oinnamic, 134 Aldehyde, croton-, 133 Aldehyde, formation of, 127 Aldehyde, formic, 130 Aldehyde, glycoUie, 135 Aldehyde-green, 131 Aldehyde, hydroxy-butyr-, 133 Aldehyde, methoxy-benz-, 136 Aldehyde, methyl-, 130 Aldehyde, methylene-ether- protocatechuic, 137 Aldehyde, methyl-protooatechuic, 136 Aldehyde, paraformic, 131 Aldehyde, protooatechuic, 136 Aldehyde, salicylic, 135 Aldehyde, specification of, 130 Aldol, 133 Aldoses, 151, 152 Aldoximes, 319 Alexines, 442 Aliphatic series, 7 Alizarin, 146 Alkali-albumin, 437 Alkeiines, 321, 393 Alkines, 321, 393 Alkyl, 81 Altyl-cyanides, 420 Alkylene, 81 Alkylene, oxide, 115 Alkyl-sulphides, 281 Alkyl-sulphhydrates, 281 Allene, 37 Allo-mucic acid, 188 Allophanic acid, 372 AUoxan, 373 Alloxanic acid, 373 Alloxantine, 375 Allyl, 33, 82 Allyl-alcohol, 73 Allyl-aldehyde, 132 Allylene, 39 AUyl-ether, 114 Allyl-iso-thio-cyanate, 424 Allyl-phenol, 100 Allyl-succinic acid, 171 AUyl-thio-carbamide, 371 Allyl-tri-bromide, 268 Almond-oil, 238 Alphol, 248 Alumnol, 294 Amides, 327 Amides, acid, 327, 328 Amides, alkylated, 828 Amides, secondary and tertiary, 328 Amidines, 331 Amido-acetic acid, 324, 356 Amido-acids, 324, 363 Amido-bases, 313 Amido-benzene, 313, 335 Amido-benzene sulphonic acid, 367 Amido-benzoic acid, 326 Amido-benzoyl-formio acid, 364 Amido-oaproiic acid, 325 Amido-cinnamic acid, 366 Amido-cinnamie aldehyde, 367 Amido-compouuds, 313 Amido-oresol, 358 Amido-crotonio acid, 326 Amido-ethane-sulphonic acid, 367 Amido-ethylene-laetio acid, 325 Amido-formic acid, 324 Amido-glyceric acid, 325 Amido-group, 313 Amido-hydro-cinnamic acid, 366 Amido-iso-caproic acid, 325 Amidol, 357 Amido-mandelic acid, 364 Amido-naphthol-sulphonic acid, 351 Amido-phenetol, 346 Amido-phenol, 321 Amido-phenol-derivativea, 346 Amido-phenyl-acetic acid, 363 Amido-propionic acid, 325 A mido-succinamic acid, 329 Amido-succinic acid, 325 Amine, 313 Amine-acids, 328 Aminic acids, 327 Ammelide, 423 Ammeline, 423 Ammonia, 312 Ammonia-bases, primary, 313 Ammonia-baseB, primary, derivatives, 341 Ammonia-bases, secondary, 314 Ammonia-bases, secondary, derivatives, 352 Ammonia-bases, tertiary, 315 Ammonia-bases, tertiary, derivatives, 353 Ammonium, 312 Ammonium-acetate, 323 Ammonium-bases (quartemary), 316 Ammonium-bases (qnartemary),_ derivatives, 354 Ammonium-chloride, 323 Ammoninm-cyanate, 422 Ammonium-formate, 323 Ammonium-hydroxide, 312, 485 Ammonium-phenyl-sulphonate, 368 Ammonium-salts, 323 Amphi-creatinine, 441 Ampho-deutero-albumose, 437 Ampho-peptone, 437 Amygdalin, 446 Amyl, 10 Amyl-acetate, 232 Amyl-alcohol, 70, 71 Amylene, 19, 20, 23, 35, 36 Amylene, commercial, 36 Amylene-hydrate, 72, 129 . Amyl-nitris, 304 Amylo-dextrin, 159 Amyloid, 158 Amylopsjn, 445 Amyloses, 151 Analgene, 407 Analgesiue, 343 Anethol, 117 Angelic acid, 171, 191 Angio-neurosine, 310 Anhydrides, 256 Anhydro-amido-phenyl- carbonic acid, 342 Anilides, 341 Aniline, 313, 335 Aniliae-dyes, 360 Aniline-yellow, 335 Anions, 280 Anisic acid, 251 Anisic alcohol, 122 Anisic aldehyde, 136 Anisidine, 346 Anisoil, 116 Anisol, 116 Anniladin, 270 Anode, 279 Anodynine, 343 Anol, 100 Anthracene, 59 Anthraoene-di-hydride, 59 Anthracene-phenol-alcohols, 107 Anthraflavic acid, 147 Anthra-hydro-quinone, 141 Anthranilic acid, 326 Anthranol, 91 Anthra-quinone, 141, 142 Anthrarobin, 107 Anthrarufin, 147 Anthrax-bacillus, 446 Anthrax-protein, 441 Anti-acetaldoxime, 320 Anti-albumid, 437. Anti-albumin, 437 Anti-albuminate, 437 Anti-aldoxime, 320 Auti-cholerin, 442 Anti-deutero-albumose, 437 Antidiphtherin, 442 Antifebrine, 341 Antikamine, 345 Antikol, 341 Antiuervine, 342 Antinonnine, 308 Anti-peptone, 437 Antiphthisin, 442 Antipyrine, 343, 382 Antipyrine, Bohringer, 344 Antipyrme-bromide, 344 Antipyrine-iodide, 344 Antipyrine, Knorr, 343 Antipyrine-salicylate, 345 Antirheumatine, 353 Antisepsine, 342 Antiseptin, 97 Antiseptol, 411 Antithermine, 339 Antitoxins, 441, 442 Apiol, 121 Apo-, 400 INDEX 495 Apo-atropine, 400 Apo-oinohene, 410 Apo-oodeine, 417 Apo-morphine, 417 Aposorbio aoid, 171, 172 Arabin, 151 Arabinose, 151 Arabitol, 80 Arabonio aoid, 171 Araobidio aoid, 171, 178 Aran's ether ansBsthetio, 267 Araroba, 122 Aibutin, 160 Aiohil, 96 Arecaidine, 403 Arecaine, 403 Areca-nut, 403 Aieooline, 403 Aristol, 270, 485 Aromatio acids, 211 Aromatio alcohols, 83 Aromatic series, 42 Arrow-poisons,'441 Artmann's Creolin, 96 Asaprol (= abrastol), 294 Asbolin, 96 Aseptol, 292 Asparagine, 829,470 Aspartio acid, 325, 438 Aspartio aldehyde, 826 Aspartio amides 329 Asseline, 441 Asymmetrical carbon, 463 Asymmetrical position, 43 Atom, 2, 449 Atomicity, 68 Atomic weight, 8 Atom, movement of, 450 Atom, position in space, 453 Atropamine, 400 Atropic acid, 214 Atropine, 399 Auramine, 141 Aurantia, 314 Aurin, 108, 492 Australene, 51 Axial-symmetrical form, 488 Azelaio acid, 171, 186 Azines, 340, 388 Azo-benzene, 334, 335 Azo-compounds, 384, 335 Azo-ethyl-alcohol, 321 Azo-imide, 383 AzoUdines, 386 Azolidones, 386 Azohnes, 386 Azolones, 386 Azols, 886 Azo-nitro-propyl-phenyl, 886 Azo-oxy-benzene, 334, 335 Azo-ozy-oompounds, 384 Azoxazoles, 888 Azoxines, 390 Azoxoles, 387 BAIiUSTITE, 311 Barbituric aoid, 373 Behenic acid, 171, 178, 193 Behenolio acid, 171, 200 Belladonine, 400 Benz-aldehyde, 134 Benzamic acid, 326 Benz-amide, 830 Benz-amido-aoetic acid, 330 Benz-analgene, 407 Bepz-anilide, 345 Benzauriu, .107 Benz-di-oxy-anthra-quinone, 147 Benzene, 29, 82, 33, 54 Benzene-acids, 211 Benzene-derivatives, 42 Benzene-di-carboxylLc acid, 217 Benzene-di-hydride, 28, 33 Benzene, di-oxy-, 92 Benzene-hexa-oarboxyhc acid, 222 Benzene-hexa-hydride, 26, 33 Benzene-penta-oarboxylic aoid, 222 Benzene-rings, 54, 482 Benzene-sulphinio acid, 288 Benzeue-sulphonic acid, 292 Benzene-tetra-carboxylic acid, 222 Benzene-tetra-hydride, 27, 33 Benz-hydroxamic aoid, 318 Benz-hydroxyl-amine, 818 Benzidine, 358 Benzidine-tetrazo-di-sodium- naphthionate, 337 Benziu, 37 Benzoic acid, 211 Benzoic aldehiyde, 134 Beuzo-naphthol, 249 Benzo-para-oresol, 141 Benzo-phenone, 141 Benzosol, 247 Benzoyl, 201 Benzoyl-eogonine, 402 Benzoyl-formio acid, 213 Benzoyl-guaiacol, 247 Benzoyl-hydrazine, 383 Benzoyl-Bulphimide, 368 Benzyl, 84 Beuzyl-aloohol, 84 Benzyl-amine, 313 Benzyl-carbinol, 84 Benzyl-naphthalene, 56 Berbamine, 416 Berberine, 416 Betaine, 355, 356, 440 Betol, 248 Biazolone, 388 Bile, 367 Bilif ulvin, 436 Bnineurine, 354 BUiphsein, 436 Bilirubin, 436 Biliverdin, 486 Biophene, 286 Bioses, 151, 156 Bismuth-gallate, 222 Bismuth-salioylate, 215 Bitter- ahnond-oil, 134 Bitter-almond-oil, artificial, 806 Bitter-almond-oil-green, 860 Biuret, 372 Blubber oils, 238 Bond, diagonal, 68, 482 Bond, double, 19, 454 Bond, mixed, 41 Bond, triple, 22, 454 Borneol, 98 Bottlenose-oil, 288 Bouquet of wine, 232 Brassidio acid, 193, 476 Brassylic acid, 171 BrUliant-green, 361 Brockmaim's cresolin, 96 Brom-acet-anUide, 342 Bromal-hydrate, 272 Bromamide, 313 Brom-antifebrine, 342 Brom-ethyl, 267 Brom-ethylene, 268 Bromine, 265 Bromoform, 266 Bromol, 269 Bromo-methyl, 265 Bromo-nitro-methane, 305 Butane, 9, 12 Butene, 35 Butenyl, 33, 82 Butine, 21, 28, 88 Butine-glycol, 78 Buton-hexa-carboxylio aoid, 173 Butter, 234 Butter, artificial, 288 Butyl, 10, 82 Butyl-acetylene-carboxylic acid, 171 Butyl-amine, 440 Butyl-chloral, 272 Butyl-chloral-hydrate, 272 Butylene, 85, 86 Butylene-glyool, 77 Butylenyl, 83, 82 Butyl-glycerin, 79 Butyl-hypnal, 845 Bntylidene, 82 Butyr-aldehyde, 132 Butyric aoid, 171, 172, 176, 239 Bntyryl, di-valent, 201 Butyryl, mono-valent, 200 Bz-, 405 Cacao-butteb, 238 