On definite Proportions. 459 
a dark brown colour, and frothed very much while it wag 
decomposed. A part of the acid which escaped was in the 
form of a gas ;. another part was collected as a liquid in the 
receiver: the salt contains therefore water of crystallization. 
A melted protoxide remained in the retort, weighing seven 
“grains” [grammes]. Without doubt this salt contains 
at least twice as much acid in proportion to the base, as the 
subnitrite, and consequently the nitrous acid must saturate 
in the neutral salt a quantity of the protoxide containing + 
as much oxygen as the acid; that is, 100 parts of the acid 
must saturate 994°1 of the protoxide. This is the less ques- 
tionable, since the 100 parts of nitrous acid, considered as 
composed of nitrogen and oxygen, contain ‘three times as 
much oxygen as the 29471 parts of protoxide; so that both 
views of the subject are consistent with this result, If now 
the water of crystallization contains an equal quantity of 
oxygen with the base, the composition of the neutral mitrite 
of the protoxide of Jead must be this: 
Protoxide of lead ..  «. 70°375 
Nitrous acid .. .. »2 23°9295 
Water tive) eth nae bs oe 9) 52700 
In the experiment, the salt left only 70 per cent. of the 
protoxide: the slight difference of nearly 74,5 probably de- 
pends on the gradual oxygenization of the nitrous acid 
during the evaporation, whence the salt must contain a 
smaller quantity of the base. 
3. Subsubnitrite of ihe Protoxide of Lead. 
The subsubnitrite of the protoxide of Jead is a salt but 
little soluble in cold water. While the solution is cooling, 
it shoots into small crystalline scales of a dark brick colour. 
The solution is decomposed by exposure to the air, or by 
mixture with unboiled water, and copiously deposits a white 
powder. The dry salt may be kept in the air without alter- 
ation. {[t does not melt by heat, and at a temperature not 
very high it may be freed from all its w ater, without the 
extrication of any part of the acid; so that it seems to con- 
tain no water of crystallization. When I ignited 10 gr. of 
the subsubsalt well dried, in a small glass retort, I obtained 
only gaseous nitrous acid, and 8: 9825 gr. of protoxide were 
left behind: consequently this salt is thas composed ; 
Protoxide of lead .. ... 8$9°825 
Wittous acid) 4 ai feiss LOtig-5 
We find on computation, that this quantity of nitrous 
acid, considered as composed of nitrogen and oxygen, con- 
tains the same quantity of oxygen “with the protoxide, 
agreeing 
