290 ON THE MANUFACTURE OP SULPHURIC ACID. 
But from my investigations concerning the nature of the 
crystals which form in the lead-chambers, it results that the 
sulphurous acid reduces the hyponitric acid to nitrous acid. 
This result, which led me to consider the theory of M. de 
la Provostaye as incorrect, induces me also to show that 
that of M. Peligot is erroneous. 
M. Baudrimont adopts, with the followers of the theory 
of M. Gaultier de Claubry, that the crystals, or at least an 
analogous compound, is indispensable to the formation of 
sulphuric acid ; but this theory does not answer to the facts; 
for, as M. Peligot has proved, sulphurous acid is capable of 
deoxidizing nitric acid in the presence of a considerable 
quantity of water. This proves that the compound (SO 3 
N0 3 + SO 3 HO) is not absolutely requisite, as was hitherto 
supposed, for the formation of sulphuric acid. 
The sulphurous acid acts under these circumstances, de- 
oxidizing precisely like hydrochloric acid, with which it 
possesses the same property in respect to nitric acid, and 
in almost the same degree. As long as the latter is not too 
diluted, the first two convert it into nitrous acid, which is 
decomposed into nitric oxide and nitric acid, if there is suffi- 
cient water present ; but in the manufacture of sulphuric 
acid the quantity of water is seldom large enough for this 
change to take place, for it is not to 8 the interest of the manu- 
facturer to exclude from action one of the generators of his 
product, nor to convey more water into his lead-chamber 
than requisite for the formation of the acid ; nor is it more 
requisite that he should introduce dilute acid into his large 
chamber at the commencement of the operation ; it suffices 
if there be a sufficient quantity of aqueous vapour present 
to prevent the formation both of crystals as well as of nitric 
oxide. The reaction goes on regularly, and the product 
only contains traces of nitric acid ; but then follows the re- 
action between sulphurous acid, nitric and hyponitric acid ; 
for the hyponitric acid, which is produced by contact with 
sulphurous acid, instead of being oxidized and converted 