Cadaverine, 357, 440 Cadinene, 52 Caffeic acid, 220 Caffeine, 378 Cajeputene, 50 Cajeputol, 99 Camphene, 51 Camphoide 311 Camphor, Borneo-, 98 Camphor, common, 143 Camphor, Japan-, 143 Camphoric acid, 208 Cancrom, 442 Cane-sugar group, 151, 156 Caoutchin, 50 Caoutchouc, 52 Caprio aoid, 171, 177 Caproic acid, 171, 177 Caproyl-aloohol, 194 Caprylic aoid, 171, 177 Caramel, 157 Carballyl, 201 INDEX Carbamio acid, 324, 328, 369 Carbamide, 828 Carbamines, 420 Carbanilic acid, 870 Carbanilide, 371 Carbinol (see also Alcohols), 69 Carbinol, benzyl-, 84 Carbinol, di-allyl-,, 75 Carbinol, di-ethyl-, 71 Carbinol, di-methyl-allyl-, 73 Carbinol, di-methyl-ethyl-, 72 Carbinol, di-methyl-phenyl-, 85 Carbinol, di-phenyl-, 88 Carbinol, ethyl-phenyl-, 85 Carbinol, iso-butyl-, 71 Carbinol, methyl-di-allyl-, 75 Carbinol, metbyl-hexa-methylene- methyl-, 84 Carbinol, methyl-hexyl-, 194 Carbinol, methyl-iso-propyl-, 71 Carbinol, methyl-penta-methylene- methyl-, 83 Carbinol, methyl-phenyl-, 85 Carbinol, methyl-propyl-, 71 Carbinol, phenyl-benzyl-, 88 Carbinol, phenyl-di-phenol-, 107 Carbinol, tetra-methyl-, 72 Carbinol, tolyl-, 86 Carbinol, tri-methyl-, 70 Carbinol, tri-phenol-, 107 Carbinol, tri-phenyl-, 89 Carbinol, vinyl-ethyl-, 73 Carbo-gluoonic acid, 171, 183 Carbohydrates, 151 Carbohc acid, 92 Carbolic acid, crude, 95 Carbolic lime, 95 Carbolic powder, 95 Carbon, 3, 453 , Carbon-atom, asymmetrical, 463 Carbon di-oxide, 179, 184, 485 Carbon di-sulphide, 288 Carbonic aoid, 171, 179, 184 Carbon mou-oxide, 278, 485 Carbon oxy-chloride, 278 Carbon oxy-sulphide, 288 Carbon, stereometric form of, 453 Carbonyl, 130, 138 Carbonyl-amido-phenol, 342 Carbonyl-chloride, 273 Carbonyl-di-thio-acid, 282 Carbonyl-thioxy-acid, 282- Carbostyril, 366, 405 Carboxyl, 165 Carbyl-amines, 420 Cardin, 442 Camanba acid, 178 Camine, 441 Carrotin, 436 Carvacrol, 97 Carvacrol-iodide, 270, 485 Carvene, SO Carvol, 143, 144, 492 Carvomenthene, 49 » Casein, 433, 445 Caseinogen, 433, 445 Caseoses, 438 Castor oil, 288 Catechol, 92 Cateohol-methyl-ether, 118 Catramin, 52 Caulosterin, 90 Cell-albumin, 432 Cell-globulin, 432 Celluloid, 311 CeUulose, 151, 158 Cellulose-group, 151 Cellulose-nitrates, 311 Cerebrin, 435 Cerebrin, 442 Cerotio acid, 178 Ceryl-cerotate, 232 Cetyl-aloohol, 72 Cetyl-palmitate, 232 Chains, 10 Chains, closed, 24 Chains, open, 7, 24 Cheese, 433 CheKdonio acid, 261 Chelen, 267 Chinese rice paper, 153 Chitin, 436 Chloral, 271 Chloral-amide, 369 Chloral-anmionia, 368 Chloral-cyan-hydrate, 421 Chloral-cyan-hydriile, 421 Chloral-formamide, 369 Chloral-hydrate, 272 Chloral-imide, 369 Chloralose, 272 Chloral-urethane, 870 Chlor-ethyl, 267 Chlor-ethylene, 268 Chloric acid, 485 Chlorine, 265, 484 Chlorine peroxide, 485 Chloro-behenic acid, 477 Chloro-carbonic acid, 273 Chloroform, 265 Chloroformio aoid, 273 Chloro-methane, 265 Chlorophyll, 436 Chloropicriu, 805 Ohloro-tetroxide, 485 Chlorous acid, 485 Chloroxal-ethyline, 391 Chloryl, 267 Oholeic acid, 867 Cholepyrrhin, 430 Cholera-bacillus, 446 Cholesterin, 90 Cholic acid, 367 Choline, 354, 440 Chromophanes, 436 Chromo-proteids, 436 Chrysaniline, 340 Chrysarobin, 122 Chrysazin, 147 Chrysazol, 101 Chrysene, 31, 492 Chrysoidines, 335 Chrysophanio acid, 148 Chymosin, 445 Cinohene, 410 Cinchomeronic acid, 394 Cinchonidine, 411 Cinchonine. 410 . Cinchoninic acid, 406 Cinene, 50 Cineol, 99 Cinnamene, 47 Cinnamenyl, 34 Cinnamio acid, 214 Cinnamio alcohol, 90 Cinnamic aldehyde, 134 Cinuamyl, 201 Cinuamyl-oocaine, 403 Cinnamyl-guaiacol, 248 Cinnoline, 390 Cis-, 219, 483 Citraconic aoid, 195 Citramalic acid, 187 Citrene, 50 Citric acid, 171, 173, 189 Cocaine, 402 Cocethyline, 403 Codeine, 417 Cod-liver oil, 238 CoUagen, 486 CoUidines, 393, 440 CoUodium, 311 Colloids, 437 Colloxylin, 311 Colophen,.52 Combustion, 66 Compound ethers, 207, 231 Compound liquid, 265 Compound proteids, 433 ConchioHn, 486 Congo-red, 337 Conhydrine, 396 Coniferin, 160, 446 Coniferyl-alcohol, 123 Conine, 396 Conydrine, 396 Conyrine, 392 Copellidines, 397 Cordite, 311 Corresponding positions, 483 Corridines, 393 Corrosive subHmate, 267 Cotarnio acid, 412 Cotarnine, 413 Cotton-oil, 238 Coumaric acid, 216 Coumario anhydride, 216 Coumarin, 216 Creasote, 119 Creasote, oleo-, 244 Creatine, 874 Creatinine, 875, 441 Creolin, 96 Creosol, 119 Creosotal, 244 Creosote, 119 Cresalol, 246 Cresol, 95 Cresolin, 96 Cresol-salicylate, 246 Cresol-sulphonic acid, 294 Cresorcinol, 96 Cresotic acid, 223 Crooeic acid, 294 Croton-aldehyde, 133 Oroton-chloral-hydrate, 272 Orotouio acid. 171. 174. 190 INDEX 497 Orotonio aoid, iso-, 190 Crotonyl, 33, 82 Crotonylene, 89 Crotyl-aloohol, 73 Cruso-oreatinine, 441 OrystaUin, 433 Crystalline, 311 OrystaUoids, 437 Crystal-violet, 363 Cumeue, 44 Cumio alcohol, 86 Cupreine, 411 Cyamelide, 422 Cyan-etlioliiie, 423 Cyan-hydrine, 421 Cyanic acid, 422 Cyanogen, 419 Cyanuric acid, 423 Cyclo-aeids, 207 Oyclo-hydrocarbons, 24, 42 Cyclo-pentadiene, 28 Cymene, 29, 45, 54, 74 Cymene-di-liydride, 50 Cymene-hexahydride, 48 Cymene-tetra-hydride, 49 Cymene-tri-hydride, 50 Cymogene, 37 Cymo -phenol, 97 Cystine, 325 Dahbose, 94 Daphnetin, 222 Oaturine, 400 Daucosterin, 90 Deca-hydro-quinoline, 408 Decane, 9 Deoylenic acid, 171 Dehydro-tri-chlor-aldehyde-phenyl- di-methyl-pyrazolone, 344 Delphinic acid, 176 Dermatol, 222 Desmotropism, 93 Desoxalio aoid, 171, 189 Desoxy-alizarin, 107 Developers, photographic, 357 Dextrin, 151, 159 Dextrin, achroo-, 159 Dextrin, amylo-, 159 Dextrin, erythro-, 159 Dextrose, 151, 153, 426 Dextrose-carboxylio acid, 426 Dextro-tartaric acid, 187, 464 Diabetin, 153 Di-acetln, 283, 284 Di-acetyl, 140 Di-acetylene, 22, 40 Di-acetylene-oarboxylic aoid, 174 Di-acetyl-hydrazone, 339 Di-acetyl-osazone, 339 Di-acid alcohols, 67, 76 Di-acid phenols, 92 Di-aldehydes, 132 Di-allyl, 28, 38 Di-allyl-acetio acid, 171, 197 Di-aUyl-oarbinol, 75 Di-allylene, 41 Di-allyl-oxaUc acid, 171 Dialurio acid, 373 amido-benzene, 317 amido-di-phenyl, 358 amido-phenol, 357 amines, 317, 356 aphterine, 407 astase, 445 astase, secretion-, 445 astase, translocation-, 445 aterebic acid, 171 atomic alcohols, 68 azines, 889 azo^-beuzene, 337 azo-benzene-butyrate, 337 azo-benzene-imide, 383 azo-compounds, 336 azo-ethoxane, 801 benzyl, 47 carvaorol, 105 chlor-acetic acid, 273 chlor-ethylene, 269 ohlor-ethylene-chloride, 266 chlor-ethylidene-ohloride, 266 chloro-behenic acid, 477 cymene, 57 ethoxyl-amine, 321 ethyl-aoetal, 115 ethyl-amine, 814 ethyl-carbinol, 71 ethylene, 20, 37 ■ethylene-derivatives, 28 •ethylene-di-amine, 358 •ethylene-isomers, 21, 38 •ethylene-oxide, 115 ■ethylene-tri-amine, 317 ■ethyl-hydrazine, 332 ■glycerides, 233 ■glycerin, 116 ■heptyl-acetic acid, 177 ■hexoses, 151, 156 •hydro-lutidine, 441 ■hydro-phthaUo acids, 218 ■hydro-quinoline, 408 ■hydroxy-adipio acid, 171 ■hydroxy-anthracene, 101 ■hydroxy-benzyl-alcohol, 106 ■hydroxy-butyrio acid, 171, 172 ■hydroxy-oaproio aoid, 171 •hydroxy-cinnamic acid, 219 ■hydroxy-oiimamic anhydride, 220 ■hydroxy-heptylic acid, 171 ■hydroxy-iso-citrio aoid, 171, 173 ■hydroxy-jecoleic aoid, 171, 181 •hydroxy-maleio acid, 171, 174 ■hydroxy-naphthalenes, 104 ■hydroxy-steario acid, 171, 181 ■hydroxy-tartaric acid, 171 ■hydroxy-undeoylic acid, 171 ■hydroxy-valerio, 171 ■imines, 359 ■iodo-oleic acid, 242 iodo-phenol-iodide, 271 iodo-phenol-sulphonio acid, 293 iodo-reeoroin-iodide, 271 iodo-resorcin-sulphonic acid, 293 iodo-salicylio aoid, 273 iaatogen, 309 iso-amyl, 17 iso-amyl-oxalio acid, 171 ■isoprene, 60 -iso-propyl, 16 iso-propyl-butine, 29 keto-butaue, 140 