on the Chlorides and Oxides of Mercury. 497 
In 93:1 grs. In 100 grs. 
Mercury = 74°09 Mercury = 79°57 
Chlorine = 12°91 Chlorine = 13°87 
B. When white precipitate is heated, there is obtained, 
besides gaseous matter and watery vapour, all the mercury 
and chlorine united as calomel. This mode was now em- 
ployed. A quantity of white precipitate, generally from 15 to 
25 grains, was introduced into a very small tube retort, and 
heated cautiously until all the ammonia constituent had been 
expelled, along with whatever trace of watery vapour ap- 
peared, and the calomel completely sublimed white, which 
by a little care can be accomplished without any loss. Four 
experiments conducted in this way gave results very closely 
agreeing, of which the mean is, 
From 100 of white precipitate, 92-98 of calomel, containing 
Mercury... = 79°14 
Chlorine... = 13°84. 
C. The mercury was obtained in the metallic state by dis- 
solving white precipitate in muriatic acid and decomposing 
by protochloride of tin. ‘The mean result was 77°7 of mer- 
cury from 100 of white precipitate. 
D. White precipitate was dissolved in muriatic acid and 
the liquor decomposed by a current of sulphuretted hydro- 
gen. The sulphuret of mercury was collected on weighed 
filters, dried until it ceased to lose weight, and its quan- 
tity determined. ‘The liquor was evaporated and the quan- 
tity of residual sal ammoniac ascertained. In this way the 
mercury and ammonia are both determined, and the mean re- 
sult is, in 100 of white precipitate, 
Mercury ... = 77:96 
Ammonia... = 7°16. 
E. To obtain another value for the ammonia the following 
processes were used in addition. When white precipitate is 
boiled with a solution of sulphuret of barium, the mercury is 
all converted into sulphuret, there are formed chloride and 
oxide of barium, and ammonia is disengaged. The gaseous 
ammonia was passed over into a vessel of dilute muriatic acid, 
and the sal ammoniac obtained dry by evaporation. Ifa so- 
lution of iodide of potassium be digested on white precipi- 
tate, the quicksilver is converted into biniodide; and there 
being formed chloride and oxide of potassium, ammonia is 
set free, and its quantity determined as above. The mean of 
the results is that 100 of white precipitate contain 6°53 of 
ammonia. 
I’. In all theories of the composition of white precipitate 
Third Series. Vol. 8 No. 49. June 1836. Re OF 
