§ 866 .] MERCURY. 681 
water into the very slightly soluble basic salt of mercury, known as 
Turbith mineral , HgS0 4 2Hg0. 
Turbith, or Turpeth, Mineral is contained in the French pharma¬ 
copoeia, HgS0 4 2Hg0 ; Hg, 82-4 per cent. ; specific gravity, 8-319. It 
requires for solution 2000 parts of cold and 600 of boiling water, but 
dissolves with tolerable ease in hydrochloric acid. 
Hahneman’s Soluble Mercury (Hydrargyrum solubile Hahnemanni) 
is official in the Dutch pharmacopoeia. As found in commerce, it con¬ 
tains metallic mercury, nitric acid, and ammonia. The mercury should 
be in the proportion of 86-33 per cent., the ammonia 2-44 per cent. 
Crystallised Nitrate of Mercury (Hydrargyrum nitricum oxidu- 
latum) is official in the pharmacopoeias of Germany, Switzerland, and 
France. The salt is in white crystals, giving the reactions of nitric acid 
and mercury, decomposed by the addition of water, but fully soluble in 
water, if first moistened with nitric acid. The formula of the neutral 
salt is Hg2N0 3 Hg02H 2 0, which requires 69-4 per cent, of mercury. 
An acid solution of mercuric nitrate is official. 
An Ointment of Nitrate of Mercury (Unguentum hydrargyri 
nitratis) —often called citrine ointment—is contained in the B.P. ; it is 
made with 10 grms. of mercury, 40 grms. of lard, 70 grms. olive oil, and 
30 millilitres of nitric acid. There is also a diluted mercuric nitrate 
ointment made by mixing 80 grms. of soft yellow paraffin with 20 grms. 
of mercuric nitrate ointment. 
A Chloride of Mercury and Quinine exists in commerce, prepared 
by mixing 1 part of corrosive sublimate in solution with 3 parts of 
quinine chloride, evaporating, and crystallising. 
Cyanide of Mercury, HgCy, is contained in the French pharma¬ 
copoeia. It occurs in small, colourless, prismatic crystals, easily soluble 
in water. If to the solution chloride of tin be added, a black precipitate 
of reduced*metal and stannous oxide is thrown down, and the odour of 
prussic acid is developed. 
Mercuric Sulphide (Sulphide of Mercury, Cinnabar, Vermilion) is 
official in Germany, the Netherlands, and France ; HgS = 232 ; specific 
gravity, solid, 8-2 ; Hg, 86-21 per cent., O, 13-79 per cent. For medicinal 
purposes it is made artificially. It is a beautiful red powder insoluble in 
all alkaline and all acid liquids, with the exception of aqua regia. The 
solution gives the reactions of a sulphide and mercury. On heating, it 
must burn away entirely without residue ; adulterations or impurities 
are—minium, lead, copper, and other metals. The detection of minium 
is conveniently executed in the dry way. Pure cinnabar, when heated 
in a matrass, gives a black sublimate, which becomes red on friction. 
If minium is present, sulphide of lead remains as a residue, and may be 
recognised on coal ; the same remark applies to sulphide of antimony. 
If it be desired to take the percentage of mercury in cinnabar, equal 
