CHLORIDES AND OXIDES OF MERCU!lY. 
255 
These results give us for 100 of precipitate a mean of 92.98 
of calomel, or 
(Hg79.144-Chl3.84.) 
3. The calomel treated by chemical agents, to obtain its 
mercury, gave in the first experiment 77.3 per cent, of preci- 
pitate, in a second 7S.1 thus giving a mean of 77.7 per cent. 
4. 105.40 of white precipitate dissolved in muriatic acid 
and precipitated by sulphuretted' hydrogen, gave a black 
precipitate, which was collected on a weighed filter and well 
washed; the washings were added to the liquid, the whole 
evaporated to dryness and the residue weighed: the results 
were 95.23 of bisulphuret of mercury, or mercury 82.17 + 
sulphur 13.06; and 23.57 of sal ammoniac, or muriatic acid, 
16.04 4- ammonia 7.55; or still better, 77.96 mercury + 7.16 
ammonia (per cent.) 
5. 100 grains of the precipitate were put into a phial to 
which a bent tube was adapted; this tube was placed in weak 
muriatic acid; a solution of sulphuret of barium was then 
poured into the phial; heat disengaged ammonia and water; 
the liquid into which these passed was evaporated to dryness; 
there remained 21.57 grains, of sal ammoniac or muriatic 
acid 14,85, ammonia 6.72. The iodide of potassium used in 
the same way gave for 100 grains 19.83 of sal ammoniac. 
6. It has been supposed that the white precipitate contains 
a quantity of oxygen sufficient to peroxidize all the mercury. 
Thus far my researches have not led me to this conclusion; 
for heated in a tube it gives off* no oxygen; the oxygen, if 
there be any, must therefore form water at the expense of the 
ammonia. To arrive at some conclusion I collected the water, 
to determine by its weight the quantity of oxygen in the pre- 
cipitate; some of this was placed in a small weighed retort, to 
which was fixed a tube containing potassa and unslacked lime, 
which communicated by another tube with the mercurial 
trough; the retort was weighed after the introduction of the 
precipitate, as also the drying tube. The retort was heated 
until the calomel sublimed. The whole of the water was ab- 
