SULPHUROUS ACID ON HYPONITRIC ACID. 79 
which occur in the leaden chamber, and afford a clear elucida- 
tion of the theory of the manufacturing process for sulphuric 
acid. 
First, of the new process, in which sulphurous acid, nitric acid 
and aqueous vapour are conducted into the leaden chambers. In 
order to ascertain what takes place in this process, a current of 
sulphurous acid was passed into a flask containing nitric acid ; 
the latter, again, was connected, by means of a bent tube, with 
a flask containing oil of vitriol, that with a vessel moistened with 
water, and the last with a dry flask. The nitric acid was en- 
tirely decomposed, the first flask containing in a short time 
nothing more than free sulphuric acid. Red vapours travelled 
from the first to the second vessel: sulphurous acid likewise 
entered it, for white crystals were produced even in the last 
vessel of the series. All the sulphuric acid contained in the se- 
cond vessel became a crystallized mass, of a faint greenish yellow 
colour. The reactions are, therefore, in the main, of the same 
nature as in the ordinary process. 
Secondly, of the common process. In a chamber, the bottom of 
which is covered with sulphuric acid, and into which steam is con- 
tinually injected, sulphurous acid, nitric oxide and air, or, in other 
terms, sulphurous acid and hyponitric acid in the nascent state, 
are introduced. It is generally admitted that these two bodies, 
which do not combine when dry, can unite under the influence 
of water, in the state of sulphurous and nitrous acids; and, in 
the second place, that the crystals formed are decomposed by 
the smallest quantity of water in excess. 
It was, at least, singular, that water could thus produce two 
absolutely contrary effects; but we can now affirm, that this 
idea is groundless, since, according to my experiments, water 
immediately causes the decomposition of the anhydrous com- 
pound, which would evidently never have occurred, had water 
possessed a tendency to preserve the union of its constituents. 
Let us examine matters a little closer. 
Tf sulphurous acid and oxygen gases be mixed and put in 
contact with water, sulphuric acid is gradually produced. But 
this acid is more expeditiously produced from sulphurous and 
hyponitric acids; but even in the last case the reaction is by no 
means rapid. These same bodies, on the contrary, act with 
great energy in the presence of anhydrous or hydrated sulphuric 
acid, forming, in the first instance, the compound S O, O, S O, 
