2. (Basic.) HgSO4,2HgO. Syn. Tribasic sulphate of mercury, Turpeth mineral, Turbith m., Queen’s yellow, Subsulphate of mercury†, Tribasic persulphate of m.; Hydrargyri subsulphas, H. s. flavus, Terpethum minerale, L.—a. Dissolve mercury in an equal weight of sulphuric acid by boiling them to dryness, fling the mass into
hot water, and wash and dry the resulting yellow powder.
b. (Ph. D. 1826.) Mercuric sulphate, 1 part; warm water, 20 parts; triturate together in an earthen mortar, wash well with distilled water, drain, and dry it.
Prop., &c. A heavy, lemon-yellow powder, soluble in 2000 parts of cold, and about 600 parts of boiling water. By long-continued washing with very hot water it loses all its remaining acid, and is at length converted into red oxide of mercury.—Dose. As an alterative, 1⁄8 to 1⁄2 gr.; as an emetic, 3 to 5 gr.; as an errhine, 1 gr.; mixed up with a pinch of liquorice powder or fine snuff. It is a powerful poison, and one of the least useful of the mercurial preparations.
Obs. The temperature of the water employed to decompose the neutral sulphate influences the shade of colour of the resulting salt in a similar manner to that pointed out under the nitrate. It is now superseded as a pigment by chrome yellow and orpiment, which are not only more beautiful, but cheaper preparations.
Mercuric Sulphide. HgS. Syn. Protosulphide of mercury, Red sulphuret of mercury, Factitious cinnabar, Vermilion, Sulphuret of mercury, Sulphide of m., Bisulphuret of m.†; Hydrargyri bisulphuretum (Ph. B. & Ph. L.), Cinnabaris (Ph. E.), H. sulphuretum rubrum. L. Prep. (Ph. L.) Quicksilver, 24 oz.; sulphur, 5 oz.; melt together, and continue the heat till the mixture swells up, then cover the vessel, remove it from the heat, and when cold, powder and sublime it. (Ph. B.) Quicksilver, 2 lbs.; sulphur, 5 oz.
Prop., &c. Mercuric sulphide has a dark-red semi-crystalline appearance in the mass, but acquires a brilliant scarlet colour by powdering. It is tasteless, odourless, and insoluble. It is chiefly used as a pigment; but it is occasionally employed in medicine as a diaphoretic and vermifuge, and in some cutaneous diseases and gout.—Dose, 10 to 30 gr.; as a fumigation, about 1⁄2 dr. is thrown on a plate of iron heated to dull redness. For the last purpose it is inferior to mercurous oxide, owing to the more irritating nature of its vapour.
Tests. Mercurous salts. Sulphuretted hydrogen and ammonium sulphide give black precipitates, insoluble in dilute acids, ammonium sulphide, potassium cyanide, and hot nitric acid, but slightly soluble in sodium sulphide, and decomposed by nitro-hydrochloric acid.
Potassium hydrate and ammonia give black grey or black precipitates, which are insoluble in excess of the precipitant.
Hydrochloric acid and the soluble metallic chlorides occasion a precipitate, which assumes the form of a very fine powder of dazzling whiteness, insoluble in excess, but soluble in aqua regia and liquid chlorine. Potassium