PREPARATIONS OF MERCURY. 113 



and chloride of sodium. At first, it is in white, semi-transparent 

 masses ; soluble in water and alcohol ; taste, metallic and styptic ; 

 very poisonous; best antidote is albumen ; not much used internally; 

 not so liable to salivate as calomel ; externally applied, it is escha- 

 rotic ; a weak solution, or ointment is employed in venereal sore 

 throat and cutaneous diseases. 



Black Oxide of Mercury — {Hydr. Oxidum Nigrum, U. S.) — 

 Chemically, a protoxide,- made by adding calomel to lime-water, 

 or a solution of potash ; colour, black ; used only as a wash for 

 chancre. 



Red Oxide of Mercury — {Hydr, Oxidum Rubrum, U. S.) — Che- 

 mically, a binoxide; common name, Red precipitate ; made by heat- 

 ing the nitrate ; occurs in small, shining, red crystals ; never used 

 internally; but externally, as a stimulant for old and indolent ulcers ; 

 also, for psorophthalmia, in the form of ointment. 



Iodide of Mercury — {Hydrarg. lodidum, U. S.) — Chemically, a 

 protiodide; made by rubbing up mercury and iodine together; colour, 

 greenish-yellow ; used in secondary syphilis ; dose, one grain, gra- 

 dually increased. 



Biniodide of Mercury— {Hydrarg. lodidum Rubrum, U. S.) — 

 Prepared, as the former, with double the quantity of iodine ; colour, 

 brilliant red ; used as an ointment in skin diseases. 



Red Sulphuret of Mercury — {Hydr. Sulphur etum Rubrum, U. S.) 

 — Common name, Cinnabar; found native; made, by heating to- 

 gether mercury and sulphur; colour, fine red; powder is called 

 vermilion, — used for fumigation. 



Black Sulphuret of Mercury — {Hydr. Sulphuretum Nigrum, U. 

 S.) — Old name, Ethiops mineral; prepared by rubbing sulphur and 

 mercury together in a mortar ; colour, black ; scarcely ever used 

 at present. 



Yellow Sulphate of Mercury — {Hydr. Sulphas Flavus, U. S.) — 

 Common name, Turpeth mineral; made by the action of boiling 

 water on the bisulphate ; the yellow subsulphate precipitates ; very 

 little used ; emetic, in the dose of 5 grains. 



Nitrate of Mercury — {Hydrarg. Nitras, U. S.) — Used only in 

 the form of ointment, — called citrine ointment. This is of a fine 

 citron colour, when first made, but spoils by being kept; much used 

 in skin diseases, and as a stimulant to ulcers. 



Ammoniated Mercury — {Hydrargyrum Ammoniatum, U. S.) — 

 Common name, WJdte precipitate ; made by adding the solution of 

 ammonia to a solution of corrosive sublimate ; occurs in white 

 masses, without odour; used only as an ointment for cutaneous 



