March 20, 1884] 



NA TURE 



491 



though the outcome of much of his subsequent work, or at lea.t 

 much of that which he did in concert with Liebig, might be said 

 to bring him in occasional conflict with Berzelius's cherished 

 convictions on points of chemical theory, the master and pupil 

 remained to the end bound together in the warmest friendship. 

 Scarcely a month passed without an exchange of letters. Those 

 from Berzelius were religiously preserved by Wohler, who, after 

 his master's death in 1S48, presented them, to the extent of some 

 hundreds, to the Swedish Academy of Sciences. We are told 

 that in the later letters the " trauliche Du" appears in place of 

 the more formal "Sie," and that " Tot us ct taut us tuns" is a 

 not unfrequent signature. 



Wcihler's gratitude and almost filial reverence are seen in the 

 circumstance that even in the full tide of his vigour, and when 

 time was doubly precious to him, he continued to charge himself 

 with the yearly translation of Berzelius's Jahresbaicht into 

 German. It is easy to trace the influence of \\'ohler's contact 

 with Berzelius in his after work. To begin with, tlie men had 

 much in common: their sympathies were as catholic as science 

 itself, and they ranged at \\ ill over every department of chemical 

 knowledge. Wohler attacked the composition of a mineral with 

 as much ardour as he did the preparation of an organic com- 

 pound : to liim the problems of physiological chemistry were not 

 more important than the isolation of a rare earth or the perfec- 

 tion of some analytical method. The artificial barriers and 

 fancied lines of demarcation in the science seemed to have no 

 existence for Wohler : indeed, it was the crowning triumph of 

 his work to break down such barriers almost at a stroke, and to 

 demonstrate the irrationality of these attempts to draw distinc- 

 tions i-egardless of differences. The history of chemistry is 

 indeed like that of the nation which has done so much to ad- 

 vance it : its unity to-day is as complete as that of Germany 

 itself. 



Wohler was now to embark on his academic career, and under 

 the advice of Gmelin and Tiedemann he prepared to se'tle in 

 Heidelberg as f rival doceiit. But to Heidelberg he was not 

 destined to go. His work had already been gauged by such 

 men as Leopold von Buch, PoggendorfT, and Mitscherlich, and 

 these, without his knowledge, had strongly recommended his 

 election to the vacant teachership of chemistry in the newly- 

 founded Trade School in Berlin. Berzelius advised him to 

 accept the post, and to Berlin accordingly Wohler went in 1825. 

 He was now in possession of a laboratory which he could call 

 his own, and he had to justify that possession by the use which 

 he made of it. One of the problems which he now attacked 

 was the isolation cf aluminium, a metallic radicle more abun- 

 dant and more widely diffused than any other of the fifty bodies 

 we are accustomed to designate as metals. He succeeded in 

 obtaining the body by the method which, nearly twenty years 

 after, was worked out on a manufacturing fcale by Sainte-Ciaire 

 Deville. Deville caused the first bar of the metal thus procured 

 to be struck as a medal, with the image of Napoleon III. on the 

 one side, and the name Wohler with the date 1827 on the other, and 

 some time after the Emperor simultaneously designated the two 

 chemists officers of the Legion of Honour. 



But of the twenty-tn o memoirs and papers which Poggendorff 's 

 Aiiuaic-H exhibits as the outcome of Wohler's aclivity and power of 

 work during his six years' stay in Berlin, that on the artificial for- 

 mation of urea is by far the most important. No single chemical 

 discovery of this century has exercised so great an influence on the 

 development of scientific thought, and the words "ith which 

 Wohler closes his account of the molecular transformation of am- 

 monium cyanate — a body of purely inorganic origin — into urea — a 

 substance whicli of all that might be named is the most characteris- 

 tic of the action of the so-called vital force — are full of mean- 

 ing : " This unexpected result," he says, " is a remarkable fact, 

 in so far as it presents an example of the artificial formation 

 of an organic body, and indeed one of animal origin, out of 

 inorganic materials." " The synthesis of urea," says Prof. 

