354 Mr. A.Williamson's Theory of JEtherification. 



acid coming in contact with an atom of alcohol, it reacts ex- 

 actly in the same manner as the iodide did, forming of course 

 sulphuric acid and aether : 



nz U5 ^G xj ^G 



H Q C 2 H* 



C 2 H 5 u C 2 H 5 u 



The sulphuric acid thus reproduced comes again in contact 

 with alcohol, forming sulphovinic acid, which reacts as before; 

 and so the process goes on continuously, as found in practice. 



We thus see that the formation of aether from alcohol is 

 neither a process of simple separation, nor one of mere syn- 

 thesis ; but that it consists in the substitution of one molecule 

 for another, and is effected by double decomposition between 

 two compounds. I therefore admit the contact theory, inas- 

 much as I acknowledge the circumstance of contact as a ne- 

 cessary condition of the reaction of the molecules upon one 

 another. By reducing the formulae of the alcohols to one atom 

 of oxygen, I also retain the equality of volumes which the con- 

 tact theory insists upon between the vapours of these bodies 

 and their aethers, so that aether truly contains the elements of 

 oleflantgas in addition to those of alcohol in one atom. But, 

 on the other hand, I attach equal importance to all the essen- 

 tial facts of the chemical theory, and rest my explanation of 

 the process as much upon them as upon those of the contact 

 theory ; for, one-sixth of the hydrogen in alcohol truly ex- 

 hibits different reactions from the remaining five, and must 

 therefore be contained in that compound in a different manner 

 from them ; and the alternate formation and decomposition 

 of sulphovinic acid is to me, as to the partisans of the chemical 

 theory, the key to explaining the process of aetherification. 



Innovations in science frequently gain ground only by dis- 

 placing the conceptions which preceded them, and which served 

 more or less directly as their foundation ; but, if the view which 

 I have here presented be considered a step in our understand- 

 ing of the subject, I must beg leave to disclaim for it the title 

 of innovation ; for my conclusion consists in establishing the 

 connexion and showing the compatibility of views which have 

 hitherto been considered contrary ; and the best possible jus- 

 tification of the eminent philosophers who advocated either 

 one of the two contending theories, is thus afforded by my 

 reconciling their arguments with those of their equally illus- 

 trious opponents. 



Before quitting the subject of aetherification, I would wish 

 to add a few words on an application; which naturally enough 



