4138. Chloride of Mercury

4138.      Chloride of Mercury. This preparation is usually known as calomel. Boil, by means of a sand-bath, 24 troy ounces mercury with 3G troy ounces sulphuric acid, until a dry white mass is left. Rub this, when cold, with 24 ounces mercury in an earthenware mortar until thoroughly mixed; add 18 troy ounces chloride of sodium, triturate until the globules of mercury cease to appear, and sublime the mixture. Reduce the sublimate to a very fine powder and wash it with boiling distilled water until the washings afford no precipitate with water of ammonia, and dry it. (U. S. Ph.)

4139. Bichloride of Mercury

4139.     Bichloride of Mercury. The corrosive sublimate of the drug stores. Boil 24 troy ounces mercury in 36 troy ounces sulphuric acid, by means of a sand-bath. When cold, rub the dry white mass with 18 troy ounces chloride of sodium in an earthenware mortar; then sublime with a gentle heat. ( U. S. Ph.)

4140. White Precipitate

4140.    White Precipitate. This is the ammonio-chloride of mercury, and is prepared by dissolving, with heat, 6 ounces bichloride of mercury (corrosive sublimate) in 3 quarts distilled water; when cool, add 8 fluid ounces liquor of ammonia, frequently shaking it. Wash the precipitate with water, and dry it. It is used to make an ointment for skin diseases ; also to destroy small vermin.

4141. Bed Precipitate

4141.    Bed Precipitate. Red oxide or binoxide of mercury is now used in medicine as an escharotie, also to induce salivation. Dissolve 4 ounces bichloride of mercury in 6 pints water; add 28 fluid ounces liquor of ammonia; wash the precipitate in distilled water, and dry by a gentle heat.

4142. Chloride of Mercury and Ammonia

4142.    Chloride of Mercury and Ammonia. This is obtained by triturating together equal parts of bichloride of mercury and sal-ammoniac. This addition of sal-ammoniac renders the corrosive sublimate more soluble in water, for use in lotions and injections.

4143. Black Precipitate

4143.     Black Precipitate. Protoxide of mercury is obtained by agitating together 1 ounce calomel with 1 gallon lime-water; decanting the clear liquid after subsidence, and washing the sediment with distilled water, after which it is dried on bibulous paper.

4144. Protonitrate of Mercury

4144.    Protonitrate of Mercury. Mix together in a wide-bottomed glass vessel, equal parts of quicksilver and nitric acid (specific gravity 1.32); after digestion for 24 hours in a cool place, remove the crystals that have formed, wash them with a little nitric acid, drain them, and keep from the air in a stoppered bottle. (Paris Codex.)

4145. Tests for the Salts of Mercury

4145.    Tests for the Salts of Mercury. The salts of mercury are all volatilized at a dull red heat - give a white precipitate with prussiate of potash, a black one with sulphuretted hydrogen and hydrosulphurets, an orange-yellow one with gallic acid, and with a plate of polished copper, a white coat of metallic mercury.

Solutions of the protosalts of mercury yield a grey or black precipitate with alkalies, a yellowish or greenish-yellow one with iodide of potassium, a white one with muriate of soda.

Solutions of the persalts of mercury yield with caustic alkalies, yellowish or red precipitates; with alkaline carbonates, a brick-red one; with iodide of potassium, a scarlet one.