XVII 



Wohler finished up his stay in the north by a scientific journey 

 through Scandinavia in company with Berzelius and the two Brong- 

 niarts. The most interesting part of this excursion was a visit paid 

 to the copper and silver mines of Fahlun, rich in mineral and geological 

 treasures, and remarkable for the deep chasms which were formed 

 centuries ago by the falling in of immense vaults. During this 

 journey Wohler was fortunate enough to get acquainted with several 

 distinguished men of science, among them Sir Humphry Davy and 

 Hisinger, whose mineralogical geography he afterwards translated 

 into German. 



With much regret Wohler at last parted with his friend and teacher 

 Berzelius and returned to Frankfort. His idea had been to settle 

 down in Heidelberg as Privat Docent, but he was at once appointed 

 lecturer in the newly established Gewerbeschule (Mechanics' Institute) 

 at Berlin, and there he remained from 1825 to 1832, when family 

 affairs decided him to move to Cassel. 



It was in this same year 1825 that Wohler became acquainted with 

 Liebig, who was about his own age, and henceforth they were in 

 constant intercourse. Liebig had become Professor of Chemistry at 

 Giessen at the age of twenty-one, in the year 1824, and he followed 

 Wohler's work with all the greater interest because his own lay very 

 much in the same direction. 



These two investigators had each discovered a substance which 

 according to minute analysis were composed of precisely equal quantities 

 of the same elements. At that time it seemed like a paradox to say 

 that two such different bodies as cyanic acid discovered by Wohler, 

 and fulminic acid which Liebig had examined, could have the same 

 composition, for identity of composition in conjunction with difference 

 of property was at that time quite unintelligible. Another research 

 of far greater importance to the theory of organic compounds was an 

 investigation made in the year 1832 of oil of bitter almonds and of 

 benzoic acid. From these analytical experiments resulted a series of 

 new compounds which were connected together by the fact of their all 

 containing one particular group of atoms to which was given the name 

 of benzoyl radical. Thus by one stroke was the connexion between 

 all the members of this series of compounds made clear. The impres- 

 sion made by this research on contemporary chemists is plain from a 

 letter written by Berzelius to the two investigators, in which he 

 proposes for benzoyl the fanciful name "proin " (daybreak), or other- 

 wise ' 'dawn," because with the discovery of this radical a new day 

 seemed to dawn for chemical science. 



A new day had indeed dawned for chemistry, and after fifty years 

 the noon of this day shows us a vast number of substances with the 

 most beautiful properties, some with the most brilliant colours, others 

 of great value in medicine and surgery, all of which have been dis- 



vol. xxxv. G 