 Hofmann in his account of Wohler's life-work, "was an 

 epoch-making discovery in the real sense of that word. With it 

 was opened out a new domain of investigation upon which the 

 chemist instantly seized. The present generation, which is con- 

 stantly gathering such rich harvests from the territory won for it 

 by Wohler, can only with difficuliy transport itself back to that 

 remote period in which the creation of an organic compound 

 within the body of a plant or an animal appeared to be con- 

 ditioned in some mysterious way by the vital force, and they can 

 hardly realise the impresssion which tlie building up of urea from 

 its elements then made upon men's mirds. And yet it cannot 



be said that chemists were unprepared for this discovery. Men 

 were long ago in the habit of perceiving that bodies of 

 mineral origin were but the types of those met with in the 

 animal and vegetable organism— in both classes there were the 

 same differences in states of aggregation, the same mutual trans- 

 formations, the same crystalline forms, the same constancy in 

 combining relations, the same conjunction of the elements 

 according to the weights of their atoms or in multiples of these, 

 in both classes the appearance of the same species of compounds. 

 But all attempts to build up organic compounds from their 

 elements, as this for a large number of mineral substances had 

 already been done, had hitherto been futile. The chemists of 

 that period had nevertheless the presentiment that even this 

 barrier must fall, and one can cmceive the feeling of joy with 

 which the gospel of a new unified chemistry was hailed by the 

 intellect of that time. With the revolution thus effected in the 

 ideas of men, science was directed into new paths and unto new 

 goals. Who does not kno.v with what zeal these paths have 

 been trodden, and how many of these goals have been 

 reached ! " 



But if at this time Wohler made a great discovery for the 

 world, he also, at about the same time, made a great discovery for 

 himself : he discovered Liebig. The manner in which the two 

 men were brought together is worth mentioning, for it would 

 seem almost as if the hand of destiny was in it. At about the 

 time that Wohler was at Stockholm thinking and working on 

 cyanic acid, Liebig was at Paris engaged with Gay Lussac on 

 the study of the metallic compounds of an acid which, on 

 account of their formidable explosive properties, has received 

 the not inappropriate name of fulojinic acid. Liebig, with rare 

 skill and courage, had determined the composition of that acid, 

 and had been rewarded by the honour of a waltz with Gay 

 Lussac, it being the habit of that disinguished philosopher, as 

 he explained to the astonished young German doctor, to express 

 his ecstasy on the o;casion of a new discovery in the poetry of 

 motion. But the most extraordinary result of tliat investigation 

 was to .show that the terribly explosive fuiminic acid and the 

 innocuous cyanic acid were of identical composition. The idea 

 that bodies could exist of identical ultimate compisition — that 

 is composed of the same elements united in the same proportion 

 and yet possess essentially different properties, in other words be 

 absolutely dissimilar things, was new to science ; Berzelius, the 

 great chejaical lawgiver of his time, sc rated the notion as 

 absurd ; to him it was impossible to conceive that identity in 

 elementary composition should not result in identity of proper- 

 ties. And yet, later on, Berzelius was forced to realise the fact 

 by the discovery by his pupil Wohler of the molecular transfor- 

 mation of ammonium cyanate into urea, and to coin for Us the 

 word isomerism, by which that fact is denoted. 



It was thus from the singular circumstance that Wohler and 

 Liebig were at the outset of their career engaged upon the 

 elucidation of the nature of two bodies of identical composition, 

 b-at of dissimilar origin, dissimilar relations, and very different 

 properties, that they were brought into juxtaposition. They 

 desired to know each other : they met in the house of a mutual 

 friend at Frankfort, and the names of Liebig and Wohler became 

 henceforth linked t gether for all time. 



The origin of that partnership, so fruitful in consequences for 

 science, may be seen in the following characteristic letter :— 



" Frederick Wohler to Justus Liebig 



" Sac row, near Potsdam, yuneS, 1829 



' ' Dear Professor, — The content of your last letter to Poggen- 

 dorff has been cim'iiunicated to me by him, and I am glad that 

 it aifiirds me an opportunity of resuming the correspondence 

 which we began last winter. It must surely be some wicked 

 demon that again and again imperceptibly brings us into ciUision 

 with our work, and tries to make the chemical public believe 

 that we purposely seek as opponents these apples of discord. 

 But I think he is not going to succeed. If you are so minded, 

 we might, for the humour of it, undertake some chemical work 

 together, in order that the result might be made known under 

 our joint names. Of course, you would work in Giessen, and I 

 in Berlin, after we nere agreed upon the plan, and had com- 

 municated with each other from time to time as to its progress. 

 I leave the choice of subject entirely to you. 



" I am very glad that you liave also determined the identity of 

 pyrouric acid, and cyanic [cyanuric] acids. L. Gmelin would 

 say ; ' God be thanked, there is one acid the less ! ' 



' Yours, 



' WiiHLER " 



