406 On the Nitrates and Nitrites of Lead. 
*e 
and the tubes which had been weighed full of air, made it full 
of nitrous acid gas: hence the subnitrite at the minimum can- 
not contain 6°4 of pure water, as M. Berzelius says. I have 
said that this result confirmed that of my analysis; for, accord- 
ing to the latter, there must have been more than 2°26 of water 
in 100 of subnitrite at the minimum: now we can easily con- 
ceive that the latter had been able to absorb nearly its weight 
of nitrous and nitric acid. I shall now detail another method of 
determining the water of crystallization of the subnitrite at the 
minimum, and it is entitled to the more confidence as I shall 
deduce it from experiments described in my memoir. 
When we pass into a solution at the maximum a stream of 
carbonic acid, we precipitate from it such a portion of oxide 
that the portion which is not precipitated is to the acid in the 
relation of 72:48 to. 27°52: this ratio seems constant; for I 
have shown that the quantity of water in which the subnitrite 
was dissolved had no sensible influence on the result. The de- 
composition is stopped by the presence of an excess of nitrous 
acid: now the subnitrite at the minimum being partly decom- 
posed by the carbonic acid, it is evident that the two decompo- 
sitions ought to expose a quantity of nitrous acid, which ought 
to be to the oxide not precipitated in the same ratio. This 
being the case, we may know the quantity of acid contained in 
the subnitrite at the minimum, if we have determined the pro- 
portion of the elements of the subnitrite at the maximum, and 
the quantity of the base of the subnitrite at the minimum. Now 
M. Berzelius and I are agreed as to these quantities: we admit 
80 as the base in the subnitrite at the minimum: several ex- 
periments which I made on the decomposition of the subnitrite 
at the minimum proved to me that the carbonic acid separated 
from five grammes of this salt 1°74 gr. oxide, of which there re- 
mained in the liquor 2:26 of base: now when we establish this 
proportion, 72°48: 27°52: : 2°26: 9, we shall have 0-858 of ni- 
trous acid contained in five gr. of subnitrite at the minimum, 
Now if we subtract from 5 gr. 4 gr. of base and 0°858 of acid, 
there will remain 0-142 for the water of crystallization, or for 
100 Aer Le be eSB Go. ty Od enh 
Oxide cen gee. .o000) 3 S253 23465 
Water..... eT A 
According to the first determination, I had admitted a little 
more than 2:26 of water. If we now calculate the proportion 
of base contained in the subnitrite at the maximum, supposing 
that it is double that of the subnitrite at the minimum, we shall 
have 90:2 instead of 90:1, which I found by experience. 
ma | LXXXVII. On 
