Preparations. - 1. Pilulae Cathartiae Compositae, 1 gr. (.06 Gm.). Dose, 1-3 pills.

Unoff. Preps.: Pulvis Hydrargyri Chloridi Mitis et Jalapae, mild mercurous chloride 34 p. c, + jalap 66. Unguentum Hydrargyri Subchloridi (Br.), 20 p. c. Lotio (Hydrargyri) Nigra, .875 Gm., water 1.5, sol. calcium hydroxide q. s. 100.

Properties and Uses. - Purgative, anthelmintic, alterative, chola-gogue. Most valuable mercury salt; lessens biliary secretion, causes salivation. Used for syphilis, typhoid, yellow and remittent fevers, inflammatory diseases, pericarditis, endocarditis, pleurisy, pneumonia, meningitis, hepatitis, dropsy, articular rheumatism, dysmenorrhoea, iritis, jaundice, pseudomembranous laryngitis, bronchitis, dysentery, cholera, lumbricoid worms. With lime water have black wash (lotio nigra, aqua phagedaenica nigra), 3/4 p. c, used locally to syphilitic ulcers, etc. An ointment (10 p. c.) useful in scaly skin eruptions, condylomata, corneal ulcers, maggots.

Hydrargyri Oxidum Rubrum. Red Mercuric Oxide, HgO. - (Syn., Hydrarg. Oxid. Rub., Red Precipitate, Hydrargyri Nitrico-oxidum, Mercurius Corrosivus (Praecipitatus) Ruber, Peroxide of Mercury, Oxydum Hydrargyricum; Fr. Deut-oxyde (Peroxyde) rouge de Mercure, Oxyde mercurique, Precipite rouge, Poudre de Jean de Vigo; Ger. Hydrargyrum oxydatum (rubrum), (Rotes) Quecksilberoxyd, Roter Pracipitat (Quecksilber Pracipitat).)

Manufacture: Dissolve mercury in nitric acid, then either heat alone or triturate this dried mercuric nitrate with mercury and heat - (1) Hga + 8HNO3 = 3Hg(NO3)2 + 2NO + 4H2O. (2) 2Hg(NO3)2 + heat = 2HgO + 4NO2 + O2, or 2Hg(NO3)2 + Hg2 + heat = 4HgO + 2N2O4. It is in heavy orange-red crystalline scales or powder, acquiring yellow color when finely divided; odorless; metallic taste; permanent; soluble in diluted nitric acid (clear solution), hydrochloric acid, 1 in 10 (faint opalescence); insoluble in alcohol, almost insoluble in water; contains 99.5 p. c. of pure salt. Tests: 1. Heat to 400° C. (750° F.) - dark violet, black, but original color on cooling; at red heat - decomposes completely into oxygen and metallic mercury, finally volatilizes with residue .2 p. c. 2. Dissolve .5 Gm. in 25 Ml. (Cc.) of hydrochloric or nitric acid - not more than slightly turbid. Impurities: Yellow mercuric oxide, nitrate. Should be kept dark, in well-closed containers. Dose, gr.1/10 (-006 Gm.), in syphilis.

Preparations. - (Unoff.): Unguentum Hydrargyri Oxidi Rubri, official 1830-1910, 10 p. c: red mercuric oxide 10 Gm., hydrous wool fat 40 Gm., petrolatum 40 Gm., water 10, avoid metallic utensils. Liquor Hydrargyri Nitratis: red mercuric oxide 40 Gm., nitric acid 45 Gm., distilled water 15 Gm.

Properties and Uses. - Red Oxide - not used much internally, but mostly externally as stimulant, escharotic; ulcers, wounds, indolent syphilitic sores, condylomata, corneal opacity, granular eyelids, pannus, ozaena, in powder or ointment. The yellow oxide has nearly replaced this salt. Mercuric Cyanide - used instead of corrosive sublimate for constitutional syphilis, diphtheria (gargle 1 in 10,000). Liquor Hydrargyri Nitratis - used as a caustic for cancers, lupus, ulcerations of uterus, chancres, acne, boils, syphilitic sores, very poisonous, which may result even from skin absorption.