ketone, 140 lactic aoid, 258 -methyl-allene, 38 -methyl-allyl-carbinol, 73 methyl-amido-aoetic-methyl- ether, 356 methyl-amine, 314, 440 methyl-butinyl-iso-propyl- methane, 29 -methyl-di-aoetylene, 40 methyl-di-ethyl-sulphone- methane, 290 methyl-di-iso-butyl-di-benzene, 57 methyl-ethyl-oarbinol, 72 methyl-ethylene-glycol, 77 methyl-ethyl-methane, 14 -methyl-gallic acid, 412 methyl-iso-heptyl-methane, 17 methyl-ketone, 127, 128, 138 methyl-naphthol, 103 methyl-oxy-quinizine, 343 methyl-pentyl-methane, 17 methyl-phenyl-oarbiuol, 85 methyl-phenylene-naphthalene, 61 methyl-propyl-methane, 15 -methyl-pyridiue, 392 ■methyl-salicylate, 245 ■methyl-sulphine-oxide, 287 ■methyl-sulphone, 289 -methyl-sulphoxide, 287 ■methyl-tetra-acetylene, 41 ■methyl-urea, 441 naphthalene, 58 ■nitro-cresol, 308 -nitro-di-phenyl-di-aeetylene, 309 -octyl-acetio acid, 178 oxindole, 364 oxy-benzene, 92 oxy-thio-carbonic apid, 283 -pentene, 50 ■pentenylene-glycol, 98 ■phenol, 104 ■phenyl, 57 ■phenyl-acetylene, 55 ■phenyl-amine, 314 phenyl-amine-blue, 814 ■phenyl-benzene, 58 •phenyl-oarbinol, 88 ■phenyl-di-acetylene, 56 ■phenylene-methane, 59 ■phenyl-ethane, 47 ■phenyl-ethylene, 48 ■phenyl-hydrazine, 382 -phenyl-ketone, 141 ■phenyl-methane, 46 ■piperideine, 398 ■propargyl, 40 ■propinyl, 40 ■saccharides, 151, 156 ginfectants, 95 ssociation, 278 sulphides, 281 sulphuric acid, 490 thio-benzoic acid, 283 thio-hydroxy-benzoic aoid, 284 ithion, 285 K K 498 INDEX Dithionic acid, 490 Di-thio-salicylic acid, 285 Di-thioxy-oarbonio acid, 282 Di-thymol, 105 Di-thymol-iodide, 270 Diureides, 372, 37.5 Diuretine, 378 Di-valerylene,. 50 Docosane, 9 Docosylene, 37 Dodecane, 9 Doeglic acid, 192 Drying oils, 238 Duboisine, 400 Dugong-oil, 238 Dulcine, 347, 371 Duloite, 80 Dulcitol, 80 Dutch liquid, 267 Dyad, 3 Dyad Bulphur-componnds, 280 Dynamite, 310 EceoNiNE, 401 Sgg-albnmin, 432 EicoEane, 9 Eikonogen, 351, 358 EleebUc acid, 197 Elseomargaric acid, 171, 197 Elseostearic acid, 197 Elaidic acid, 192 Elaiidin, 236 Elastin, 436 Electrodes, 279 Electrolysis, 279, 280 Electrolyte, 279 Electrolytic cell, 279 Electro-negative bodies, 277 Electro-positive bodies, 277 Emodin, 148 Emulsin, 446 Enanthiomorphism, 460 Enzymes, 443, 444 Enzymes, carbohydrate-, 445 Enzymes, glyceride-, 445 Eosin, 47 Eruoic acid, 171, 193, 476 Erucidic acid, 193 Erythrite, 68, 79 Erythritic acid, 172, 181 Erythro-dextrin, 159 Erythro-glucinic acid, 171, 172, 181 Erythrol, 68, 79 Erythro-oxy-anthra-quinone, 145 Erythrose, 135, 151, 152 Essence, artificial fruit-, 282 Essence of mirban, 306 Ester, 231 Ester-acid, 231 Ethane, 8, 12 Ethane-di-carboxylio acid, 185 Ethene, 35 Ethenyl, 11, 82 Ethenyl-amidine, 331 Bthenyl-tri-carboxylic acid, 171 Ethenyl-tri-methyl, 27 Ether-acid, 207, 250 Ether, aliphatic, 113 Ether, allyl-, 114 Ether anaesthetic, Aran's, 267 Ether bromatus, 267 Ether, catechol-methyl-, 118 Ether, compound, 207, 231 Ether, ethyl-, 113 Ether, ethylene-, 115 Ether, ethylidene-, 115 Ether, homo-catechol-methyl-, 119 Ether, hydroxy-benzyl-methyl-, 122 Ether, malonic, 242 Ether, methyl-, 113 Ether, methyl-ethyl-, 113 Ether, methyl-phenyl-, 116 Ether, mixed, 113 Ether, phenyl-, 117 Ether, proto-catechu-aldehyde- methylene-, 137 Ethers, 113 Ether, simple, 113 Ether, sulphuric, 113 Ether, the, 449 Ethidene-chloride, 267 Ethidene-lactic acid, 179 Ethoxy-, 81 Ethoxy-acet-anilide, 348 Ethoxy-caffeine, 379 Ethoxy-hydracetine, 381 Ethoxyl, 81 Ethoxyl-amine, 321 Ethoxy-phenyl, 117 Ethyl, 10, 81, 82 Ethyl-acetate, 231 Ethyl-acetylene, 39 Ethyl-alcohol, 70 Ethyl-amido-phenate, 346 Ethyl-amine, 313, 336 Ethyl-aniline, 314 Ethyl-benzene, 44 Ethyl-bromide, 267 Bthyl-butyrate, 232 Ethyl-carbamio ether, 370 Ethyl-carbonate, 207 Ethyl-carbonic acid, 207 Ethyl-carbonyl- amine, 428 Ethyl-chloride, 266, 267 Ethyl-disulphide, 281 Ethylene, 20, 35 Ethylene-alcohol, 67 Ethylene-bi-chloride, 267 Ethylene-fcromide, 267 Elhylene-chlcride, 266, 267 Ethylene-di-acetate, 288 Elhykne-di-acetin, 233 Ethylene-di-amine, 317 Ethylene-glycol, 76 Bthylene-iodide, 267 Ethylene-lactic acid, 168, 179 Ethylene-mon-acetate, 238 Ethylene-mon-acetin, 283 Ethylene-oxide, 115 Ethylene-succinic acid, 185 Ethyl-ether, 113, 297 Ethyl-formate, 231 Ethyl-glyoxal-ethyline, 891 Ethyl-hydrazine, 832 Bthyl-hydro-snlphide, 281 Ethylidene, 11, 82 Ethylidene-chloride, 266 Ethylidene-glyool, 115 EthyUdene-lactic acid, 168, 179, 461 Ethylidene-succinic acid, 185 Ethyl-iodide, 267 Ethyl-iso-butyl, 15 Ethyl-iso-cyanate, 423 Ethyl-malonate, 242 Ethyl-malonic acid, 242, 243 Ethyl-mercaptan, 281 Ethyl-nitrate, 310 Ethyl-nitrite, 803 Bthyl-phenyl-acetone, 140 Bthyl-phenyl-carbinol, 85 Ethyl-phenyl-ether, 117 Bthyl-pyridine, 392 Bthyl-sulphate, 296 Ethyl-sulphide, 281 Ethyl-sulphinic acid, 287 Ethyl-sulphite, 288 Ethyl-Bulphone, 289 Ethyl-sulphonio acid, 291 Ethyl-sulphonic ethyl-ether, 295 Ethyl-sulphuric acid, 296 - Ethyl-sulphurous acid, 288 Ethyl-toluene, 45 Ethyl-urea, 871 Ethyl-xanthio acid, 288 Eucalyptera, 100 Eucalyptia, 100 Eucalyptic extract, 100 Eucalyptine, 100 Eucalyptol, 99 Eucalyptol-essence, 100 Eucalyptosiue, 100 Euoarvol, 492 Eugenol, 119 Eugenol-acetic acid, 253 Eugenol- acetic amide, 330 Eugenol, iso-, 120 Eulyptol, 216 Euphoria, 370 Europhen, 270, 485 Burophenol, 105 Evaporation, 277, 450 Exalgine, 342 Ezodyne, 341 FABiNoan, 159 Fats, 237 Fats, rancid, 238 Fatty group, 7 FeUic acid, 367 Fermentation, 443 Ferments, 443 Ferments, amylolytic, 444 Ferments, ooagulative, 445 Ferments, glucoside-splitting, 446 Ferments, inversive, 445 Ferments, organised, 443 Ferments, proteo-hydrolytic, 444 Ferments, proteolytic, 444 Ferments, steatolytic, 445 Ferments, unorganised, 443 Ferratin, 438 Ferulio acid, 252 Fibrin, 432, 445 Fibrin-ferment, 432, 445 Fibrinogen, 482 Fibrino-plastic, 432 INDEX 499 Fibroin, 436 Pluoranthene, 60 Fluorene, 59 Formaldehyde, 130 Formalin, 131 Formalith, 131 Formamide, 327 Formamidine, 331 Formanilide, 341 Formic acid, 166, 171, 175 Formic aldehyde, 130 Formic anhydride, 256 Formose, 154 Formyl, 200 Formyl-aoetio acid, 227 Formyl-amido-phenol-ether, 347 Formyl-phenetidine, 847 Frangulinio acid, 147 Fruit-essences, 232 Fruit-sugar, 158 Fuohsine, 362 Fulminate of mercury, 421 Fulminio acid, 421 Fumaric acid, 195, 474 Fumaroid form, 219, 483 Fundamental acids, 169, 175 Fundamental hydrocarbons, 7 Purane, 259 Furazane, 388 Furfur-alcohol, 260 Furfurane, 259 Furfurane-aldehyde, 260 Furfurol, 260 Gadiniite, 440 Gsei'dinic acid, 191 Galacionic acid, 183 Galactose, 151, 155 Gallacetophenone, 145 Gallic acid, 221, 411 Gallotannio acid, 255 Gastric juice, 444 Gasolin, 37 Gelatin, 436 Gelatin, blasting, 311 Geranial, 133 Geraniol, 74 Gingkoic acid, 178 Gliadin, 433 Globin, 436 Globulin, 432 Globulose, 438 Glonoin, 310 Gluoase, 445 Glucogenic acid, 188 Glnooheptitol, 80 Gluconic acid, 171, 172, 183 Glucononite, 68 Gluoo-octite, 68 Gluco-saccharinic acid, 181 Gluoosazone, 155 Glucose, 151, 152, 153 Gluoose-hydrazone, 154 Gluoosidea, 160 Glucoside-splitting ferments, 446 Glucosone, 155 Glutamic acid, 326 iGlutaric acid, 185 Gluten, 433, 445 Gluten-ferment, 445 Gluten-fibrin, 433 Glyceric acid, 168, 171, 181 Glyceride, 233 Glyceride-enzymes, 445 Glycerin, 67, 78 Glycerin, butyl-, 79 Glycerin, hexyl-, 79 Glycerin-nitrate, 310 Glycerin, nitro-, 310 Glycerol, 67, 78 Glycerol, phenyl-, 86 Glycero-phosphorio acid, 434 Glycerose, 151, 152 Glyceryl, 82 Glyceryl-tri-bromide, 268 Glyceryl-tri-chloride, 268 Glyoide, 116 Glycide-alcohol, 116 Glycocholic acid, 367 Glyoocine, 324 GlycocoU, 324, 356 