348 — On the Combinations of. the yellow Omide of Lead. 
tain a salt quite different from M. Proust’s, insomuch as it 
contains more lead. Now this opinion being admitted, it would 
be no longer possible to explain how M. Proust’s yellow salt 
could be converted by litharge into a salt the base of which was 
less oxidated than his. 
9. The combinations of the oxide of lead with the nitrous acid 
_ confirm the laws established by Richter, Gay-Lussac, Wollaston 
and Berzelius: thus the quantity of base of the subnitrite is 
double that of the nitrite. The composition of the nitrite cor- 
responds with that of the nitrate of lead; and a remarkable re- 
sult, if it be not accidental, is, that the carbonic acid, by taking 
from the nitrites a portion of base, leaves in the liquor a quan- 
tity of oxide, which is to that of the nitrous acid in a proportion 
which seems to correspond with that of the elements of the acid 
nitrate. But the cohesion of the nitrite and the expansive force 
of the acid are sufficient to overcome the affinity of the nitrite for 
an excess of its acid ; so that, by concentrating by heat the solu- 
tion of the nitrites when passed to the earbonic acid, we obtain 
nitrite by cooling *. It would be curious to ascertain if, in the 
decompositions analogous to that of the nitrite, something similar 
‘does not take place in the proportion of the principle which has © 
become predominant. This would be the means of ascertaining 
if the result which I have observed is not accidental. It would 
be also interesting to ascertain if the alkalis, in acting on the acid 
nitrate of lead, do not produce a subnitrate corresponding to the 
subnitrate. 
10. I have mentioned several facts in this memoir, which prove 
that we obtain nitrites intermediary between the two combina- 
tions which I have. described. May we regard these salts as so 
many different kinds of nitrite, or as combinations of the two 
nitrites? This is precisely what I cannot decide in a definitive 
manner: I shall therefore leave to my readers the liberty of 
forming any opinion they may think most natural. 
11. I have not been able to obtain pure nitrite by M. Proust’s 
process: for, if I do not deceive myself, the salts which I have 
prepared by this process were a combination of nitrite and ni- 
trate: this is what I have endeavoured by examining the action 
which they experience from carbonic acid and water.  Al- 
though I was not able to make pure nitrite by boiling the acid 
nitrate of lead over this metal, I have not affirmed that it is 
impossible to do so; because the want of success in operations 
of this kind is frequently owing to circumstances which it is not 
always easy to ascertain. 
* It is not improbable that by counteraeting the canses which tend to 
prevent the combination of the nitrite of lead with an excess of its acid, 
we may succeed in obtaiming this combination in the solid state. 
LXXIII. New 
