8 ':";. BioldgJeaji Chemistry. 



onwards the>t)}.dipr :di vision, of chemistry into the three 

 branches ceased ; substances were thereafter divided into 

 two groups, according to whether they were of mineral or 

 " inorganic " origin or of " organic " origin. This sub- 

 division of substances was reflected in the science of 

 chemistry itself, which came to be divided into two main 

 branches, namely, mineralogical or inorganic chemistry 

 and organic chemistry ; or, as the latter was defined by 

 Gerhardt in 1844, the chemistry of carbon compounds. 

 This dual subdivision has been further justified by the 

 fact that many organic substances can be derived from 

 both animals and plants, and that where a substance 

 exists only in one kingdom, it generally has a chemical 

 analogue existing in the other. 



It is not possible within the limits of this book to 

 follow in any detail the history of the study of organic 

 chemistry during the early years of its development. Its 

 main function came to be recognized as the determination 

 of the " structure " of the various carbon compounds that 

 is, the re]ative arrangement in space to one another of 

 the various atoms of which the molecule is composed. 

 Students of organic chemistry concentrated their attention 

 on the various compounds themselves without any refer- 

 ence to their mode of formation in nature ; in fact, it was 

 at first generally held that products derived from animals 

 or vegetables owed their formation to some peculiar 

 " vital " process and could not be artificially produced by 

 any laboratory process, and in this respect they were 

 supposed to differ from the inorganic or mineral com- 

 pounds of which many " syntheses " had been accomplished. 

 The lines of demarcation between vital and non-vital and 

 organic and inorganic compounds were broken down in 

 1828, when Wohler published his synthesis of urea, a 

 substance which had been obtained hitherto only from the 



