Ferri Sulphas Exsiccata. Dried Sulphate of Iron.
Ferri Sulphas Granulata. Granulated Sulphate of Iron. [Not officinal in the U. S. P.]
Prep. Sulphate of Iron is made by dissolving iron wire in sulphuric acid, and crystallizing the solution; the Dried Sulphate of Iron by exposing these crystals to a moderate heat for some time, and finally raising it to 400°, when the water is driven off; and the Granulated Sulphate is made by pouring the hot solution of sulphate of iron into rectified spirit, and stirring the mixture, so that the salt shall separate in minute granular crystals.
Prop. & Comp. Pure sulphate of iron crystallizes in light bluish-green rhomboidal prisms, having an astringent styptic taste; composition (Fe O, So3 + 7 HO); it dissolves in about 1 1/2 times its weight of cold water; is insoluble in alcohol; it generally contains a little persalt; the solution, when exposed, gradually becomes turbid, depositing a reddish-brown sediment of the peroxide; it gives a white precipitate with chloride of barium, and a nearly white one with ferridcyanide of potassium. The crystals should be free from opaque rust-coloured spots, and dissolve in water without leaving any ochry residue. The aqueous solution gives no precipitate with sulphuretted hydrogen. The granulated 7 sulphate occurs in small granular crystals, and has the composition and properties of the ordinary sulphate. Dried sulphate of iron forms a whitish powder, and has the formula, Fe O, So3 + HO, as one equivalent of water is retained at all temperatures below 500° Fah.
Off. Prep. Solution of Sulphate of Iron. Appendix B. (Granulated sulphate of iron, ten grains; boiling distilled water, one ounce.) Used as a test. Sulphate of iron is also used in the preparation of mist. ferri comp.; but in this preparation the carbonate of iron is formed.
Therapeutics. The same as iron salts in general, but in addition it has a powerful astringent action. It may be employed when an astringent is required with iron, as in passive haemorrhages and mucous discharges. It may also be used externally for its constricting powers.
Dose. Of the sulphate or granulated sulphate 2 gr. to 10 gr., in pill or solution recently prepared. Of the dried sulphate from 1 gr. to 5 gr. may be administered. As a medicinal agent, the granulated sulphate has no peculiar advantages, except that it is much less liable to become oxidized than the common sulphate.
Incompatibles. None of the soluble iron preparations should be given with vegetable infusions or tinctures containing tannin or gallic acids, as inky compounds are then formed, which, though efficient as medicines, are not agreeable to the patient.