Glycocoll-phenetidine, 348 Glyoocyamine, 374 Glycogen, 151, 159 Glycol, 67 Glycol, butine-, 78 Glycol, butylene-, 77 Glycol, di-methyl-ethylene-, 77 Glycol, ethylene-, 76 Glycol, iso-butylene-, 77 Glycol, mesitylene-, 87 Glycol, methylene-, 76, 114 Glycol, phenyl-, 85 Glycol, propylene-, 77 . Glycol, tolylene-, 87 Glycolide, 182 Glyoollic acid, 167, 171, 179 GlycoUio aldehyde, 135 Glyoolyl, 201 Glycolyl-methyl-guanidine, 375 Glyoo-proteids, 435 Glycoses, 152 Glyoxal, 132 Glyoxalic acid, 171, 180, 227 GlyoxaHne, 387 Glyoxal-osazone, 339 Glyoxime, 320 Glyoxylio acid, 180 Goa-po\?der, 122 Goose-fat, 238 Gossypose, 158 Granulose, 159 Grape-sugar group, 151, 152 Groups, 10 Guaiacol, 118 Guaiacol-benzoate, 247 Guaiacol-carbonate, 243 Guaiacol-carbonic acid, 244 Guaiacol, oleo-, 244 Guaiacol-saUcylate, 247 Guanidine, 874 Guanidine-acetic acid, 374 Guanine, 377, 441 Guavaoine, 403 Gulose, 151, 152, 155 Gun-cotton, 811 Gun-powder, smokeless, 311 Gutta-percha, 52 HaiMATIN, 436 Hffimatogen, 438 Htemoglobin, 436 Halogen-compounds, 265 Halogens, 265 Hedecane, 9 Heliotropin, 137 Helvetia-green, 361 HemeUithene, 45 Hemi-albumin, 437 Hemi-deutero-albumose, 437 Hemimellitic acid, 219 Hemi-peptone, 437 Hemi-proto-albumose, 437 Hemp-oil, 238 Hendecylene, 37 Heptacid-aloohols, 68, 80 Heptadecane, 9 Heptadeoa-tetra-ethylene, 39 'Hepta-methylene, 26 Heptane, 9, 12 Heptone, 41 Heptoses, 151 Heptyl-alcohol, 72 Heptylene, 85, 86 HeptyUc acid, 426 Herring-oa, 238 Hesperidene, 50 Hetero-albumose, 437 Hexacid alcohols, 68, 80 Hexacid phenols, 94 Hexadecyl-alcohol, 72 Hexadecyleue, 87 Hexad-sulphur-oompounds, 289 Hexa-hydro-phthalio acids, 219 Hexa-hydro-quinoline, 408 Hexa-hydro-tetra-hydroxy- benzoic acid, 210 Hexa-hydroxy-benzene, 94 Hexa-hydroxy-benzene-hexa- hydride, 94 Hexa-hydroxy-stearic acid, 171, 183,198 Hexa-methyl-benzene, 46 Hexa-methylene, 26 Hexa-methylene-carboxylic acids, 210 Hexane, 9, 12, 15 Hexine. 38 Hexo-bioses, 156 Hexone, 29, 41 Hexoses, 161, 152 Hexoses, poly-, 151 Hexoses, tri-, 151, 158 Hexoylene, 39 Hexyl-amine, 441 Hexylene, 35 Hexyl-glycerin, 79 Hexyl-lutidines, 898 Hippuric acid, 330 Histozyme, 446 Eom-, 400 Homatropine, 400 Homo-, 400 Homo-catechol, 96 Homo-catechol-methyl-ether, 119 Homo-cocaine, 403 Homologous series, 12 Homo-pyro-oateohin, 96 Homo-quinine, 411 Homo-salicylic acid, 228 . KK2 500 INDEX Homo-salieylide-olilorofonn, 258 Human fat, 238 Hydraoetine, 380 Hydraoetine, ethoxy-, 381 Hydracrylio acid, 179 Hydramines, 321 Hydranthranol, 91 Hydrastine, 415 Hydrastinine, 415 Hydrated benzenes, 33 Hydrated quinolines, 408 Hydration, 33 Hydratropio acid, 213 Hydrazine, 332 Hydrazine,, asymmetrical, 882 t Hydrazine, benzoyl-, 383 Hydrazine-compounds, 332 Hydrazine-deriyatives, 380 Hydrazine-hydroxy-benzoio acid, 381 Hydrazine, nitroso-benzoyl-, 383 Hydrazine-salieylic acid, 381 Hydrazine, symmetrical, 338 Hydrazo-benzene, 333, 335 Hydrazo-compounds, 333 Hydrazo-derivatives, 380 Hydrazoio acid, 383, 384 Hydrazo-methyl-phenyl, 333 Hydrazones, 154, 338 Hydrindigotin, 365 Hydro-antipyrine, 383 Hydro-benzoin, 89 Hydro-bromic ether, 267 Hydrocarbons, 7 Hydrocarbons, oyolo-, 24 Hydrocarbons, fundamental, 7 Hydrocarbons, saturated, 7 Hydrocarbons, unsaturated, 19 Hydro-oarboslyril, 366 Hydro-chloric acid, 484 Hydro-cinnamic acid, 212 Hydro-ooUidine, 440 Hydro-cyanic acid, 419 Hydro-ferri-cyanio acid, 420 Hydro-ferro-cyanio acid, 420 Hydro-muconic acid, 171 Hydro-phthalic acids, 218, 219, 483 Hydro-quinone, 92 Hydro-quinone-methyl-ether, 118 Hydro-sulphurous acid, 489 Hydroxamio acids, 319 Hydroximio acids, 319 Hydroximide, 302 Hydroxy- (see also Oxy-) Hydroxy-acetanilide, 342 Hydroxy-alkyls, 81 Hydroxy-ammonia, 318 Hydroxy-ammonium-chloride, 318 Hydroxy-anthranol, 91 Hydroxy-anthraquinone, 145 Hydroxy-benzoic acid, 215, 216 Hydroxy-benzyl-aloohols, 106 Hydroxy-benzyl-methyl-ether, 122 Hydroxy-butyr-aldehyde, 133 Hydroxy-butyrio acid, 171, 172, 180, 239 Hydroxy-oaproio acid, 171, 180 Hydroxy-caprylic acid, 171 Hydroxy-cinnamic acid, 216, £j.9 Hydroxy-cinnamic-anhydride, 220 Hydroxy-citric acid, 171, 173 Hydroxy-crotonio acid, 171, 174 Hydroxy-decylio acid, 171 Hydroxj-erucic acid, 171 Hydroxy-ethyl, 81 Hydroxy-ethyl-amine, 321 Hydroxy-ethylium-hydrate, 356 Hydroxy-ethyl-methyl-piperideine, 399 Hydroxy-ethyl-Bulphonio acid, 291 Hydroxy-ethyl-tri-methyl-ammonium- hydroxide, 354 Hydroxy-formio acid, 179 HySroxy-glutaric acid, 171, 187 Hydroxy-hydro-muoonio acid, 171 Hydroxy-hydro-quinone-methyl- ether, 121 Hydroxy-hypogseic acid, 171 Hydroxy-itaconic acid, 171, 174 Hydroxyl, 65 Hydroxyl-amine, 318 Hydroxyl-amine chloride, 318 Hydroxyl, position of, 101, 146, 153, 183, 188, 462 Hydroxy-malonic acid, 186 Hydroxy-margaric acid, 171, 180 Hydroxy-methyl, 81 Hydroxy-methyl-tetra-hydro- quiuoline, 409 Hydroxy-methyl-tetra-hydro- quinoline-carboxylic acid, 409 Hydroxy-myristib acid, 171 Hydroxy-naphthoic acid, 226 Hydroxy-nonylic acid, 171 Hydroxy-oenanthylie acid, 171 Hydroxy-pahnitic acid, 171 Hydroxy-phenyl-alanine, 327 Hydroxy-phenyl-amido-propionic acid, 327 Hydroxy-propionic acid, 171, 179 Hydroxy-pyrotartaric acid, 187 Hydroxy-quinol, 93 Hydroxy-quinol-carboxylio acid, 221 Hydroxy-quinoMne, 366, 405 Hydroxy-stearic acid, 171, 180 Hydroxy-suberic acid, 171 Hydroxy-succinic acid, 186 Hydroxy-toluic acids, 223 Hydroxy-valerio acid, 171, 180 Hyoaoine, 400 Hyoacyamine, 400 Hyoscyn, 400 Hypnal, 345 Hypnon, 140 Hypo-chlorous acid, 485 Hypo-chloroiis anhydride, 485 Hypogseic acid, 171, 191 Hypo-iodous acid, 271, 485 Hypo-nitrous acid, 301, 486 Hypo-phosphoric acid, 488 Hypo-phosphorous acid, 487 Hypo-sulphurous acid, 439 Hypoxanthine, 377, 441 Hystazarin, 146 ICHTTOIi, 295 Ichtyolum germanicnm, 295 Idryl, 60 Imide, 384 ImidQ-hases, 814 Imido-ethyl-alcohol, 321 Imido-gronp, 814 Imines, 359 Immunity, 441 Inactive ethylidene-lactie acid, 179 Inactive valeric acid, 176 Indene, 30 Index of — acids, 165 alcohols, 67 aldehydes, 130 bonds in closed chains, 48, 218 bonds in open chains, 36 carbon-atoms in acids, 167 carbon-atoms in anthracene, 59, 60, 141 carbon-atoms in benzene, 42, 43 carbon-atoms in naphthalene, 31 carbon-atoms in open chains, 36, 167 carbon-atoms in penta- methylene, 26 carbon-atoms in pyrazol, 386 carbon-atoms in pyridine, 359 carbon-atoms in pyrone, 260 carbon-atoms in pyrrol, 386 carbon-atoms in quinoline,404,405 carbon-atoms in terpenes, 48 carbon-atoms in tetra- methylene, 25 carbon-atoms in tri-methylene, 25 phenols, 67 Index to aUphatio acids, 171 ludiarubber, 52 Indigo, 309, 365 Indigo-white, 365 Indole, 352 ludoxyl, 365 Induline, 335 Inosite, 94 Intramolecular anhydride, 182 Intramolecular change, 40 InuUn, 151 Invertase, 445 Invertin, 445 Invert-sugar, 157 Iodine, 265 Iodine-absorption, 242 lodo-acet-anilide, 342 lodo-antifebrine, 342 lodo-ethylene, 268 Iodoform, 266 lodol, 330 lodonium hydroxide, 485 lodo-pheniue, 349 lodo-pyrine, 344 lodo-salioyl-iodide, 271 lodoso-compounds, 271, 485 lodous acid, 271, 485 Ions, 280 Isatic acid, 364, 365 Isatin, 364 Isethionic acid, 291 Iso-aconitic acid, 196 Iso-alizarin, 146 Iso-allyl, 34 Iso-allylene, 37 Iso-allyleue-tetra-carboxylic acid, 173 Iso-amyl-amine, 441 INDEX 501 Iso-amylene, 36 Iso-amyl-iso-valerate, 232 Iso-amyl-nitrite, 304 Iso-anthraflavie aoid, 147 Iso-antipyiine, 344 Iso-apiol, 121 Iso-butane, 18 Iso-butenyl, 82 Iso-butyl, 11, 82 Iso-butyl-aoetio aoid, 177 Iso-butyl-oarbinol, 71 Iso-butyl-eresol, 97 Iso-butyl-oresol-iodide, 270 Iso-butylene, 36 Iso-bntylens-glyeol, 77 Iso-butyl-formio acid, 176- lao-butyl-nitrite, 303 