Granulated; Ferri sulphas granulata, L. (B. P.) A solution of iron wire, 4 oz., in sulphuric acid, 4 fl. oz., diluted with water, 11⁄2 pint, after being boiled for a few minutes, is filtered into a vessel containing rectified spirit, 8 fl. oz., and the whole stirred until cold, when the granular crystals are collected on a filter, washed with rectified spirit, 2 fl. oz., and dried, first by pressure between bibulous paper, and next beneath a bell-glass over sulphuric acid, after which they are put into a stoppered bottle, to preserve them from the air.
Prop., &c. Ferrous sulphate forms pale bluish-green rhombic prisms, having an acid, styptic taste, and acid reaction; it dissolves in two parts of cold and less than one part of boiling water; at a dull-red heat it suffers decomposition; sp. gr. 1·82. It is perfectly soluble in water; a piece of iron put into the solution should not be covered with metallic copper. By exposure to the air it effloresces slightly, and is partly converted into a basic ferric sulphate.—Dose, 1⁄2 to 4 gr., in pills or solution; externally, as an astringent or styptic. In the arts, as sulphate of iron (copperas), it is extensively used in dyeing, and for various other purposes. The dried sulphate (ferri sulphus exsiccatum) is chiefly used to make pills.
Crude sulphate of iron is frequently contaminated with the sulphates of copper, zinc,
manganese, aluminium, magnesium, and calcium, which, with the exception of the first, are removed with difficulty. It also contains variable proportions of the neutral and basic ferric sulphates. The preparation obtained by direct solution of iron in dilute sulphuric acid should, therefore, be alone used in medicine.
In commerce there are four varieties of crude sulphate of iron or copperas known,—greenish-blue, obtained from acid liquors,—pale green, from neutral liquors,—emerald green, from liquors containing ferric sulphate,—and ochrey brown, which arises from age and exposure of the other varieties to the air. Even the first two of these contain traces of ferric sulphate, and hence give a bluish precipitate with ferrocyanide of potassium; whereas the pure sulphate gives one which is at first nearly white.
Ferrous Sulphide. FeS. Syn. Sulphuret of iron, Sulphide of i., Protosulphide of i.; Ferri sulphuretum (Ph. E. & D.), L. Prep. (Ph. E. & D.) Expose a bar of iron to a full white heat, and instantly apply a solid mass of sulphur to it, observing to let the melted product fall into water; afterwards separate the sulphide from the sulphur, dry, and preserve it in a closed vessel.
From sublimed sulphur, 4 parts; iron filings, 7 parts; mixed together and heated in a common fire till the mixture begins to glow, and then removing the crucible from the heat, and covering it up, until the reaction is at an end, and the whole has become cold.
Hydrated; Ferri protosulphuretum hydratum, L. By adding a solution of ammonium sulphide or of potassium sulphide to a neutral solution of ferrous sulphate made with recently distilled or boiled water; the precipitate is collected on a filter, washed as quickly as possible with recently boiled water, squeezed in a linen cloth, and preserved in the pasty state, under water, as directed under ferric hydrate.
Prop., &c. The sulphide prepared in the dry way is a blackish brittle substance, attracted by the magnet. It is largely used in the laboratory as a source of sulphuretted hydrogen. The hydrated sulphide is a black, insoluble substance, rapidly decomposed by exposure to the air. Proposed by Mialhe as an antidote to the salts of arsenic, antimony, bismuth, lead, mercury, silver, and tin, and to arsenious acid; more especially to white arsenic and corrosive sublimate. A gargle containing a little hydrated sulphide of iron will instantly remove the metallic taste caused by putting a little corrosive sublimate into the mouth. (Mialhe.) On contact with the latter substance it is instantly converted into ferrous chloride and mercurous sulphide, two comparatively inert substances. It is administered in the same way as ferrous hydrate. When taken immediately after the ingestion of corrosive sublimate, it instantly renders it innocuous;
but when the administration is delayed until 15 or 20 minutes after the poison has been swallowed, it is almost useless.