Allied Salts:

1. Hydrargyri Subsulphas Flavus. Yellow Mercuric Subsidphate (Turpeth Mineral), Hg(HgO)2SO4, official 1830-1900. - Obtained by dissolving mercury 100 Gm. in sulphuric acid 30 Ml. (Cc.) + distilled water 15 Ml. (Cc), adding gradually nitric acid 25 Ml. (Cc.) + distilled water 25 Ml. (Cc), evaporating to dryness, powdering, and adding it gradually to boiling distilled water 2000 Ml. (Cc), boiling 10 minutes (to convert normal into basic sulphate, the acid sulphate 51 remaining in solution), washing and drying precipitate - Hg3 + 3H2SO4 + 2HNO3 = 3HgSO4 + 2NO + 4H2O. It is a heavy lemon-yellow powder, odorless, tasteless, permanent, soluble in HNO3, HC1, water (2000), boiling water (600), insoluble in alcohol. Impurities: Mercurous salt, lead; should be kept in the dark, in well-stoppered bottles. Alterative, emetic, errhine, irritant poison, salivates; croup, spasmodic laryngitis. Dose, gr. 2-3 (.13-.2 Gm.), for child two years old, repeated in 15 minutes; as alterative for adult, gr. 1/4-1/2 (.016-.03 Gm.); emetic, gr. 2-5 (.13-.3 Gm.); errhine, gr. 1 (.06 Gm.) + starch q. s.; gr. 60 (4 Gm.) have killed.

2. Hydrargyri Sulphidum Rubrum. Red Sulphide of Mercury. Cinnabar, HgS, official 1880-1890. - Obtained by gradually adding mercury (40) to melted sublimed sulphur (8), constantly stirring; the mass is heated until it begins swelling, then cooled under close cover, rubbed into powder, and sublimed. It is a mercuric salt, and occurs in brilliant dark red crystalline masses or bright scarlet powder, odorless, tasteless, permanent, insoluble in water, alcohol, nitric or hydrochloric acid, soluble in nitromuriatic acid, sp. gr. 8.12. Impurities: Arsenic, antimony, chromates, iodides, sulphides, red oxide of mercury, red oxide of lead. By fumigation as a sialagogue in syphilitic affections.

3. Hydrargyri Cyanidum. Mercuric Cyanide, Hg(CN)2, official 1830-1900. - Obtained by dissolving mercuric oxide in hydrocyanic acid, the latter being prepared from potassium ferrocyanide and sulphuric acid - HgO + 2HCN = Hg(CN)2 + H2O; usually by passing HCN gas into mercuric oxide in water, when soluble Hg(CN)2 is formed, evaporating to crystallize. It is in white prismatic crystals, odorless, bitter, metallic taste, darkens by light, exceedingly poisonous, soluble in water (12.8), alcohol (12). Impurities: Mercuric chloride, etc.; should be kept in well-stoppered bottles. Dose, gr. 1/16-1/8 (.004-.008 Gm.).

4. Mercuric Sulphate-Ethylenediamine. Subla-mine, HgSO42C2H4(NH2)2 + 2H2O.

Manufacture: By combining one molecule of mercuric sulphate and two molecules of ethylene-diamine. Occurs in white alkaline needles, soluble in water, glycerin (10), sparingly in alcohol; contains 44 p. c. of mercury; does not precipitate albumin, is incompatible with sodium chloride, and should not be exposed to the air.

Properties and Uses. - Disinfectant, similar to mercuric chloride, but is more soluble and penetrating, and less irritating; dermatology, gynecology, ophthalmology, otology, in solutions - 1:1000,3000, 5000, the weaker for skin disinfection, the stronger for irrigations of the bladder, etc.; 3-4 p. c. solution may be injected into gluteal muscles for syphilis.

Fig. 465.   Mercuric cyanide crystal.

Fig. 465. - Mercuric cyanide crystal.