Iso-butyrio acid, 176 Iso-cholesterin, 90 Iso-orotonic acid, 190 Jso-crotonyl, 83, 82 Iso-oyanides, 420 Iso-cyanogen, 419 Iso-cyanuric acid, 423 Iso-dialurio acid, 873, 376 lao-di-hydroxy-behenio acid, 171 Iso-eugeuol, 120 Iso-hexa-hydroxy-steario aoid, 198 Iso-hexane, 15 Iso-hydro-benzoin, 89 Iso-linolenio acid, 197, 198 Iso-Iinusic aoid, 183, 198 Iso-melamine, 424 Isomers, 12, 18 Isomers, optical, 49, 461 Isomers, stereometrical, 460 Isometamers, 13 Iso-nitriles, 420 Iso-nitroso-acetone, 303 Iso-nitroso-compounds, 802 Iso-oleic aoid, 192 Iso-oxazole, 387 Iso-palmitie aoid, 177 Iso-paraffins, 18 Iso-phthalic aoid, 217 Isoprene, 22, 89, 52 Iso-propenyl, 83, 82 Iso-propyl, 11, 82 Iso-propyl-acetic aoid, 176 Iso-propyl-aoetylene, 39 Iso-propyl-benzene, 44 Iso-propyl-ethylene, 20, 86, Iso-propylidene-ketone, 138 Iso-propyl-metliane, 13 Iso-pyrazoline, 386 Iso-pyrazolone, 386 Iso-quiaoliue, 390, 404 Iso-safrol, 121 laO-steario acid, 178 Iso-saccinic aoid, 18S Iso-terebentene, 50 Iso-terpene, 50 Iso-tri-hydroxy-stearic acid, 181 Iso -valeric acid, 176 Iso-valerylene, 22, 89 Iso-vanillin, 137 Itaconic aoid, 171, 174, 196 Itamalic acid, 187 Izal, 96 Jabobandinb, 395 Jaborine, 395 Jecoloio aoid, 171, 192, 193 Jecolein, 236 Jeyes' disinfectant, 96 Kairine, 409 Eairoline, 409 Eathions, 280 Kathode, 279 Kelen, 267 Kerasin, 485 Keratin, 436 Kerosene, 87 Ketone, 127, 138 Ketone-aoids, 207, 227 Ketone-aldehydes, 207, 230 Ketone, di-, 140 Ketone, dimethyl-, 188 Ketone, di-phenyl-, 141 Ketone, formation of, 127 Ketone, iso-propylidene-, 138 Ketone, methyl-ethyl-, 139 Ketone, methyl-phenyl-, 140 Ketone, mixed, 139 Ketoses, 151, 152 Ketoximes, 319 Kresin, 96 Lact-albumin, 432, 433 Lactames, 865 Lactic acids, 179 Lactic anhydride, 257 Laotide, 188, 257 Laotimes, 365 Lacto-biose, 157 Lacto-lactio aoid, 257 Lactones, 182 Laotonjc acid, 183 Laoto-phenine, 348 Lactose, 151, 155, 157 Lactyl, 201 Lffivo-Iaotio aoid, 180, 462, 463 Lsevo-tartaric aoid, 187, 464 Lanolin, 90 Lard, 288 Laurene, 52, 53 Laurie aoid, 171, 177 Lauronolio acid, 171 Law of atomic linking, 10 Law of limitation, 18 Lecithin, 434, 435 Legumin, 433 Lepargylic acid, 186 Leucaniline, 363 Leuceine, 326 Leuclo acid, 180 Leucine, 325, 826, 488 , Leuco-compounds, 860 Leuooline, 367 Leuoomaines, 440, 441 Leuco-malaohite-green, 360 Levulinio aoid, 228 Levulose, 151, 153, 426 Levulose-oarboxylio aoid, 426 Liebermann's reaction, 305 Lignooerio acid, 171, 178 Ligroin, 37 Limonene, 29, 50, 75 Linkage, 454 Linoleio aoid, 197 Linolein, 237 Linolenio aoid, 171, 198 - Linolenio acid, iso-, 198 Linolenin, 2-37 Linolio acid, 171, 198 Linolin, 237 Linseed oil, 238 Linusic acid, 171, 172, 183, 198 Linusio aoid, iso-, 183, 198 Lipoohromes, 436 Litmus, 96 Little's fluid, 96 Liver oils, 238 Losbphan, 269 Lupetidines, 397 Lupetidyl-alkins, 396 Lutidlnes, 398 Lysatine, 375 Lysatinine, 375 Lyaol, 96 Maodala-bed, 340 Malachite-green, 360, 492 Malakine, 349 Maleio acid, 171, 174, 195, 478 Maleio anhydride, 474 Maleinoid form, 219, 483 Malic aoid, 171, 172, 186, 478 Mallein, 442 Malonic acid, 168, 171, 184 Malonic ether, 242 Malonyl, 201 Malonyl-urea, 873 Malto-biose, 157 Maltose, 151, 157 Malt-sugar, 157 Mandelic acid, 218 Manna, 80 Mannite, 68, 80 Mannitol, 68, 80 Mannootite, 68 Manno-heptitol, 80 Mannonio acid, 183 Manno-sacobario acids, 188 Mannoses, 151, 153, 155 Margario aoid, 171, 177 Margarolio acid, 197 Marsh gas, 8 Matezite, 94 Mauveine, 840 Metonio aoid, 261 Meconine, 254 Meooninio acid, 254 Melamine, 423 Melauins, 436 Melanogen, 436 Helezitose, 151 Melibiose, 151 Melinite, 308 Melissyl-palmitate, 232 Melitose, 158 Melitriose, 158 Melliteue, 46 Mellitio acid, 222 502 INDEX Menhaden-oil, 238 Menthene, 49 Menthol, 98 Menthone, 143 Meicaptans, 281 Mercaptides, 881 Mercuric chloride, 267 Mercurous thio-oyanate, 424 Meroury-ethyl-ohloride, 267 Mereury-formamide, 328 Mercury-succiniinide, 329 Mercury- thymol- acetate, 175 Meaaconio acid, 195 Mesitene-alcohol, 87 Mesitonic acid, 171 Mesitylene, 45, 139 Mesitylene-glycol, 87 Mesitylic alcohol, 87 Meail^l-oxide, 138 Meso-para£fins, 18 Meso-tartaric aoid, 187, 464 Mesoxalio acid, 171, 187, 375 Mesoxaluric acid, 373 Mesoxalyl-urea, 373 Meta-, 43 Metamers, 13 Meta-phosphoric acid, 487 Meta-saccbarinic acid, 172 Methacetine, 347 Methacrylic acid, 190 Methane, 7, 12 Methane-derivatee, 7 Methanilide, 342 Methenyl, 11, 82 Methenyl-amidine, 331 Methoxy-, 81 Methoxy-acetio acid, 250 Methoxy-benz-aldehyde, 136 Methoxy-benzoic acid, 251 Methoxy-caffeiine, 379 Methoxyl, 81 Methoxy-phenyl, 116 Methoxy-quinoline, 406 Methoxy-tetra-hydro-quincline, 408 Methyl, 10, 14, 81, 82 Methyl-aoet-anilide, 342 Methyl-acetate, 207, 231 Methyl-acetylene, 39 Methylal, 114 Methyl-alcohol, 69 Methyl-aldehyde, 130 Methyl-allene, 20, 37 Methyl-amido-acetic acid, 356 Methyl-amido-phenate, 346 Methyl-amine, 313 Methyl-aniline, 314 Methyl-aurin, 108 Methyl-benzene, 44 Methyl-bromide, 265 Methyl-butyl-acetic acid, 426 Methyl-oarbamine, 420 Methyl-carbyl-amine, 420 Methyl-chloride, 265 Methyl-chloroform, 267 Methyl-cyanide, 420, 425 Methyl-di-acetylene, 22 Methyl-di-aUyl-carbinol, 75 Methyl-di-ethyl-methane, 15 Methyl-di-sulphonic acid, 291 Methylene, 11, 14, 82 Methylene-blue, 353 Methylene-bromide, 265 Methylene-chloride, 265 Methylene-di-ethyl-ether, 115 Methylene-di-methyl-ether, 114 Methylene-glycol, 76, 114 Methylene-iodide, 265 Methyl-ether, 113 Methyl-ether-protooatechuio acid, 252 Methyl-ethyl-acetal, 115 Methyl-ethyl-acetic aoid, 190 Methyl-ethyl-acetylene, 22 Methyl-ethyl-benzene, 45 Methyl-ethyl-ether, 113 Methyl-ethyl-ethylene, 20, 36 Methyl-ethyl-iso-hexyl-methane, 17 Methyl-ethyl-ketone, 139 Methyl-formate, 231 Methyl-glyeocoU, 324 Methyl-glyoo-oyamidine, 375 Methyl-glyco-cyamine, 374 Methyl-glyoollio aoid, 207, 250 Methyl-green, 47 Methyl-guanidine, 374, 440 Methyl-guanidine acetic acid, 374 Methyl - hexa - methylene - methyl - carbinol, 84 Methyl-hezyl-carbinol, 194 Methyl-hydro-sulphide, 281 Methyl-hydroxy-ethylium-hydrate, 356 Methyl-hydroxy-glubaric acid, 171 Methyl-hydroxy-valeric acid, 180 MethyUdene, 11, 82 Methyl-indole, 352 Methyl-iodide, 265 Methyl-iso-butyl-benzene, 45 Methyl-iso-cyanide, 420 Methyl-iso-propyl-benzene, 29, 45 ' Methyl-iso-propyl-benzene- di-hydride, 29 Methyl-iso-propyl-carbinol, 71 Methyl - iso-propyl - pseudo - pentyl - methane, 17 Methyl-mercaptan, 281 Methyl-methylene-gaUic acid, 412 Methyl-orange, 337 Methyl-penta-methylene-methyl- oarbinol, 83 Methyl-phenacetine, 348 Methyl-phenyl-oarbinol, 85 Methyl-phenyl-ether, 116 Methyl-phenyl-hydrazine, 333 Meihyl-phenyl-ketone, 140 Metbyl-piperideine, 398 Methyl-propyl-carbinol, 71 Methyl-protocatechuic aldehyde, 136 Methyl-quinoline, 405 Methyl-salicylate, 244 Methyl-saUcylic aoid, 245 Methyl-salol, 246 Methyl-succinic acid, 185 Methyl-sulphide, 281 Methyl-sulphone, 289 Methyl-Bulphonic acid, 289, 291 Methyl-tetra-aoetylene, 41 Methyl-tetra-hydro-quinoline, 409 Methyl-tri-ethylene, 21 Methyl-tri-methylene, 25 Methyl-tri-sulphonic acid, 291 Methyl-uramine, 374 Methyl-violet, 363 Metol, 358 Metozine-, 343 Miazines, 389 Migrainine, 379 Milk-sugar, 157 Mixed azo-compounds, 336 Molecular refraction, 144 Molecular weight, 4 Molecular weight, determination of, 279 Molecules, 2 Molecules, size of, 451 Monaeetin, 233, 234 . Monacid alcohols, 67, 69 Monacid phenols, 92 Monads, 3 Monamines, 313 Monatomio alcohols, 68 Monimines, 359 Mono-chlor-acetic acid, 273 Mono-chlor-ethylene-chloride, 266 Mono-chlor-ethylidene-chloride, 266, 267 Mono-ohloro-methane, 265 Mono-glycerides, 