208 HISTORY OF CHEMISTRY. [LECTURE XI. 



whilst the formation of the ethyl sulphuric acid is represented 

 by this one : 



5 



o = o + 'so* 



If the latter equation is read from right to left, it explains 

 Graham's experiment of the decomposition of ethyl sulphuric 

 acid into alcohol and sulphuric acid. As soon as the doubled 

 formula for ether was admitted, it was comprehensible why 

 ether is not produced by heating ethyl sulphuric acid. 



Williamson, however, not contented with having shown the 

 accuracy of his opinions by their being in harmony with the 

 known facts, devises new experiments by which he can test 

 them. 38 The method he adopts is the same as previously. 

 He chooses the two substances which act upon one another from 

 groups containing different numbers of carbon atoms. He now 

 causes ethyl sulphuric acid and amyl alcohol to interact, and 

 this reaction gives rise to the expected ethyl amyl ether : 



c |f 5 so 4 + C5 ^ n o = ^so 4 + CH"O. 



He studies, besides, the action of sulphuric acid upon mix- 

 tures of ethyl and amyl alcohols, and is able to show the 

 formation, in this case, of three ethers ethyl ether, amyl ether, 

 and ethyl amyl ether. He finds " in these reactions the best 

 evidence of the nature of the action of sulphuric acid in form- 

 ing common ether, or in accelerating the formation of the so- 

 called compound ethers ; for acetic ether is formed from acetic 

 acid, just as ethylic ether from alcohol, by the replacement of 

 hydrogen by ethyle. And if the circumstance of containing 

 hydrogen, which is replaceable by other metals or radicals, be 

 the definition of an acid, we must consider alcohol as acting the 

 part of an acid in these reactions." 



A further consequence of Williamson's experiments was the 

 fixing of the molecular weight of acetic acid. According to 

 Williamson, this acid is formed from alcohol by the replace- 

 ment of two hydrogen atoms of the ethyl group by an atom of 



38 Journ. Chem. Soc. 4, 229 ; Annalen. 8x, 73 * 



