LECTURE XL] HISTORY OF CHEMISTRY. 207 



Ethyl sulphuric acid, according to the experiments of Liebig, 

 breaks up between 127 and 140 into ether and sulphuric acid. 

 The remarkable phenomenon that a substance is produced and 

 undergoes decomposition in the same operation, was explained 

 by Liebig on the assumption that the formation only occurred 

 at those places where the alcohol dropped in, and where, there- 

 fore, the temperature was lowered to the boiling point of this 

 liquid. The process of etherification therefore consisted, accord- 

 ing to Liebig, in the combination of the sulphuric acid with the 

 ether of the alcohol, and the decomposition into its constituents 

 of the compound so formed, at parts of the liquid where the 

 temperature was higher. Ether then distils over, and, along 

 with it, the water which was separated on the formation of the 

 ethyl sulphuric acid. 



In opposition to this theory Berzelius 35 advanced another 

 view, which was supported and developed by Mitscherlich in 

 particular. 36 According to this view, the sulphuric acid acts 

 by contact, taking no part in the reaction, and simply decom- 

 posing the alcohol into ether and water by catalytic action. 

 This was a mode of expressing the facts by means of specially 

 chosen words, but it can scarcely be called an explanation. 

 Liebig's hypothesis really embraced an explanation which was 

 pretty generally accepted. It was only called in question after 

 Graham had shown, in i85o, 3T that alcohol and ethyl sulphuric 

 acid are both necessary for the formation of ether ; and that 

 the latter of the two does not yield ether even when heated 

 alone to 143, but decomposes, in presence of water, into 

 alcohol and sulphuric acid. 



Williamson clearly understands how to apply these facts. 

 The formation of ether is explained by the following equation : 

 C 2 H 5c , n , Q>H 5 ^ _ H^x-v C 2 H 5 ~ 

 H oU 4 + H - H bU4 + C 2 H 5 U ' 



sufpSc Alcohol. Su S rk Ether, 

 acid. 



85 Berzelius, Jahresbericht 1836, 241. 36 Pogg. Ann. 53, 95 ; 55, 

 209. 37 Journ. Chem. Soc. 3, 24 ; Annalen. 75> IQ 8 ; compare Journ. 

 de pharm. [3] 18, 30. 



