492 



NA TURE 



[March 20, 1884 



Liebig acceded to the proposition at once, and sugfjested some 

 problem on the cheuiical nature of nitrogen ; this Wohler found 

 Himself unable to undertake, as it involved the u^e of rblorine, 

 to the actiDn of which he was at all times extremely susceptible. 

 On the other hand, he proposed to I.iebig that they should con- 

 tinue in common a research on mellitic acid, which he himself 

 had begun. Their joiit investigation on this body made its 

 appearance within the following year. 



It would be quite impossible within the limits of an hour to 

 attempt to give you anything approaching to a complete analysis 

 of Wohler's work. In all, he was the author of 275 memoirs 

 and papers, and of these fifteen were published in concert with 

 Liebig. I must therefore confine my selection from this vast 

 amount of material to those papers which are of paramount 

 importance from the influence which they have exerted on 

 chemical theory or on the development of the chemical arts. 



Very shortly after the publication of the work on mellitic 

 acid Wohler proposed to liebig a joint investigation on cyanuric 

 acid, in the course of which he observed the extraordinary 

 transformation of that acid into cyanic acid, and the reconver- 

 sion of the cyanic acid into cyanuric acid — one of the most 

 remarkable instances of molecular rearrangement known to the 

 chemist. The work progressed little for some months, owing 

 to the demands made by Berzelius's Jahre:.bcricht on Wohler's 

 time. " Wirfdie Schreiberei zum Teufel," wrote Liebig, "und 

 gehe in das Laboratorium, wohin Du gehorst." It was that 

 functionary, doubtless, who in due time carried off the wrilinc 

 to his master, the printer. Wohler went back to his laboratory, 

 and in a few weeks the two investigators had obtained the clue 

 to I he puzzle. Liebig wrote to Wohler: "Now that I have 

 received your experiments the whole thing is cleared up, and 

 with what satisfaction for u^ ! The matter is now decided : the 

 cyanic aid of Serullas is identical w ith that from urea. . . . Ich 

 bin ganz narrisch vor Freude, dass unser Kindlein nun fehlerlos 

 in die Welt gesetzt wird, ohne Buckel oder Klumpfuss." 



[It had been suggested to attack the fulminic acid again.] 

 " The fulminic acid we will allow to remain undisturbed. Like 

 you, I have vowed to have nothing more to do with this stuflf. 

 Some time back I wanted, in connection with our work, to 

 decompose some fulminating silver by means of ammonium sul- 

 phide ; at the moment the first drop fell into the dish the mass 

 exploded under my nose. I was thrown backwards, and was 

 deaf for a fortnight, and became almost blind." 



The work on cyanic acid appeared in Poggendorff's Annalen 

 during the last month of 1830, and Wohler was able to send the 

 "Kind ein" " im neuen Kleide," .is he says, with a New Year's 

 greeting to his friend. Liebig had suggested fresh work, but 

 at the moment Wohler was in no humour to attack anything 

 organic. The Swedish chemist, Sef>trom, had just announced 

 the existence of a new element in the sing of certain iron ores, and 

 this very substance had slipped through Wohler's fingers unper- 

 ceived. " I was an ass," he wrote to his friend, '-not to have 

 detected it two years ago in the lead ore from Zimapan in 

 Mexico. I was busy with its analysis, and had foimd something 

 strange in it, when I was laid up for some months in consequence 

 of breathing hydrofluoric acid, and so the matter was allowed 

 to rest. Meanwhile Berzelius sends me word of its discovery by 

 Sefstrom in Swedish bar iron and in slag. It is very like chro- 

 mium, and just as remarkable. Moreover, it is the same metal 

 that Del Rio found in the Mexican lead ore, and called erythro- 

 nium : Descotils, however, had declared this ore to be lead 

 chromate." 



Wohler, no doubt, found a ready sympathiser in Liebig, to 

 whom, not many years before, a similar experience had hap- 

 pened. We all know the story of the young chemist whose 

 unscientific use of the imagination cost hiin the discovery of the 

 element liromine. Wohler had sent some of the substance to 

 Stockholm, and Berzelius wrote as follows : — 



"Jacob Berzelius to Frederick Wohler 



" Stoci/10/m, yaniiary 22, 1831 

 "As to the small quantity of the body marked ? I will relate 

 the following .story : — ' In the far north there lived in the olden 

 time the goddess Vanadis, beautiful and gracious. One day 

 there came a knock at her door. The goddess was in no hurry, 

 and thought "They can knock again"; but there came no 

 further knock, for he who knocked had passed on. The goddess, 

 wondering who it could be that cared ^o little to be let in, ran 

 to the window and recognised the departing one. " Ah ! " .said 

 she to herself, " it is that lazy fellow, Wohler ! He richly 



deserves his name, since he cares so little to come in." Some 

 days after, some one else knocked, repeatedly and loud. The 

 goddess opened the door herself ; it was Sefstrom who entered, 

 and, as a consequence of their meeting, vanadium came to light.' 

