ON THE PURIFICATION OF SULPHURIC ACID. 311 
ART. LII. — ON THE PURIFICATION OF SULPHURIC ACID. 
By M. Jaquelin. 
Sulphuric acid of commerce contains a certain quantity of 
nitrous acid, the presence of which is rendered manifest on 
the addition of proto-sulphate of iron, by the assumption of 
a violet tint, while with the pure acid no color is produced. 
It was long since proposed to boil the impure sulphuric 
acid with flowers of sulphur, which becoming acidified at the 
expense of the oxygen of the nitrous acid, destroys this latter, 
and thus purifies the acid. More recently M. Pelouze has 
proposed the addition of a certain quantity of sulphate of am- 
monia, and distilling; the ammonia and nitrous acid, by reac- 
tion, are changed into water and protoxide of nitrogen. M. 
Jaquelin proposed to treat the sulphuric acid at first with 
flowers of sulphur, then the product by chlorine, to convert 
into sulphuric acid any sulphurous acid which it may contain. 
The sulphuric acid is then to be boiled to drive off the excess 
of chlorine and the hydrochloric acid formed. 
According to M. Jaquelin, narcotine, which is recommended 
as a reagent for the detection of nitric acid in sulphuric acid, 
on account of the fine red color produced, is not to be relied 
on, since even to pure sulphuric acid it communicates a yel- 
low color, which might produce an error. 
Journ. de Pharm. et de Chim. 
