206 HISTORY OF CHEMISTRY. [LECTURE XI. 



and by that of ethyl iodide upon potassium methylate the so- 

 called mixed methyl ethyl ether was produced : 



5 + 1C H 3 = >25 + IK 



K ^ -ti 



These experiments proved to Williamson that ether is 

 produced from alcohol by the replacement of an atom of 

 hydrogen by ethyl, and, therefore, that it contains more carbon 

 in its molecule than alcohol does. The formation of the mixed 

 ethers furnished him with a reason for excluding every other 

 view. 



It now became a question to explain the formation of ether 

 under known circumstances, especially by the treatment of 

 alcohol with sulphuric acid ; and the solution of this problem 

 was also furnished by Williamson, after chemists had been 

 engaged upon it for decades. At first the process of etherifica- 

 tion had been explained by the dehydrating action of sulphuric 

 acid. 32 This view agreed very well with Dumas' etherin theory. 

 Hennell, although an adherent of the etherin theory, considered 

 this view irreconcilable-with the formation of sulphovinic acid 

 observed by him ; 33 and it was also in contradiction with the 

 fact that water distils over at the same time as the ether. It 

 was Liebig, especially, who established by means of numerous 

 experiments a new theory of etherification. 34 He ascertained 

 that the formation of ethyl sulphuric acid precedes that of 

 ether, and, according to him, the sulphuric acid does not with- 

 draw water from the alcohol, but ether, which latter unites with 

 the sulphuric acid. Indeed ethyl sulphuric acid was at that 

 time looked upon as a compound of these two substances, that 

 is, as an acid salt of ethyl oxide. 



Thus ethyl sulphuric acid = C 4 H 10 O + 2SO 3 + H,O 

 [C=i2, 0=16,8 = 32]. 



32 Compare especially Fourcroy and Vauquelin, Scherer's Journal 6, 

 436 ; also Gay-Lussac, Ann. Chim. 95/31 1, and [2]2, 98. 33 Phil. Trans. 

 1828, 369. a4 Annalen. 9, 31 ; 13, 27 ; 23, 31. 



