Intelligence and Miscellaneous Articles. 497 
represented byB12O0+#. Thus the twooxidesof bismuth, says M. Frémy, 
have evidently for their formule Bi? 03, Bi? O41. This result agrees 
perfectly with the experiments of M. Jacquelain, and the late ex- 
periments of M. Regnault on the specific heat of bismuth, and that 
of its combinations.—Journal de Pharmacie, Janvier 1843. 
ON THE OXIDES OF LEAD, PLOMBIC ACID AND THE PLOM- 
BATES. 
M. Frémy observes, that the protoxide of lead dissolves in the 
alkalies, and forms crystalline compounds with some bases; but the 
hydrate of this oxide, under the influence of the alkalies, is dehydrated 
as readily as the hydrates of the oxides of bismuth and tin; so that 
when the hydrated protoxide of lead is boiled in a solution of alkali not 
sufficient to dissolve it, the hydrate is converted into perfectly crystal- 
lized anhydrous oxide of lead; it is the oxide which M. Payen had 
previously obtained by treating acetate os lead with ammonia. This 
oxide, he has also remarked, may change its colour when strongly 
heated, and the same effect may be produced by friction. 
The solutions of oxide of lead in the alkalies deposit by evapora- 
tion anhydrous crystals of oxide of lead, which differ from the pre- 
ceding by the facility with which they dissolve even in weak alka- 
line solutions. 
M. Frémy states, that the observations which he has made re- 
specting the protoxide of lead, prove that it may combine with bases 
when hydrated, but that, like the protoxide of tin, it is dehydrated 
under the influence even of the alkalies which hold it in solution, 
and that it then precipitates in the anhydrous crystalline state, pos- 
sessing different properties according to the different circumstances 
which determine its precipitation: 
The puce or peroxide of lead has hitherto been considered as a 
neutral body, incapable of combining with any other substance, and 
all chemists have considered minium as a compound of protoxide and 
peroxide of lead. According to M. Frémy, the peroxide of lead is 
a true acid, which is capable of combining with bases to form well- 
defined and often crystallized salts, the general formula of which is 
Pb O02, MO. He proposes then to give the second compound of lead 
with oxygen the name of plombic acid, then reserving the name of 
plombites for the salts formed by the combination of protoxide of 
lead with metallic oxides. 
The plombates are prepared in the dry way: the plombates of 
potash and soda are obtained by heating peroxide of lead (plom- 
bic acid) with excess of these alkalies ; the mass is to be treated with 
water ; the liquor by spontaneous evaporation yields perfectly de- 
fined crystals of the alkaline plombate. These salts may also be 
procured by heating in the air protoxide of lead with the alkali, 
which becomes peroxide and oxidizes the protoxide of lead. 
The plombates of potash and soda crystallize perfectly in a weak 
alkaline solution, but are decomposed by pure water ; consequently 
when a solution of a plombate is diluted with a large quantity of 
Phil. Mag. 8.3. Vol. 22. No. 147. June 1843. 2 L 
