266 On the Combinations of the yellow Oxide of Lead 
11. The small quantity of oxygen which the lead seemed to 
absorb im order to be oxidated at the minimum, and the reflec- 
tion that this quantity did not follow any relation with the 
known oxidations of this metal, began to create doubts in my 
mind as to the existence of an oxide more at the minimum than 
litharge, and incline me to think that it was not improbable that 
the lead was oxidated at the expense of the nitric acid of the 
nitrate ; that conseque ently the salt obtained from this operation 
was only a nitrite with a base of litharge ; ; and that the nitrous 
acid extricated from this salt by the nitric acid (6) was merely 
separated from it, as when we pour nitric acid over an alkaline 
nitrite. What supported this opinion was: Ist, the uitrite of 
potash which I found in the mother water of the salt (9)5  2dly, 
the litharge and the nitrous acid which this salt constantly 
yielded, whether [ decomposed it by heat, treated it with acetic 
acid, or with carbonate of potash. It is trie that it may be ob- 
jected that in these decompositions the oxide at the minimum 
is re-oxygenated in the operation at the expense of the nitric acid 
which it converted into nitrous acid; but what weakened this 
objection was the observation I made of the non-action of the 
oxygen gas upon the solution of the-salt. At first it seemed pro- 
bable that, by boiling the lead with the acid nitrate, this metal - 
only took fromh the nitric acid the quantity ef oxygen which forms 
the difference between this acid and the nitfous acid : but the 5°38 
gr. of lead having to absorb 0:41426 of oxygen in order to be 
converted into litharge, whilst the nitric acid of the nitrate could 
only yield 0°1557204 in order to be converted into nitrous acid, 
i concluded that there must have been a decomposition of water, 
or rather that a portion of nitrous acid was itself decomposed. 
This consideration imduced me to make the following experi- 
ment, in order to collect the gas which might have been dis- 
charged. 
12. I put into a matrass the same quantities of lead, acid 
nitrate, and water, which i had employed in the foregoing experi- 
ments. I adapted to it a tube doubly curved, the vertical 
branches of which were very much elongated. ‘One of these 
branches, which entered the upper part of a bel!-glass 15 lines in 
diameter, resembled a funnel. When the apparatus was well 
luted, the water of the bell-glass was three lines below the edge 
of the funnel. According to this arrangement, it was easv to see 
if there was any production of gas. [had given agreat length to 
the vertical branches of the tube, in order that there should be 
the least possible quantity of water to be volatilized ; and I had 
widened the branch which communicated into the bell-glass, in 
order that all the water which was evaporated might be collected 
in the tube, and not mix with that in the bell-glass. I made a 
UF 4h . fire 
