CHLORIDES AND OXIDES OF MERCURY. 
257 
Of the pnwder formed by the action of ivater on the white 
precipitate. 
It is the general belief that by the action of boiling water 
the white precipitate is entirely converted into peroxide of 
mercury: I have never succeeded in performing this experi- 
ment; on the contrary, I have found that boiled in water it 
becomes canary yellow, granular and easy to dry. This 
powder is not totally insoluble in water; heated it gives 
off nitrogen, ammonia, water, and a m.ixture of calomel and 
mercury sublimed. It is readily soluble in nitric and chloro- 
hydric acids. The alkalies only alter its colour; treated by 
the iodide of potassium ammonia is disengaged, and a brown 
powder is produced. 
The precipitate from 100 parts of sublimate was thus treat- 
ed : when it had become yellow, it was thrown on a filter 
and washed, and the liquid and washings precipitated by ni- 
trate of silver. I give here the mean of several experiments: 
Yellow powder 83.83, chlorine in the liquid 18.89. 
We thus see that three parts of the chlorine of the subli- 
mate remains in the liquid, and the fourth and all the mercury 
in the yellow powder. 
When white precipitate, already prepared, is boiled in 
water, a yellow powder is obtained and the liquid above it 
contains sal ammoniac alone. This reaction enables us to as- 
certain the composition of the yellow powder. The chlorine 
of the sal ammoniac was precipitated by nitrate of silver, and 
its weight determined. Four experiments of this kind gave 
the following as the composition of the yellow powder: 
Mercury, 78.60 
Chlorine, 7.56 
100 grains of white precipitate, boiled in water, gave 91.15 
of yellow powder, and the liquid evaporated to dryness gave 
10.23 of sal ammoniac. 
Jiction of an excess of alkali on the white precipitate. 
Grouvclle and other chemists assort that an excess of am* 