233 Mono-saccharides, 152, 153 Monoses, 151, 152 Mono-siUpho-benzoic acid, 295 Monovalent radicals, 10 Monureides, 872 Morphine, 416 Morpholine, 390, 416 Morrhuine, 441 Mucedin, 433 Mucic acid, 188 Mucins, 435 Mureiide, 375 Muscarine, 355, 440 Muscle-albumin, 432 Musk, artificial, 307 Mustard-oils, 424 Mycophylaxines, 442 Mycosozines, 442 Myoglobulin, 433 Myosin, 432, 445 Myosin-ferment, 432, 445 Myosinogen, 432 Myosinoses, 438 Myricyl-palmitate, 232 Myristio acid, 171, 177 Myrosin, 424, 446 Mytilotozine, 440 Nanoeio Aon>, 179 Naphtha, 37 Naphthalene, 31, 32 Naphthalene-sulphonic acid, 294 Naphthalol, 248 Naphthenes, 26 Naphthionic acid, 350 Naphthol, 103 Naphthol-benzoate, 249 Naphthol-oarboxylio acid, 226 Naphthol-salicylate, 248 Naphthol-salol, 248 Naphthol-sulphonio acid, 294 INDEX 503 Naphtho-quinol, 104 Naphthyl-amine, 350 Narcotine, 411, 413 NasTol, 379 Neo-para£Siig, 18 Neuiidine, 357, 440 Neurine, 354, 440 Neurodine, 371 Nicotine, 397 Nicotinic acid, 393 Nitric acid, 306, 486 Nitric-anhydride, 486 Nitric oxide, 486 Nitric peroxide, 486 NitrUe, 315, 420 Nitrile-bases, 315 Nitrile of dextrose-carbonic acid, 426. Nitrile of leyulose-carbonic acid, 426 Nitro-benzene, 306 Nitro-carbol, 304 Nitro-carbon, 304 Nitro-cellulose, 311 Nitro-chloroform, 305 Nitro-eompounds, 304 Nitroform, 304 Nitrogen-compounds, 301 Nitro-glycerin, 310 Nitro-group, 304 Nitrolic acid, 305 Nitro-methane, 304 Nitro-phenyl-aoetylene, 308 Nitro-phenyl-propioUo acid, 308 Nitroso-benzoyl-hydrazine, 383 Nitroso-oompounds, 302 Nitro-sulpho-iso-butyl-xylene, 307 Nitrosyl, 301, 302 Nitrous acid, 302, 486 Nitrous anhydride, 486 Nitrous oxide, 486 Nomenclature, future of — acids, 202 acid-amides, 331 acid-anhydrides, 262 alcohols, 109 aldehyde-acids, 261 aldehyde-ammonias, 322 aldehydes, 161 amides, 331 amidines, 331 amido-acids, 327 ammonia-bases, 315 ammonium bases, 316 azo-compounds, 338 carbohydrates, 161 compound ethers, 261 cyanogen-derivatives, 427 diamines, 317 diazo-compounds, 338 ether-acids, 261 ethers, 124 guauidines, 379 halogen-compounds, 274 hydramines, 322 hydrazine-compoimds, 334 hydrazo-compounds, 333 hydrazones, 340 hydrocarbons, 61 hydroxyl-amines, 320 iso-nitroso-compounds, 320 Nomenclature, future of (cont.) — ketone-aoids, 261 ketones, 161 nitro-compounds, 311 osazones, 340 oximes, 320 poly-amines, 317 sulphur-compounds, 298 ureas, 379 Non-acid alcohol, 68 Nonadecylene, 37 Nonane, 9, 12 NondecyUc acid, 171 Nonose, 151 Nonylenio acid, 171 NucloL, condensed, 30 Nucleic acid, 433 Nuclein, 438 Nuclein, 442 Nucleo-albumins, 433 Oak-tannic acid, 229 Oct-acid alcohols, 68 Octadeoane, 9 Octadeoa-tri-ethylene, 38 Octadeeatylidene, 38 Oetadecylene, 37 Octa-hydroxy-margaric acid, 171, 172, 184 Octane, 9, 12 Octoue, 41 Ootoses, 151 Odol, 368 CBnanth-ether, 232 CEnanthol, 132 (Enanthylic acid, 171 CBnauthylidene, 39 Oiazines, 389 Oil, lubricating, 37 Oil of bitter ahnonds, 134 Oil of cloves, 119 Oil of geranium, 74 Oil of sassafras, 120 Oil of turpentine, 52 Olefines, 20, 35 Olefines, derivatives, 27, 35 Olefines, formation of, 19 Olefines, isomers, 20, 36 Olefines, normal, 20, 35 Olefines, specification of, 35 Oleic acid, 171, 192 Oleic acid, iso-, 192 Olein, 236 Oleo-creasote, 244 Oleo-guaiacol, 244 Oleo-margaria, 238 Oleo-pahnito-butyrin, 234 Oleum anisi, 117 Oleum foeniculi, 117 Oleum pimpiuellsB, 117 Olive-oil, 238 Opianic acid, 253 Oroin, 96 Oroinol, 96, Orexine, 418 Orthine, 381 Ortho-, 43 Ortho-hydrazine-para-hydroxy- beuzoic acid, 381 Osazones, 154, 333 Osmotic pressure, 279 Osones, 155 Oso-tetrazone, 389 Oso-triazole, 387 Ossein, 436 Ovo-vitelUn, 433 Oxal-aldehyde, 132 Oxalic acid, 167, 171, 184 Oxaluric acid, 372 Oxalyl, 201 Oxamic acid, 328 Oxamide, 328 Oxanthranol, 141 Oxazlne, 390 Oxazole, 387 OxazoUne, 387 Oxethyl-acet-amido-quinoline, 407 Oxethyl-benzoyl-amido-quinoline, 407 Oxethyl-methyl-phenyl-pyrazolone,344 Oxunes, 302, 303, 319 Oximes, stereo-isomers, 320 Oxindole, 364 Oxy- (see also Hydroxy-) Oxy-aoanthine, 416 Oxy-alkyl, 81 Oxy-oarbanil, 342 Oxy-di-thio-oarbonic acid, 283 Oxy-ethyl, 81 Oxygen, 3, 65 Oxygen- and nitrogen-compounds, 301 Oxygen- and sulphur-compounds, 287 Oxygen-derivatives, 65 Oxy-hsBmoglobin, 436 Oxy-hydro-quinbne, 93 Oxy-hydro-quinone-methyl-ether, 121 Oxy-methyl, 81 Oxy-methyl-acet-aniUde, 347 Oxy-methyl-acetio acid, 250 Oxy-naphthoic acid, 226 Oxy-neurine, 355 Oxy-propylene-di-iso-amyl-amine, 353 Oxy-quin-aseptol, 407 Oxy-quinoline, 405 Oxy-sulphine, 287 Ozokerit, 37 Palmitic acid, 171, 177 Palmitic acid, iso-, 177 Palmitin, 235 Palmitolic acid, 171, 199 Palm oil, 235, 238 Pancreatic juice, 444 Pancreatin, 444 Papain, 444 Papaverine, 418 Papayrotin, 444 Paper, 158 Paper, Chinese, 158 Paper, Japanese, 158 Paper, parchment, 153 Para-, 43 Parabanic acid, 372 Para-chloralose, 272 Para-cholesterin, 90 Paraffin candles, 37 ParafBnic acid, 178 Paraffin, iso-, 12 Paraffin, meso-, 13 504 INDEX Paraffin, neo-, 18 Paraffin, normal, 7 Paraffin-oil, 37 Paraffin-series, 7 Paraformio aldehyde, 131 Para-fuohsine, 362, 492 Para-globulin, 432 Para-gluconio acid, 183 Para-lactio acid, 180 Paraldehyde, 131 Para-leuoaniline, 361 ParaUyl-anisoia, 117 Para-myosinogen, 433 Para-rosaniline, 361 Para-thi-aidehyde, 282 Fara-xanthine, 441 Parodyne, 343 Parvolines, 393, 440 Path, mean free, 451 Pearson's Creolin, 96 Pelargonic acid, 171 Pelletierine, 403 Penta-bromo-phenol, 271 Penta-ohlor-ethane, 267 Pentaoid alcohols, 68, 79 Fentacid phenols, 94 Pentacosane, 9 Penta-hydroxy-hexa-methylene, 210 Pental, 20, 36 Penta-methylene, 26 Penta-methyleftie-carboxylic acid, 210 Penta-methylene-diamine, 357, 425 Pentane, 9, 12, 14, 17, 23 Pentane-tri-oarboxylio acid, 171 Pentaphane, 26 Pentapheue, 28 Penta-thionic acid, 490, 491 Pentatriacontane, 10 Pentene, .35 Penthiophene, 286 Pentoses, 151 Pentoxazoline, 390 Pentyl, 10 Pentyl-alcohol, 70 Pentylene, 35 Pentyl-malonio acid, 186 Pepsin, 444 Pepsinogen, 444 Peptones, 437 Perehlor-ethane, 267 Perchloric acid, 485 Peroxide of hydrogen, 66 Petroleum, 37 Petroleum-ether, 87 Petroleum-naphtha, 37 Pharaoh's serpent, 424 Phaseo-mannite, 94 PheUandrene, 52 Phenaoetine, 348 Phenantrene, 31 Phenazine, 340 Phenazone, 343 Phenetidine, 346, 348 Phenetoa, 117 Phenetol, 117 Phenetol-carbamide, 347 Phenocol, 348 Phenol, 91, 92 Phenol-alcohol, 106 Phenol alcohol-ethers, 116, 123 Phenol-aldehyde, 135 Phenol-aldehyde-ether, 136 Phenol, allyl-, 100 Phenol, anthracene-, 101 Pheuolates, 109 Phenol, benzene-, 92 Phenol, benzene-ethylene-, 100 Phenol, cymene-, 97 Phenol-ethers, 116, 118 Phenol- glyeollic acid, 251 Phenolide, 341 Phenoline, 96 Phenol, naphthalene-, 103 Phenol-oxy-quinolLne-sulphonate, 407 Pheuol-phtalein, 224 Phenol-sulphonio acid, 292 Phenol, terpene-, 97 Phenol, toluene-, 95 Phenones, 140 Phenosalyl, 216 Phenyl, 34 Phenyl-acet-amide, 341 Phenyl-acetate, 243 Phenyl-acetic acid, 207, 212 Phenyl-aoetylene, 55 Phenyl-acrolein, 134 Phenyl-aoryhc acid, 214 Phenyl-aloohol-ethers, 116, 122 Phenyl-aldehyde-ether, 136 Phenyl-allyl, 47 Phenyl-aUyl-aleohol, 90 Phenyl-amine, 313 Phenyl-ahisate, 247 Phenyl-benzene, 57 Phenyl-benzyl-oarbinol, 88 Phenyl-cresotate, 246 Phenyl-di-hydro-quinazoline, 418 Phenyl-di-methyl-pyrazolone, 343 Pheuyl-di-phenol-oarbinol, 107 Phenyl-di-sulphide, 281 Phenylene, 34 Phenylene-di-amine, 317 Phenylene-di-amine-brown, 335 Phenyl-ethers, 116 Phenyl-ethylenes, 47 Phenyl-glycerol, 86 Phenyl-glycol, 85 Phenyl-glyooUic acid, 213 Phenyl-glyoxylio acid, 213 Phenyl-hydracrylic acid, 214 Phenyl-hydrazine, 154, 332 Phenyl-hydrazine-levulinio