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Pi -B62.09 
LIV. Facts and Observations towards a History of the Com~ 
binations of the yellow Oxide of Lead with the Nitric and. 
Nitrous Acids. “By M. Cuevreus *. 
1. M. prousr having observed that the octahedral nitrate 
of lead, when boiled with lamine of this metal, was converted 
into a yellow leafy salt, concluded that the lead was oxidated at, 
the expense of the litharge, the base of the octahedral nitrate, 
and that consequently there was one oxide more at the minimum 
than the latter. Mr. Thomson, in a work upon Lead, resumed 
the examination of the yellow salt described by M. Proust: he 
was led by his experiments to regard if as a salt which differed 
from the octahedral nitrate only by an excess of base. In his 
System of Chemistry, Mr. Thomson renounced this opinien for, 
that of M. Proust; but at the same time he observed that the 
quantity of oxygen in the oxide at the mmimum differed very 
little from that of the litharge. He has not besides added any 
new fact, in order to prove the existence of a new oxide of lead. 
2. At a time when the imagination and experience of che- 
mists carefully examined the laws which preside over the com- 
bination of bodies, I have been surprised at the very little atten- 
tion paid to a salt which might contain a new oxide, and raise to 
four the number of the oxides of a single metal. This considera- 
tion induced me to resolve the following questions : 
Is there an oxide of lead less oxidated than litharge? If this 
oxide exists, what is the quantity of oxygen which it contains? 
and in what ratio is this quantity with that which constitutes the 
yellow, the red, and the puce-coloured oxides of lead? 
3. The first inquiry which occupied my attention, was the 
analysis of the octahedral nitrate of lead; for I could not deter- 
mine the proportion of oxygen which the lead absorbs in order 
for its solution in the nitrate, except by being perfectly ac- 
quainted with the proportions of the elements of this salt, since 
they furnished to the metal the oxygen which it required. I 
took octahedral nitrate, which had been crystallized, twice washed 
it with water, and reduced it to powder. I dried it by exposing 
it for several days to the sun, and afterwards heated it on paper. 
This nitrate was divided into several quantities scrupulously 
weighed, in’ order to be used in the various experiments about 
to be detailed. 
4. I put five grammes of nitrate into a platina crucible 
weighing one ounce four drachms and 43 grams. I exposed 
it to a graduated heat, in order to reduce the salt to its base, and 
withdrew the crucible from the fire when no more nitrous va- 
pours were extricated. I weighed it, and heated it once more red, 
, * Annales du Museum d’ Hist. Nat. ann, x. p. 189. 
7, ; : hot 
