A CENTURY OF CHEMISTRY. 97 



in 1898, after years of preparation, Professor Dewar 

 produced liquid hydrogen, — a clear, colourless liquid, 

 about one-sixth the density of liquid marsh gas, or 

 about one-fourteenth the density of liquid water at 

 0°. As Prof. Tilden remarks: " It was both inter- 

 esting and gratifying that the final victory which 

 crowned the long series of successful attacks upon 

 the apparently impregnable position of the perma- 

 nent gases should have been recorded in the labora- 

 tory of the Koyal Institution, where the first suc- 

 cesses in this field were won by Faraday." * 



DEVELOPMENT OF ORGANIC CHEMISTRY 



Organic and Inorganic Chemistry. — The distinc- 

 tion between the substances found in plants and 

 animals and those in the not-living world is an old- 

 standing one. Rooted in the belief that the sub- 

 stances composing or formed by living creatures were 

 under the domination of a specific vital force, the 

 distinction was for a time accented by the complex- 

 ity of most of the substances in question, by the fact 

 that they were often difficult to isolate and very 

 ready to change, and by the absence of a secure 

 method of analysing their composition. Later on, 

 the generalisations reached by the students of inor- 

 ganic substances did not seem to fit in well with Avhat 

 was known in regard to the organic, and the breach 

 was widened. It was thus to a large extent inde- 

 pendently that organic chemistry developed, until it 

 became strong enough to react upon the study of the 

 inorganic with a potent and progressive influence. 



" At the beginning of the century, when qual- 



* For a brief account of the subject the reader is referred 

 to Chapter IX. of Tilden's Bhort History of the Progress 

 of Scientific Chemistry, London, 1899. 



7 



