Mr. A. B. Northcote on Parathionic Acid. 223 



into account every known difference in the genesis of a body in 

 the hope of obtaining thence some elucidation of its structure. 



I cannot but think, then, that in the original reaction of 

 Hennel and Berthelot is to be found the cause of the difference 

 in the sulphovinic acids, and that in all cases in which the stable 

 varieties are produced, whether directly or as the result of de- 

 composition, the molecule C" H 2w may be traced in their struc- 

 ture, whilst in the unstable ones some other arrangement may be 

 found to exist. The reaction of ethylene on sulphuric acid 

 would therefore appear thus : 



HI C 2 H 4 .H"1 



C 2 H 4 -|-S0 2 ^0 2 = SO 2 ^O 2 . 



hJ hJ 



Berthelot* has expressed his belief that the althionic acid of 

 Regnault, to which he assigned the same formula as that of 

 sulphethylic acid, is identical with the stable sulphethylic acid, 

 the parathionic acid of Gerhardt; and by what means was it 

 obtained ? By heating a mixture of alcohol and oil of vitriol to 

 the point at which it began to evolve defiant gas, and then 

 arresting the action by saturating with a carbonate. Now we 

 know that alcohol and oil of vitriol at a moderate temperature 

 produce ordinary sulphethylic acid, which at an augmented tem- 

 perature decomposes, and, we may suppose, with an intermediate 

 staffe 



C 2 H 5 1 C 2 H 4 .H1 HI 



SO 2 ^0 2 = SO 2 ^0 2 =C 2 H 4 + S0 2 lo 2 . 



H J H J H J 



But the final action is in this case arrested by saturation — pro- 

 bably, however, not before the molecular disposition which gives 

 the stable sulphethylate is brought about ; and the carbonate 

 then acts upon the modified acid : 



2 l+Ba 2 C0 3 = 2 



+ H 2 C0 3 . 



There is yet that pair of reactions productive of the stable 

 sulphovinates which may be represented by the action of water 

 on the sulphate of methyle and on the sulphomethylate of barium ; 

 and of these the first alone needs consideration, since the expe- 

 riments of Churchf have made it almost certain that the first 

 result of the action of water on the latter salt is the production 

 of sulphate of methyle. The action of water on sulphate of 

 methyle is to produce methylic alcohol and /3-sulphomethylic 



* Jahresbericht (1855), p. 603. 

 t Phil. Mag. January 1856. 



