80 ACTION OF SULPHUROUS ON HYPONITRIC ACID. 
N O,; and in the second, SO, O, SO, N O, + hydrated sul- 
phuric acid. 
It is therefore evident—1st, that the crystals are never formed 
without the presence of free sulphuric acid; 2nd, that when free 
they are invariably destroyed by water. If water appear indis- 
pensable to the formation of crystals, in the experiment com- 
monly exhibited at the lecture-table, it acts only in an indirect 
manner, by giving rise to sulphuric acid. In fact, the crystals 
may be obtained much more readily, and in larger quantity, if 
sulphuric acid be previously employed to moisten the flask used 
in this experiment. 
In the new manufacturing process the nitric acid yields one 
portion of itsoxygen to sulphurous acid, which becomes sulphuric 
acid. Proceeding from this as a starting-point, reduced as the 
nitric acid is, to the state of hyponitric, it acts as the hyponitric 
acid does, resulting from the union of nitric oxide with the oxygen 
of the air in the old process ; that is to say, it alternately yields 
oxygen to the sulphurous acid, and abstracts it from the air: but 
these changes require the intervention of sulphuric acid and of 
water. The water may possess two very distinct functions ; it can 
act directly by condensing and bringing the sulphurous and hy- 
ponitric acids into closer contact, and thus enable the first to ob- 
tain oxygen from the second. But this, which is a slow reaction, 
is not the most important function of water, as it acts much 
more efficaciously in another manner in concert with sulphuric 
acid. The latter determines a rapid formation of white crystals, 
and also of a thick and heavy vapour of a fawn colour, which 
contains a considerable quantity ; these are decomposed by the 
water; becoming immediately transformed into hydrated sul- 
phuric acid, and nitrous acid or nitric oxide. The reaction of 
the latter recommences, and may be continued indefinitely. 
Such is, if I am not deceived, the true account of the changes 
in the manufacturing process for sulphuric acid. 
To sum up briefly the results of this investigation ; they are,— 
1st, the formation of a new substance through the action of sul- 
phurous acid on hyponitric acid; 2nd, an explanation of the 
discordant results obtained by other chemists in examining the 
crystals of the leaden chamber ; and, 3rdly, amore complete and 
exact theory of the complicated phenomena which are present- 
ed in the manufacture of sulphuric acid. 
