Book II. 
Division II. 
SALTS OF 
During this solution no hydrogen gas is emitted ex 
cept a few bubbles at first. The iron is oxidated at the 
expence of the acid, part of which is decomposed ; its 
oxygen combines with the iron and converts it into 
black oxide, while its sulphur combines with the sul 
phite of iron as it forms. The salt, therefore, which is 
obtained by this process, is not pure sulphite of iron, 
but that salt combined with sulphur. These pheno 
mena were first described by Berthollet *. When sul 
phuric acid or muriatic acid is poured into this solu 
tion the sulphurous acid is disengaged with efferve 
scence ; and if these acids be added in sufficient quan 
tity a portion of sulphur is precipitated. 
When the solution is exposed to the air, crystals of 
sulphite of iron are formed, and at the same time a red 
powder is deposited, probably consisting of oxy-sulpbite 
of iron with excess of base, and combined with sulphur. 
The crystals dissolved in water and exposed to the air 
are gradually converted into sulphat of iron. †. 
Thus there are two varieties of sulphited iron, simple 
sulphite and sulphurated sulphite. The first of these is 
insoluble in alcohol; but that liquid dissolves the se 
cond : the first, when exposed to the air, is converted 
into sulphat, but the second remains unaltered f. 
Sp. 3. Nitrated iron. 
NITRIC ACID acts with great energy upon iron, a 
violent effervescence takes place, nitrous gas is emitted 
in abundance, the iron is generally oxidated to a maxi 
mum, and a red powder precipitates, consisting pro 
bably of oxy-nitrat with excess of base. These pheno 
mena have been long known; but it was not till after 
* Ann. de Chim. ii. 58. 
Fourcroy, vi. 200. 
t Ibid.