ON HYDRARGYRUM CUM CRETA. 
115 
all the matter soluble in that menstruum was removed, when 
the whole was thrown on a weighed filter and the insoluble 
residue washed with distilled water and dried. The pre- 
sence of bichloride of mercury in the colorless filtered solu- 
tion was indicated by its affording a black precipitate with 
hydrosulphuret of ammonia, a yellow precipitate with solu- 
tion of potassa, a scarlet precipitate with iodide of potassium 
soluble in an excess of the precipitant, and a white precip- 
itate with ammonia. The whole of the liquid was 
precipitated with the latter reagent and the precipitate when 
washed and dried, weighed 16 grains, representing 17.02 
grains of corrosive sublimate in the solution, or 13.68 grains 
of red oxide in the hydrarg. cum creta experimented on. 
The insoluble residue left by the dilute hydrochloric acid 
weighed 11.5 grains. It had a bluish gray color without 
exhibiting any globules of free mercury. This was boiled 
in solution of potassa, which instantly changed its color to 
black. This liquid filtered off from the black powder was 
saturated with nitric acid and a slight excess of nitrate of 
silver added, which produced a white precipitate soluble in 
ammonia. This was collected on a weighed filter, washed, 
dried, and weighed, amounting to 1.75 grains, representing 
.431 grain of chlorine, or 2.9 grains of calomel which was 
produced from 2.526 grains of black oxide of mercury exist- 
ing in the mercurial powder analysed. The black powder 
resulting in the last experiment was treated with acetic acid 
until the black oxide of mercury was removed, and the filter 
washed and dried. The residue of metallic mercury par- 
tially revived, weighed 6.50 grains. 
It follows from these results that the specimen of " mer- 
cury with chalk " examined, contains of 
Deutoxide of Mercury, 
Protoxide of Mercury, 
Metallic Mercury, 
per cent. 
22.80 
4.21 
10.83 
equal to 
21.25 of metal 
4.05 " 
10.83 « 
36.13 
