Origin. - The knowledge of this drug antedates the Christian era. It is found in Spain, Austria, Peru, and China, but is obtained principally from New Almaden, California. It occurs to some extent in the metallic state in the form of minute or large globules; also in combination with oxygen, chlorine, selenium, etc.; but the principal ore from which it is extracted is cinnabar.

Description and Properties. - A shining, silver-white metal, without odor or taste. It is liquid at the ordinary temperature, and easily divisible in spherical globules; but when cooled to - 39.38o C. ( - 38.88 F.J, it forms a ductile, malleable mass. Specific gravity, 13.535 at 250 C. (770 F.).

Insoluble in the ordinary solvents, also in concentrated hydrochloric acid, and, at common temperatures, in sulphuric acid, but dissolving in the latter when boiled with it, and readily and completely soluble in nitric acid. Mercury should be kept in strong, well-stoppered bottles.

Dose. -Mercury is seldom given internally except in the modified form of blue pill.

Official Derivatives

Hydrargyrum Ammoniatum - Hydrargyri Ammoniati - Ammoniated Mercury (U. S. P.). - Origin. - Prepared by mixing solutions of ammonia and corrosive mercuric chloride. Filter and wash the precipitated ammoniated mercury. It should contain not less than 78 per cent., nor more than 80 per cent., of metallic mercury.

Description and Properties. - White, pulverulent pieces, or white, amorphous powder, without odor, and having an earthy, and afterward styptic and metallic taste. Permanent in the air. Almost insoluble in water or in alcohol. It should be kept in well-stoppered bottles, protected from the light. Used externally.

Unguentum Hydrargyri Ammoniati - Unguenti Hydrargyri Ammoniati -Ointment of Ammoniated Mercury. - Formula: Ammoniated mercury, 10; white petrolatum, 50; hydrous wool-fat, 40. For external use.

Hydrargyrum cum Creta - Hydrargyri cum Creta - Mercury with Chalk (U. S. P.). - Origin. - Obtained by trituration of mercury, prepared chalk, clarified honey, and water.

Description and Properties. - A light-gray, rather damp powder, free from gritti-ness, without odor, and having a slightly sweetish taste. It contains 38 per cent. of mercury. This preparation should be kept in well-stoppered bottles, protected from light.

Dose, 3-10 grains (0.18-0.6 Gm.) [4 grains (0.25 Gm.), U. S. P.].

Massa Hydrargyri - Massse Hydrargyri - Mass of Mercury (U. S. P.). (Pilula Hydrargyri - Blue Mass - Blue Pill). - Composed of mercury, glycyr-rhiza, althaea, glycerin, and honey of rose.

Dose, 1/2-10 grains (0.03-0.6 Gm.) [4 grains (0.25 Gm.), U. S. P.].

Unguentum Hydrargyri - Unguenti Hydrargyri - Mercurial Ointment (U. S. P.). - Composition: Mercury, lard, suet, and oleate of mercury. Used externally.

Unguentum Hydrargyri Dilutum - Unguenti Hydrargyri Diluti - Blue Ointment (U. S. P.). - This preparation contains 67 per cent. of unguentum hydrargyri, which is called mercurial ointment. Heretofore "Blue Ointment" and " Mercurial Ointment" have been synonymous. Mercurial ointment contains about 50 per cent. of metallic mercury, while blue ointment contains about 33.5 per cent.

Emplastrum Hydrargyri - Emplastri Hydrargyri - Mercurial Plaster (U. S. P.). - Composition: Mercury, oleate of mercury, hydrous wool-fat, and lead plaster. Used externally.

Hydrargyri Chloridum Corrosivum - Hydrargyri Chloridi Corrosivi - Corrosive Mercuric Chloride (U. S. P.) (Corrosive Chloride of Mercury - Corrosive Sublimate).- Origin. - Prepared by heating a mixture of mercuric sulphate, sodium chlorate, and manganese dioxide. The corrosive chloride sublimes and is condensed. It should contain not less than 99.5 per cent. of pure mercuric chloride.

Description and Properties. - Heavy, colorless, rhombic crystals or crystalline masses; odorless and having an acrid and persistent metallic taste. Permanent in the air. Soluble in 13 parts of water, in 3 parts of alcohol, in 2 parts of boiling water, in 1.2 parts of boiling alcohol, in 4 parts of ether, and in about 14 parts of glycerin. It should be kept in well-stoppered bottles.

Dose. - 1/64-1/8 grain (0.001-0.008 Gm.) [1/20 grain (0.003 Gm.), U. S. P.].

Hydrargyri Chloridum Mite - Hydrargyri Chloridi Mitis - Mild Mercurous Chloride (U.S.P.) (Calomel - Mild Chloride of Mercury). - Origin. - Obtained by triturating mercuric sulphate, mercury, sodium chloride, and boiling distilled water. Sublime, and wash the sublimed calomel with boiling distilled water. It should contain not less than 99.5 per cent. of pure mercurous chloride.

Description and Properties. - A white, impalpable powder, becoming yellowish-white on being triturated with strong pressure. It is odorless and tasteless, and permanent in the air. Insoluble in water, alcohol, or ether, and also in cold diluted acids. When strongly heated it is wholly volatilized, without melting. Calomel should be kept in dark, amber-colored bottles.

Dose. - 1/32-10 grains (0.002-0.6 Gm.) [1-2 grains (0.065-0.125 Gm.), U. S. P.].

Pilulae Catharticae Compositae - Pilulas (acc.) Catharticus Compositas -Compound Cathartic Pills. - Dose, 1 to 3 pills.

Hydrargyri Iodidum Flavum - Hydrargyri Iodidi Flavi - Yellow Mercurous Iodide (U.S.P.) (Hydrargyri Iodidum Viride - Protiodide of Mercury - Yellow (or Green) Iodide of Mercury). - Origin. - Prepared by mixing solutions of potassium iodide and mercurous nitrate with nitric acid and distilled water. The precipitate is washed and dried. It should contain not less than 99.5 per cent. of pure mercurous iodide.

Description and Properties. - A bright-yellow, amorphous powder, odorless and tasteless. By exposure to light it becomes darker in proportion as it undergoes decomposition into metallic mercury and mercuric iodide. Almost insoluble in water, and wholly insoluble in alcohol or ether. It should be kept in dark, amber-colored vials, with the least possible exposure to light.