Combinations of different Metals and Chlorine. lgy 
the butter of antimony, or of the sulphat, by a boiling solution 
of carbonat of potash. This oxide, in its purest state, I have 
always found as M, Proust describes it, of a light fawn colour 
before fusion, and afterwards in mass of a gray colour, and of 
a radiated crystalline texture. 100 grains of it that had been 
fused were heated in the state of powder with strong test 
nitric acid in a platina crucible, when nitrous gas ceased to be 
produced, the excess of nitric acid was expelled by a gentle 
heat, and the oxide was heated to dull redness, the increase 
of weight after this, was equal to 10.4 grains ; nitric acid was 
again added and the process repeated, but without any alter- 
ation of weight being produced. Hence as the peroxide con- 
tains 23 per cent, the protoxide seems to contain 15 per cent. ; 
which proportion of oxygene very nearly agrees with that of 
chlorine in the butter of antimony, for antimony being as 42.5, 
the former is to the latter as 7.5 to 34.6, instead of 33.6. I 
put some confidence in this estimate of the proportion of oxy- 
gene in the protoxide, not only on account of its agreement 
with the analysis of the butter of antimony, but because it 
was confirmed on the repetition of the experiment. 
Klaproth concludes from his experiments, that the oxide 
of bismuth, prepared by means of nitric acid, contains 17.7 
per cent, of oxygene, and in consequence this oxide has been 
considered distinct from that which is formed by direct calci- 
nation of the metal, and which contains a much smaller pro- 
portion. But there is reason to believe that this difference 
does not really exist, and that there is only one known oxide 
of bismuth, and that Klaproth's oxide was an hydrated oxide; 
for I have found that 100 grains of bismuth, converted by 
nitric acid into oxide, precisely in the same manner as the 