acid, 339 Phenyl-hydroxy-propyl-methyl- amine, 314 Phenyl-mercaptans, 281 Phenyl, methoxy-, 116 Phenyl-methyl-iso-pyrazolone, 344 Phenyl-methyl-pyrazolidone, 382 Phenyl-methyl-pyrazolone, 382 Phenyl-oxy-acetic acid, 251 Phenyl-paraffins, 44 Phenyl-penta-methylene, 56 Phenyl-propiolic acid, 215 Phenyl-propionic acid, 212, 213 Phenyl-propyl-alcohol, 84 Phenyl-propylene, 47 Phenyl-salicylate, 245 Phenyl-salieylio acid, 246 Phenyl-sulphides, 281 Phenyl-sulphonic acid, 292 Phenyl-sulphuric acid, 297 Phenyl-urea, 371 Phenyl-urethane, 370 Phloroglucin, 93 Phloroglncin-oarboxylic acid, 221 Phoeenic acid, 176 Phorone, 139 Phosgene, 273 Phosphoretted hydrogen, 487 Phosphoric acid, 434, 487 Phosphoric anhydride, 488 Phosphorous acid, 487 Phosphorous anhydride, 488 Phosphorus, 487 Phosphorus-compounds, 434 Photogen, 37 Photographic developers, 357 Phthaleine-group, 224, 860 PhthaUo acid, 217 PhthaUo anhydride, 217 Phthalyl-alcohol, 87 Phylaxines, 442 Phyllooyanine, 486 Phylloxanthine, 436 Phylloxera-killer, 283 Physetoleic acid, 191 Phyt-albumose, 433 Phytosterin, 90 PhytoviteUin, 433 Piazines, 389 Picene, 31 Picoline, 392, 393 Picolinic acid, 393 Pioolyl-methyl-alkine, 398 Picric acid, 808 Picrol, 298 Pilocarpio acid, 395 Pilocarpidine, 394 Pilocarpine, 395 Pilou, 311 Pimelio acid, 171, 185 Pinaeone, 77 Pinene, 51 Pinite, 94 Pipecolines, 397 Piperazidine, 358 Piperazine, 358 Piperio acid, 221 Fiperideme, 398 Piperidine, 859, 396 Fiperidyl-ethyl-alkine, 396 'Fiperine, 397 Piperonal, 137 Fiperylene, 28, 38 Firylene, 21, 38 Pixol, 96 Plane-symmetrical form, 483 Plasma-globulin, 432 Plus-sugar, 158 Po-ho-yo, 98 Poly-amines, 317, 360 Foly-ethylene-derivatives, 30 Foly-hexoses, 151 Polymerisation, 32 Poly-saccharides, 151 Polysolve, 296 Poppy-oil, 288 INDEX 505 Porpoise-oil, 238 Position, favoured, 460 Potassium-acetate, 240 Potassium-aoetyl-hydroxy- butyrate, 240 Potassium-ferri-oyanide, 420 Potassium-ferro-oyanide, 420 Potassium-hydroxy-butyrate, 240 . Potassium-myronate, 424 Potassium-phenol-sulphonate, 298 Potassium-salt, 240 Primary alcohols, 69 Primary bases, 313 Propane, 8, 12 Propargyl, 34, 82 Propargyl-alcohol, 75 Propargylio acid, 174, 199 Propargyl-penta-carboxylio acid, 173 Propene, 35 Propenyl, 33, 82 Propenyl-alcohol, 73 Propenyl-phenol, 101 Propinyl, 34, 82 Propiolio acid, 171, 174, 199 Propionic acid, 168, 171, 176, 462 Propionyl, 200 Propyl, 10, 82 Propyl-acetylene, 22, 39 Propyl-alcohol, 70 Propyl-amine, 313, 440 Propyl-benzene, 44 Propylene, 35 Propylene-glycol, 77 Propyl-ethylene, 36 Propylidene, 11, 82 Propyl-nitrolio acid, 305 Propyl-piperidine, 396 Propyl-pseudo-nitrol, 305 Propyl-pyridine, 392 Prosthetic groups, 433 Frotagons, 435 Protads, 431 Proteids, compound, 433 Proteids, disintegration of, 439 Proteids, protective, 442 Proteoses, 437 Pxoto-albumoses, 437 Proto-catechuic acid, 219 Proto-catechnic alcohol, 106 Proto-oateohuic aldehyde, 136 Proto-catechuic aldehyde- methylene-ether, 137 Prussian-blue, 420 Prussiate, red, 420 Prussiate, yellow, 420 Pseudo-aconitic acid, 196 Pseudo-butylene, 36 Pseudo-carbostyril, 366 Pseudo-cnmene, 45 Pseudo-eumylene-alcohol, 88 Pseudo-ephedrine, 314 Pseudo-nitrols, 306 Pseudo-pentane, 14 Pseudo-xanthine, 441 Ptomaines, 440 Ptyalin, 444 Ptyalinogen, 444 Purpuric acid, 375 Purpurin, 147 Purpur-oxanthin, 146 Putrescine, 357, 440 Py-, 405 Pyoktannin, 363 Pyrazine, 386, 389 Pyrazol, 386 Pyrazolidine, 386 Pyrazolidone, 386 Pyrazoline, 386 Pyrazolone, 386 Pyrene, 60 Pyridine, 859, 388, 391, 393 Pyridine-carboxylic acid, 393 Pyridine compounds, 391 Pyrldine-di-carboxylic acid, 394 Pyridine, hydrated, 395 Pyridine-lactio acid, 394 Pyrimidine, 389 Pyro-oatechin, 92 Pyrodine, 380 Pyrodinum angUcum, 380 Pyro-gallic acid, 93 Pyro-gallol, 98 Pyro-gallol-carboxylic acid, 221 Pyro-glyoerin, 116 Pyro-mucic acid, 260 Pyrone, 260 Pyro-phosphoric acid, 488 Pyro-racemic acid, 227 Pyro-tartario acid, 171, 185 Pyro-terebic acid, 171 Pyroxylin, 311 Pyrrol, 329, 386 Pyrrolidine, 386 Pyrrolidone, 386 Pyrroline, 386 QXTABIEBNAIiY BASES, 316 Quercite, 94 Quercitannic acid, 229 Quinaldine, 405 Quinaldinic acid, 406 Quinanisol, 406 Quinazine, 390 Quinazoline, 390 Quinic acid, 210 Quinidine, 411 Quinine, 411 Quininic acid, 406 Quinizarin, 146 Quinizarin-hydrate, 107 Quino-iodine, 408 Quinolidine, 406 Quinoline, 367, 390, 404 Quinoline-earboxylic acid, 406 Quinoline-derivatives, 404 Quinolinic acid, 394 Quinone, 139, 142 Quino-phenol, 405 Quinoxaline, 390 BACEMI3 ACID, 187 Eadicals, 10, 33, 81, 200 Radicles, 10 Eaffinose, 151, 168, BafiSnose-group, 161 Eaoult's law, 279 Bape-oil, 238 Bed prussiate, 420 Bennet, 445 Beplacement, 7 Besidues, 10 Besinol, 52 Resorcin, 92 Bests, 10 Betinol, 52 Bhamnitol, 80 Bhigolene, 37 Bhodallin, 371 Bhodanides, 424 Ehodinol, 74 Bichardson's caustic, 109 Bicin, 441 Biciuelaidic acid, 195 Eicinisolic acid, 195 Bicinoleic acid, 171, 194 Bicinolein, 236 Eicinolic acid, 195 Eing formation, 24, 458 Eoeoellio acid, 171 Eodinal, 367 Bosaniline, 361, 362 Eosaniline group, 360 Eosaurin, 108 Bosinol, 52 Eosolic acid, 108, 492 Bosolic acid-group, 108, 360 Bubidines, 393 Bufol, 101 Sacchabic acid, 171, 172, 188 Sacchariii, 182 Saccharine, 368 Saccharinic acid, 171, 181 Saccharose, 151, 166 Safranines, 340 Safrol, 120 Salacetol, 246 SaJ-ammoniac, 323 Salbromalide, 342 Salicin, 160, 446 Salicyl, 201 Salicyl-aldehyde-phenetidine, 349 Salicyl-aniUde, 346 Salicyl-brom-anilide, 342 Salicylic acid, 215 Salicylic alcohol, 106 SalicyUc aldehyde, 135 SaUcyUde, 258 Salicylide-chloroform, 258 Salicyl-methyl-phenyl-hydrazone, 338 Salicyl-tolyl-di-methyl-pyrazolone, 344 SaUgenin, 106 Salinaphthol, 248 Saliphene, 349 Salipyrine, 345 Salocol, 348 Salol, 246 Salophene, 343 Salt of sorrel, 184 Saltpetre-ether, 303 Samandarine, 441 Santonin, 225, 226, 492 Santoninic acid, 224, 225, 226 Sapokarbol, 96 L L 506 INDEX Saponification, 233 Saponification-valae, 241 Saprine, 440 Saprol, 96 Sarcine, 377, 441 Saico-laeUc acid, 180 Saicosine, 324, 356 Sardine-oil, 238 Sativic acid, 171, 183 Saturated aliphatic acids, 169, 175 Scopolamine, 400 Screw-theory, 462 Seal-oil, 238 Sebacic acid, 171, 186 Secondary alcohols, 69 Secondary bases, 314 Sedatine, 843, 347 Sennite, 94 Sequardin, 442 Sericin, 486 Serine, 325 Serum-albumin, 432 Serum-casein, 482 Serum-globulin, 432 Serum-luteiin, 436 Sesam-oil, 238 Silk, 436 Sinistrin, 151 Sinkaliae, 354 Skatole, 352 Skeletins, 436 Skraup's synthesis, 404 Snake-poisons, 441 Soaps, 238 Sodium-benzoate, 384 Sodium-ethylate, 109 Solar oil, 37 Solutol, 96 Solveol, 96 Solvin, 296 Somnal, 370 Sorbic acid, 171, 197 Sorbin, 152, 155 Sorbinose, 151, 155 Sorbite, 80 Sorbitol, 80 Sozal, 293 Sozines, 442 Sozoiodol, 293 Sozolic acid, 292 Spermaceti, 72 Spermatin, 436 Spermine, 358 Sperm-oil, 37 Spirit-blue, 47 Spirits of wine, 67, 70 Spiritus setheris nitrosi, 303 Spougin, 436 Stable structures, 454 Stachyose, 151, 158 Starch, 151, 158 States of aggregation, 277, 450 Steapsin, 445 Stearic acid, 171, 178 Stearic acid, iso-, 178 Stearin, 235 Stearolic acid, 171, 192, 199 Stearoxylic acid, 192, 200 Stereo-isomers, 461 Stsrnutament, 226" StUbene, 48 Stinking stone, 295 Stycerol, 86 Styracol, 248 Styrene, 47 Styrolene, 47 Styrolene-alcohol, 85 Styrolyl-alcohol, 84, 85 Styrone, 90 Suberic acid, 171, 186 Suberonic acid, 171 Substitution, 7 Succinamic acid, 328 Suooinamide, 328 Succinic acid, 171, 172, 185, 464 Succinic acid, iso-, 185 Succinic anhydride, 185 Succinimide, 329 Succinyl, 201 Sucrol, 347 Suet, 238 Sugar, cane-, 156 Sugar, malt-, 157 Sugar, milk-, 