 Your specimen with the ? is, in fact, vanadium oxide. 



" But he that his found the mode of artificially forming an 

 organic body can well renounce the discovery of a new metal ; 

 indefd, one might have discovered ten unknown elements with- 

 out as much skill as attaches to the masterly work which you 

 and Liebig have carried out together and just communicated to 

 the scientific world." 



In 1S31 Wohler was callel from Berlin to Cassel, and for 

 some little time he w.as wholly eng.iged in the planning and erec- 

 tion of his new laboratory at the Gewerlie-Schule in that town. 

 In the spring of the following year he was again ready for a new 

 research; and this time it was to be the finest piece of work 

 that the two investigators jointly engaged in. It was, in fact, to 

 be the classical research on bitter almond oil. On May 16, 

 1S32, Wohler wrote to Liebig: — "Ich sehne mxh nach einer 

 ernsten Arbeit, sollten wir nicht die Confusion mit dem Bitter- 

 mandelcil in's Reine bringen ? Aber woher Material ? " It 

 must have been a forsclicrbUrk amounting to inspiration which led 

 Wohler to take up this suliject ; but neither he nor Liebig could 

 have been wholly conscious of the consequences which were to 

 follow froii their work. To-day oil of bitter almonds is made 

 artificially in Germany by the hundredweight: at that time the 

 investigators could only obtain it in small quantities from Pari<. 

 They had indeed to thank Pelouze fjr the material with which 

 they worked. Wohler made this his greatest research under tht- 

 cloud of a great sorrow : after barely two years of married life 

 he lost his wife. Liebig, in the tenderest manner, brought him 

 over to Giessen, and sought to win him from his grief and the 

 sense of his loneliness by his company and the wholesome dis- 

 traction of their joint work made side by side. 



On August 30, 1832, Wohler wrote to Liebig from Cassel : — 



"I am here back again in my darkened solitude. I do not 

 know how I shall thank you for the affection with which you 

 received me and kept me by you for so long. How happy was 

 I that we could work together face to face. 



" I send you with this the memoir on bitter almond oil. The 

 writing has taken me longer than I anticipated. I want you to 

 read through the w hole with the greatest care, and to notice par- 

 ticularly the numbers and formula'. What does not please you, 

 al'er at once. I have often felt that there was something not 

 quite right, without l^eing able to find whit was right." 



I shall not attempt to dwell upon the outco'ue of this great 

 work. The iuA'cstigation on the radicle of benzoic acid will ever 

 remain one of the greatest achievements in the histoiy of organic 

 chemistry : the work was indeed epoch-making in the far- 

 reaching nature of its consequences. It was full of facts and 

 rich in the promise of new- material ; a veritable mine from 

 which subsequent workers like Cannizzaro, Fehling, Piria, Stas, 

 and Mlasiwetz have dug rich treasure. The immediate effect of 

 the paper was to establish the doctrine of organic radicles by 

 demonstrating the existence of groups of bodies wdiich had their 

 analogues and prototypes in inorganic chemistry. The concluding 

 words of the memoir strike, in fact, the keynote of the whole 

 investigation. "In once more reviewing and connecting to- 

 gether the relations described in this memoir," so WTote Liebig 

 and Wohler, " we find that they may be grouped round a com- 

 mon nucleus which preserves intact its nature and composition 

 in its associations with other bodies. This stability h.is induced 

 us to regard this nucleus as a kind of compound element, and 

 to propose for it the special name of * l.ienzoyl.' " 



A significant feilurc in the memoir was that each of the sub- 

 stances described and correlated was the type of a distinct group 

 of bodies, some of which were known, but of which the analo- 

 gies and relations vv<.re unthought of ; others of these bodies were 

 yet to be discovered, a matter of little difficulty when the modes 

 of their origin had been indicated. The effect of this memoir 

 on the chemical world vas instantaneous. Berzelius was de- 

 lighted. "The facts put forward by you," he wrote to Wohler 

 and Liebig, "give rise to such considerations that they may well 

 be regarded as the dawn of a new day in vegetal chemistry. On 

 this account I would propose that this first-discovered radicle 

 com]>osed of more than two elements should be named proiit 

 (from irpiA, the beginning of day) or orthrin (opSpos, daybreak), 

 terms from which names like proic acid, orlliric acid, proic 

 chloride, orihric chloride, &c., could be readily derived." 



