with the Nitric and Nitrous Acids. 347 
from the subnitrite. This result naturally leads to this question: 
Is there a term at which the acid nitrate of lead boiled over this 
metal is converted into simple nitrite, sv that by stopping the 
operation at -this term we may obtain pure nitrite? I do not 
think that there are as yet a sufficient number of facts to resolve 
this question definitively: but all my experiments have yielded 
pure nitrite ; and I have observed besides, that when there was 
an evident production of subuitrite, nitrate was still found in the 
liquor. Another fact is, that nitrites, prepared in different ope- 
rations decomposed by the carbonic acid, have given the same 
quantity of carbonate ; which seems to indicate a constant com- 
position. 
Recapitulation. 
1. The oxide of lead boiled with the acid nitrate forms a salt, 
the base of which is double that of the acid nitrate. 
2. When we boil lead with acid nitrate, the metal is oxidated 
at the expense of the nitric acid, and passes to the state of li- 
tharge: the latter is united to nitrous acid. In this operation, 
therefore, there is a nitrate formed with a base of an oxide more 
at the minimum than litharge. 
3. The combination of oxide of lead with the nitric acid is 
not the only sait-of its kind which is converted into nitrite by 
lead ; the nitrate of potash undergoes asimilar decomposition. 
4. The nitrous acid gives with oxide of lead two combina- 
tions: the one, which is a subnitrite, is formed when we boil 
the acid nitrate of lead over this metal until there is no longer 
any action ; the other, which is the nitrite, is obtained by passing 
a current of carbonic acid into the solution of the subnitrite. 
5. The colour of the subnitrite more easily disappears than 
that of the nitrite, for the former does not colour the water like 
the latter. The proof that non-colouring of the water by the 
subnitrite is not owing to the salt being less soluble than the 
nitrite, is, that by precipitating from its polation a part of its 
oxide, the liquor becomes yellow. 
6. The solution of the two nitrites precipitates the nitrate of 
copper ; the precipitate is formed of two metallic hydrates, which 
probably retain a little nitric acid. 
7. The nitric acid and acetic acid, when boiling, emit nitrous 
vapour when we project into them the nitrites reduced into powder. 
8. The conversion of the nitrite into subnitrite by the oxide 
of lead, is very proper to prove that, in the preparation of the 
nitrite by M. Proust’s process, there is not formed any oxide more 
at the minimum than litharge ; for, if this were the case, instead 
of an oxide inferior to litharge, it must be acknowledged that 
there were two; since | have demonstrated that, by prolonging 
the ebullition of the acid nitrate of! lead over the metal, we ob- 
tain 
