Mr. Davy's Experiments on the 
posed by potash, absorbed about of oxymuriatic gas, and 
afforded of oxygene, and corrosive sublimate was pro- 
duced in both cases. 
In the decomposition of the white oxide of zinc, oxygene 
was expelled exactly equal to half the volume of the oxv- 
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 oxy- 
gene was given off in either case, but butter of arsenic, and 
arsenical add formed in one instance, and the ferruginous sub- 
limate, and red oxide of iron in the other. 
care. I decomposed ioo grains of corrosive sublimate, by 90 grains of hydrat of 
potash. This afforded 79.5 grains of orange coloured oxide of mercury, 40 grains of 
which afforded 9.15 cubical inches of oxygene gas; the muriate of silver formed from 
the 100 grains was 102.5. 
100 grains of calomel, decomposed by 90 grains of potash, afforded 82 grains of 
olive coloured oxide of mercury, of which 40 grains gave by decomposition by heat 
4.8 cubical inches of oxygene. The quantity of horn-silver formed from the 100 
grains was 58.75 grains. 
In the second analysis, the quantity of oxide obtained from corrosive sublimate was 
78.7 ; the quantify of muriate of silver formed was 103.4; the oxide produced from 
calomel weighed 83 grains ; the horn-silver formed was 57! grains. I am inclined to 
put most confidence in the last analyses ; but the tenor of both is to shew that the quan- 
tity of oxymuriatic gas in corrosive sublimate, is exactly double that in calomel, and 
that the orange oxide contains twice as much oxygene as the black, the mercury being 
considered as the same in all. The olive colour of the oxide formed from calomel, 
is owing to a slight admixture of orange oxide, formed by the oxygene of the water 
used in precipitation; the tint I find 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 sub- 
muriate ; but I have never been able to find a vestige of muriatic acid in it 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 oxygene. 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. 
