LECTURE VIII.] HISTORY OF CHEMISTRY. 135 



the accuracy of his ideas. 21 He regards these compounds as 

 analogous to alcohol; they are composed of ethyl sulphide 

 C 4 H ]0 S, and sulphuretted hydrogen H 2 S, and their extremely 

 interesting metallic compounds show that in them there really 

 are two hydrogen atoms which behave differently from the 

 others. Two years later, in 1836, he collects together all the 

 grounds for and against each view ; 22 and from the most 

 various facts (but especially from the phenomena of substitution, 

 already discovered by Dumas), he considers himself justified 

 in drawing the conclusion that ether is not a hydrate but an 

 oxide. 



The matter was not yet settled, however. In his examina- 

 tion of wood spirit (carried out in conjunction with Peligot), 

 Dumas had found new support for his views. 23 He succeeded 

 in settling the composition of this substance, a matter that 

 different chemists had attempted to settle, but without success. 

 He showed that in its whole behaviour it had the closest 

 resemblance to alcohol, forming, as the latter does, ethereal 

 compounds with acids ; and he assumes in it the radical C 2 H,, 

 methylene, with which etherin is polymeric. The advantages 

 of this way of regarding the matter, which does not lead to the 

 assumption of hypothetical radicals, are again pointed out. 24 



The discussion between Berzelius, Dumas, and Liebig, of 

 which I have given some examples, was of much service to our 

 science. The facts were illuminated from the most different 

 points of view, and this was far more favourable for progress 

 than if a single theoretical opinion had come too prominently 

 to the front. The chemists just mentioned were the chief 

 exponents of chemistry at that time, and round them the 

 other investigators gathered. Of these, only a few represented 

 independent opinions, and chemists were divided, accordingly, 

 into three camps. It is true that in 1837 a sort of armistice 

 was concluded. At a personal interview, Liebig converted 



21 Annalen. II, 10. 22 Ibid. 19, 270, Note. ' 23 Ann. Chim. [2] 58, 

 5 ; Annalen. 13, 78 ; 15, I. 24 Dumas and Peligot believe that they can 

 isolate methylene. 



