Prop. & Comp. Iodide of iron is crystalline; of a green colour, with a tinge of brown; when heated, it gives off violet vapours; very deliquescent; forms at first a greenish solution in water, which rapidly decomposes into free iodine and peroxide of iron: if an iron wire is kept in the solution, the strength remains the same, for, as the iodine becomes free, it dissolves the metallic iron and again forms the iodide. Formula, Fe I + 4 HO. It gives a copious blue precipitate with the ferridcyanide of potassium, and one of similar colour with mucilage of starch, on the addition of a minute quantity of chlorine. It is almost entirely soluble in water, leaving but a very small quantity of red sediment.
Off. Prep. Syrupus Ferri Iodidi. Syrup of Iodide of Iron. (Iodine, two ounces; iron, drawn into wire, one ounce; distilled water, thirteen fluid ounces, or as much as may be necessary; sugar, twenty-eight ounces. Mix the iodine and iron with three ounces of water and heat until the froth becomes white, then filter the liquid while still hot into the syrup which has been previously prepared by dissolving the sugar in ten ounces of water, and mix. The product should weigh two pounds eleven ounces, and should have the sp. gr. 1.385.)
Each fluid drachm of the syrup contains four grains and a-half of iodide of iron. [Made according to the U. S. P., a fluid drachm of the syrup contains about 7 1/4 gr. of iodide of iron.]
Pilula Ferri Iodidi. Pill of Iodide of Iron. (Fine iron wire, forty grains: iodine, eighty grains; refined sugar, in powder, seventy grains; liquorice root, in powder, one hundred and forty grains; distilled water, fifty minims. Agitate the iron with the iodine and water in a strong stoppered ounce phial, until the froth becomes white. Pour the fluid upon the sugar in a mortar, triturate briskly, and gradually add the liquorice.) One grain of iodide of iron is contained in about two grains and a-half of the pill. [In the U. S. P. the liquorice powder is replaced by marsh mallow and gum arabic powder, and the mass divided into pills containing each a grain of the iodide of iron.]
Therapeutics. Iodide of iron possesses the valuable properties of the ferruginous salts, in addition to those of iodine; it is peculiarly applicable to the treatment of scrofulous diseases in cachectic subjects requiring iron; it should be remembered that the proportion of iron to iodide is small, only as 1 to 4 1/2.
Dose. Of iodide of iron, 1 gr. to 5 gr. or more. Of the syrup (containing about 4 1/2 gr. of iodide of iron to 1 fl. drm.), 20 min. to 1 fl. drm. [Of the syrup of the U. S. P., from 15 to 30 minims.] Of the pill, 2 1/2 gr. to 8 gr. or more.