LECTURE XL] HISTORY OF CHEMISTRY. 205 



alcohol and of ether. In conformity with Liebig's ethyl theory, 

 alcohol was pretty generally written C 4 H 12 O. 2 , and ether C 4 H 10 O 

 [C 12, O=i6]. Now, with the halving of the atomic weights, 

 the formulae had, in many cases, been halved : alcohol became 

 C 4 H 6 O. 2 , and ether C 4 H 5 O [C = 6, O = 8], whereas Gerhardt 

 assigned to these substances the formulae C 2 H 6 O and C 4 H 10 O 

 [C=i2, O=i6], Further, Laurent had already drawn atten- 

 tion to the fact, in i846, 30 that the formulae of alcohol and 

 ether, as well as those of potassium oxide and hydroxide, are 

 derivable from that of water. 31 He wrote : 



HHO EtHO EtEtO KHO KKO 



Water. Alcohol. Ether. Potassium Potassium 



Hydroxide. Oxide. 



Williamson perceived that the last view alone was in agree- 

 ment with his experiment. He formulated as follows the 

 equation which represented the reaction he had discovered : 



H 5 I = ?0 + KI [C = 1 2]. 



In order to meet the opposing view, in accordance with 

 which the equation ought to be written : 



C 4 H 5 O.KO + C 4 H 5 I - 2(C 4 H 6 0) 4- KI [C = 6] 



since the assumption was that potassium alcoholate is a com- 

 pound of potassium oxide with ether, and that the latter 

 separated during the decomposition, whilst a second " atom " 

 of the same substance was simultaneously produced from the 

 ethyl iodide, Williamson carried out the reaction with methyl 

 iodide. He expected to obtain methyl ethyl ether, whereas, in 

 accordance with the view just referred to, a mixture of methyl 

 ether and ethyl ether ought to be produced. The experiment 

 was, therefore, decisive and justified Williamson's hypothesis. 

 Both by the action of methyl iodide upon potassium ethylate 



30 Ann. Chim. [3] 18, 266. 31 Griffin claims priority of the view n 

 accordance with which the alkalies do not contain any water. See Griffin, 

 Radical Theory, 9. 



