PROBLEMS OF MODERN SCIENCE 



contained hydrogen and oxygen. Lavoisier was 

 also able to detect the presence of nitrogen and 

 phosphorus in many substances of animal origin, 

 and, being unable to find these elements in plant 

 materials, he considered that the two types of 

 product were different in character, and he there- 

 fore was inclined to retain the distinction made 

 previously on purely formal grounds. 



With the advance in methods of analysis it 

 was soon found that nitrogen and phosphorus 

 are present in many substances obtained from 

 plants, and, Lavoisier's distinction being no longer 

 justified, the chemistry of the two groups became 

 fused together under the name 'Organic Chemistry,' 

 or the chemistry of substances formed under the 

 influence of vital forces. It was recognised that 

 the substances obtained from plants or animals 

 always contained carbon. Moreover, quantitative 

 analysis showed that they were usually more com- 

 plex than the compounds obtained from mineral 

 sources, and were of a quite different chemical 

 nature, being more easily decomposed by heat and 

 by chemical agents. 



These distinctions between the two groups 

 were mainly of a chemical nature, but another 

 fundamental difference seemed to justify the 

 separation of mineral from organic chemistry. It 

 had been found that many compounds of mineral 

 origin could be reproduced by synthesis in, the 

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