418 Experiments on the Combinations of 
from calomel decomposed by potash, absorbed about 25, of 
oxymuriatic gas, and afforded 724. of oxygen, and currosive 
sublimate was produced in both cases. 
In the decomposition of the white oxide of zinc, oxygen 
was expelled exactly equal to half the volume of the oxy- 
muriatic acid absorbed. In the case of the decomposition 
of the black oxide of iron, and the white oxide of arsenic, 
the changes that occurred were of a very beautiful kind ; 
no oxygen was given off in either case, but butter of arsenic 
and arsenical acid formed in one instance, and the ferru- 
ginous sublimate and red oxide of iron in the other. 
Two grains of white oxide of arsenic absorbed 0°8 of oxy- 
muriatic gas *, 
I doubt not that the same phenomena will be found to 
occur in other instances, in which the metal has compara- 
tively a slight attraction only for oxymuriatic gas, and when 
it is susceptible of different degrees of oxidation, and in 
which the peroxide is used. 
The only instance in which I tried to decompose a com- 
mon metallic oxide, by muriatic acid, was in that of the 
fawu-coloured oxide of tin; water rapidly separated, and 
Libavius’s liquor was formed. . 
From the proportions which may be gained in considering 
the volumes of oxymuriatic gas absorbed by the different 
metals, in their relations to the quantity of oxygen which 
would be reyuired to convert them into oxides, it would 
appear, that in the experiments to which I have referred, 
either one, two, or three proportions of oxymuriatic gas 
sublimate was 78+7 ; the quantity of muriate of silver formed was 102-4; the 
oxide produced front calomel weighed 83 grains; the hora-silver formed 
was 574 grains. I aminclined to put most confidence in the last analyses 5 
but the tenor of both is to show that the quantity of oxymuriatic gas in 
corrosive sublimate is exactly double that in calomel, and that the: orange 
oxide contains twice as much oxygen as the black, the mercury being con- 
sidered as the same in all. The olive colour of the oxide forraed from ca- 
lomel is owing to a slight admixture of orange oxide, formed by the oxygen 
of the water used in precipitation; the tint 1-fiud is almost-black, when a 
boiling solution of potash is used; and trituration with a little orange oxide 
brings the tint to olive, It has been stated, that the olive oxide thrown 
down from calomel by potash is a submuriate; but I have mever been able 
to find a vestige of muriatic acid init when well washed. It is not easy to 
obtain perfect precision in analyses of the oxides of mercury; water adheres 
to the oxides, which cannot be entirely driven off without the expulsion of 
some oxygen. In all my experiments, though the oxides had been heated to 
a temperature above 212, a little dew collected in the neck of the retort, so 
that the 40 grains must have been over-rated. 
* A singular instance of the tendency of the oxide of arsenic to become 
arsenical acid, occurs in its action oa fused hydrat of potash ; the water in 
the hydrat is rapidly decomposed, and arseniuretted hydrogen evolved, and. 
arseniate of potash formed. 
combine 
