ON THE MANUFACTURE OF SULPHURIC ACID. Ill 
pounds of concentrated acid, at the cost (in Paris) of H cents 
per pound. The above proportion is about the theoretical quan- 
tity to be given by 100 pounds of sulphur; the sulphur used 
containing five per cent, of impurity. The quantity of oxygen 
yielded by the nitric acid used, is about one-fifth of that re- 
quired to oxidate the sulphurous acid; the remainder must of 
course be supplied by the atmospheric air, which obtains access 
into the chambers. 
The theory of the formation of sulphuric acid by this method 
is somewhat obscure, and we can only attain to a perfect know- 
ledge of it, by knowing what interchange of elements takes 
place within the chambers. But from the known fact that sul- 
phuric acid cannot be made by these means, unless the water 
in the chamber is previously acidified by sulphuric acid, it is 
probable that this acid acts as a catalytic agent in producing 
the decomposition of the nitric acid, and that thence the same 
phenomena result as in the process for the manufacture of sul- 
phuric acid by means of sulphur and nitrate of potassa. 
R. B. 