157 Sulph-amido-benzoic acid, 366 Sulphaminol, 353 Sulph-anilic acid, 367 Sulphides, 281 Sulphine, 286, 485 Sulphine-oxide, 287 Sulphinic acid, 287 Sulphite-cellulose, 158 Sulpho-acetic acid, 295 Sulpho-benzoic acid, 295 Sulpho-carbonic acid, 282 Sulphonal, 290 Sulphone, 289 Sulphonic acid, 289 Sulphonium, 485 Sulphonyl, 290 Sulphonyl-compoimds, 290 Sulpho-urea, 371 Sulpho-vinic acid, 296 Sulph-oxide, 287 Sulphur, 277, 488 Sulphur-compounds, 277 Sulphur-dioxide, 288, 489 Sulphuretted hydrogen, 280, 489 Sulphuric acid, 289, 296, 490 Sulphuric anhydride, 489 Sulphurous acid, 288, 289, 290, 489 Sulphurous anhydride, 288, 489 Sulphur-trioxide, 489 Sulphuryl, 289 Sweet spirits of wine, 303 Sylvestrene, 50, 456 Symmetrical position, 43 Symphorol, 379 Syn-acetaldoxime, 320 Syn-aldoxime, 320 Synaptase, 446 Syntonin, 437 Tannic acid, 228 Tannin, 255 Tarchonyl-alcohol, 72 Tartaric acid, 171, 172, 187, 464 Tartronic acid, 168, 171, 186. Tartronyl-urea, 373 Taurine, 367 Tauro-cholic acid, 367 Tautomerism, 93 Teracrylic acid, 171 Terebene, 52 Terebentene, 51 Terebentine, 51 Terecamphene, 51 Terephthalic acid, 217 Terpenes, 49 Terpenes, di-, 52 Terpenes, poly-, 52 Terpenes, sesqui-, 52 Terpine-hydrate, 98 Terpinene, 51, 52, 53 Terpineol, 98 Terpinolene, 50 Tertiary alcohols, 69 Tertiary bases, 315 Tetanine, 440 Tetanotoxine, 440 Tetra-acetylene, 23, 41 Tetra-acetylene-di-carboxylio acid, 17 1 Tetra-bromo-methane, 266 Tetra-bromo-phenol-bromide, 271 T«tra-chloro-methane, 265, 266 Tetraoid alcohols, 68, 79 Tetracid phenols, 94 Tetracosane, 9 Tetradecane, 9 Tetrads, 3 Tetrad sulphur-compounds, 286 Tetra-ethylene, 21, 38 Tetra-hydro-naphthyl-amine, 351 Tetra-hydro-oxazine, 390 Tetra-hydro-phthaUc acids, 219 Tetra-hydro-pyridine, 398 Tetra-hydro-quinoline, 408 Tetra-hydroxy-benzene, 94 Tetra-hydroxy-stearic acid, 171, 183 Tetra-iodo-methane, 266 Tetra-iodo-pyrrol, 330 Tetra - methyl - ammonium- hydroxide, 3] 6, 485 Tetra-methyl-carbinol, -72 Tetra-methyl-di-amido-tri - phenyl- carbinol-chloride, 861 Tetra-methyl-di-amido-tri - phenyl - methane, 860 Tetra-methylene, 25 Tetra-methylene-carboxylic acids, 208 Tetra-methylene-di-amine, 357 Tetra-methyl-ethane, 16 Tetra-methyl-methane, 14 Tetra-methyl-thionine-chloride, 353 Tetra-nitro-methane, 304 Tetra-phenyl-ethane, 47 Tetra-thionic acid, 490 Tetrazines, 389 Tetrazo-compounds, 337 Tetrazole, 387 Tetrolio acid, 171, 199 Tetronal, 290 Tetroses, 151, 152 Thalline, 408 Thebolactic acid, 179 Theobromio acid, 178 INDEX 507 Theobromine, 378 Therapio acid, 171, 198 Therapin, 237 Thennifugine, 409 Thermine, 351 Thermodine, 371 Thi-aldehyde, 282 Thialdine, 322 Thilanin, 296 Thio-acetio aoid, 282 Thio-aoids, 282 Thio-aleohols, 281 Thio-aldehydes, 282 Thio-benzoio acid, 283 Thiooamf, 144 Thio-oarbamide, 371 Thio-oompounds, 280 Thio-cyanic acid, 424 Thio-dl-phenylamine, 352 Thio-ethers, 281 Thioform, 285 Tbio-bydroxy-benzoic acid, 284 Tbio-bydroxy-di-pbenyl-amine, 353 Tbiol,.295 Thiolin, 296 Thiols, 281 Thiophene, 285 Tbiopbene-di-iodide, 283 Tbio-pbenols, 281 Tbio-salicylio acid, 283 Thiosiuamine, 371 Thio-sulpburic aoid, 490 Thio-urea, 371 Thioxy-carbonic acid, 282 Thymaoetine, 850 Thymol, 97 Tbymolol, 270 Tiglio acid, 191 Tobacco-smoke, 397 Tolane, 55 Toluene, 44 Toluene-tetra-hydride, 28 Tolu-hydro-qulnone, 96 Toluio acid, 223 Toluidine, 313 Toluquinol, 96 Toluquinobne, 405 Toluyl, 201 Toluylene, 48 Toluylene-hydrate, 88 Toluylio acid, 212 Tolyl, 34 Tolyl-carbinol, 86 Tolyl-di-methyl-pyrazolone, 344 Tolylene-glycol, 87 Tolypyrine, 344 Tolysal, 344 Tonquinol, 307 Toiula urese, 446 Toxalbumins, 441 Toxins, 441 Toxo-globuMn, 441 Toxo-muoin, 441 Toxo-peptone, 441 Toxo-phylaxines, 442 Toxo-sozines, 442 Trans-, 219, 483 Transformation, spontaneous, 52 Trehalose, 151 Triaoetin, 233, 234 Tri-acetylenes, 23, 41 Triaoid alcohols, 67, 78 Triacid phenols, 93 Triads, 3 Tri-amido-tri-phenyl-metbane, 361 Triazinea, 389 Triazole, 387 Tri-bromo-hydrin, 268 Tri-bromo-pbenol, 269 Tri-bromo-propane, 268 Tri-carbaUylic acid, 171, 173, 188 Tri-chlor-acetic acid, 273 Tri-ohlor-acetyl-chloride, 273 Tri-ohlor-aldehyde, 271 Tri-chlor-ethane, 267 Tri-chlor-ethidene-hydroxy-amine, 368 Tri-ohloro-butyr-aldehyde, 272 Tri-chloro-hydrin, 268 Tri-chloro-nitro-methaue, 305 Tri-chloro-phenol, 269 Tri-cbloro-propane, 268 Tri-ethoxyl-amine, 321 Tri-ethyl-amine, 315 Tri-ethylene, 21, 38 Tri-ethylene-eyclo-derivatives, 29 Tri-ethylene-di-amine, 359 Tri-etbylene-tri-amine, 317 Tri-ethyl-sulpbone-methyl- methane, 290 Tri-glycerides, 233 Tri-glyooUic acid, 171, 183 Tri-hexoses, 151, 158 Tri-hydroxy-aoetophenone, 145 Tri-hydroxy-adipio aoid, 171 Tri-hydroxy-stearic acid, 171, 181, 195 Tri-hydroxy-stearic acid, iso-, 181 Tri-imines, 359 Tri-iodo-oresol, 269 Tri-jecolein, 236 Trimellitic aoid, 219 Trimesic acid, 219 Tri-methyl-amine, 315, 440 Tri-methyl-benzene, 45 Tri-methyl-oarbinol, 70 Tri-methylene, 24 Tri-methylene-carboxylic acids, 208 Tri-methylene-cyanide, 425 Trl-methylene-diamine, 356 Tri-methylene-di-oarboxyUc acid, 196, 208 Tri-methyl-ethylene, 20, 36 Tri-methyl-ethyl-methane, 16 Tri-methyl-glycocoll, 355 Tri-methyl-hydroxy-ethylium- hydrate, 356 Tri-methyl-methane, 13 Tri-methyl-pyridine, 392 Tri-methyl-sulphine-hydroxide,286,485 Tri-methyl-sulphine-iodide, 286, 485 Tri-nitrin, 310 Tri-nitro-benzene, 307 Tri-nitro-butyl-toluol, 307 Tri-nitro-methane, 304 Tri-nitro-phenol, 308 Tri-nitro-propane, 310 Trional, 290 Trioses, 151, 158 Tri-oxy-methylene, 131 Tri-palmitin, 235 Tri-phenol-alcohols, 107 Tri-phenol-carbinol, 107, 492 Tri-phenyl-amine, 315 Tri-pheny] -benzene, 58 Tri-phenyl-oarbinol, 89 Tri-phenyl-methane, 47 Tri-rioinoleiin, 236 Tri-saccharides, 151, 158 Tri-stearin, 235 Tri-thio-carbonic acid, 282 Tri-thionio aoid, 490 Tropseolines, 335 Tropic aoid, 214 Tropine, 399 Trypsin, 444 Trypsinogen, 444 Tuberculin, 442 Tuberculinio acid, 442 Tuberculinose, 442 Tuberculocidin, 442 Tumenol, 296 Tumenol-sulphone, 296 Tumenol-sulphonic acid, 296 Tunioin, 158 Turnbull's blue, 420 Turpentine, artificial, 37 Turpentine, oil of, 52 Turpentine oils, 48 Typhotoxine, 440 Tyrosine, 327, 438 Tyrotoxioon, 337, 440 TJmbellio acid, 220 Umbelliferone, 220 XJndecane, 9 TJndecolic aoid, 171, 199 Undecylenio acid, 171, 191 Undeoylic acid, 171, 177 Unguentum paraffini, 37 Unsaturated aliphatic acids, 169 Unstable structures, 454 Ural, 370 Urea, 328, 371, 374, 422 Urea, alkylated, 371 Ureas, 371 Ureides, 371, 372 Urethane, 870 Uric acid, 376 Vaccines, 442 Valencies, 8 Valencies, changing, 280, 484 Valeric acids, 171, 176 Valeryl-amido-phenetol, 347 Valeryl, di-valent, 201 Valerylene, 22, 40 Valylene, 22, 28, 41 Vanillic acid, 252 Vanillic alcohol, 123 Vanillin, 186 Vanillin, artificial, 137 Vanillin, iso-, 137 Vaselin, 37 Vicinal position, 43 Victoria-green, 361 Vinyl, 88, 82 508 Vinyl- acetic acid, 190 Vinyl-alcohol, 73 Vinyl-benzene, 47 Vinyl-bromide, 268 Vinyl-chloride, 268 Vinyl-ethyl-carbinol, 73 Vinyl-ethylene, 21, 38 Vinyl-ethyl-ether, 114 Vinyl-iodide, 268 Vinyl-tri-methyl-ammonium- „. .,. hydroxide, 354 Viridines, 393 Vitellin, 433 Vitelloses, 438 Vortex hypothesis, 449 INDEX WAuroT-on,, 238 Water, 65 Weight, atomic, 3 Weight, molecular, 4 Whale-oil, 238 Wood-pulp, 158 Wood-spirits, 69 Xanthic Acm, 283 Xanthine, 376, 441 Xanthine-componnds, 375 Xantho-creatinine, 441 Xantho-pnrpnrin, 146 Xeronio acid, 171 Xylenes, 44 Xylitol, 80 Xylose, 151 Xylyl, 34 TEliOW-PBUSSIATE, 420 Zapon, 311 Zero, absolute, 449 Zymase, 445 Zyme, 444 Zymogen, 444 PRINTED Br SfOTHSWOODi AMD 00., NEW-BTBEET SQCARB LOXDOS