Ferrous Citrate. Fe3(C6H5O7)2. Syn. Protocitrate of iron, Citrate of protoxide of iron. This salt is easily formed by digesting iron filings or wire with citric acid, and evaporating the solution as quickly as possible out of contact with the air. It presents the appearance of a white powder, nearly insoluble in water, and rapidly passing to a higher state of oxidation by exposure to the air. Its taste is very metallic. It is exhibited under the form of pills, mixed with gum or syrup, to prevent it from being prematurely decomposed.
Ferrous Ferricy′anide. Syn. Ferridcyanide of iron. Prep. By adding a solution of potassium ferricyanide (‘red prussiate of potash’) to a solution of ferrous sulphate (or any other soluble ferrous salt), and collecting and drying and precipitate. A bright-blue powder. (See Turnbull’s blue.)
Ferrous Hydrate. Fe2(HO)2. See under Ferrous oxide.
Ferrous Hydrate. Fe(HO)2. May be precipitated from ferrous solutions as a white powder, by alkaline hydrates. It rapidly absorbs oxygen, and turns first green, and
then red, by exposure to the air. Both the oxide and hydrate are very powerful bases, neutralising the acids and forming stable salts, which, when soluble, have commonly a pale green colour, and a nauseous metallic taste.
Ferrous Hypophosphite. Syn. Ferri hypophosphis. From the double decomposition of hypophosphite of lime and sulphate of iron, as hypophosphite of potash.
Ferrous Iodide. FeI2. Syn. Protoiodide of iron, Iodide of iron; F. iodidum, Ferri hydriodas, F. ioduretum, L. Prep. (B. P.) Fine iron wire, 1; iodine, 2; distilled water, 10. Introduce the iron, iodine, and 8 of water into a flask, heat it about ten minutes, and boil until all the red colour is gone. Filter through paper into a polished iron dish, washing with the rest of the water, and boil until a drop of the solution taken out on iron wire solidifies on cooling. Pour on porcelain and cool. (Ph. L. 1836.) Iodine, 6 oz.; iron filings, 2 oz.; water, 41⁄2 pints; mix, boil in a sand bath until the liquid turns to a pale green, filter, wash the residuum with a little water, evaporate the mixed liquors in an iron vessel at 212° Fahr. to dryness, and immediately put the iodide into well-stoppered bottles.
Iodine, 1 oz., and clean iron filings or turnings, 1⁄2 oz., are put into a Florence flask with distilled water, 4 fl. oz., and having applied a gentle heat for 10 minutes, the liquid is boiled until it loses its red colour; it is then at once filtered into a second flask, the filter washed with water, 1 fl. oz., and the mixed liquid is boiled down, until it solidifies on cooling.
With sugar: Saccharine iodide of iron, Saccharum ferri iodidi, Ferri iodidum saccharatum, L. Iron (in powder), 1 dr.; water, 5 dr.; iodine, 4 dr.; obtain a solution of iodide of iron, as above, and add to it of sugar of milk (in powder), 11⁄4 oz.; evaporate at a temperature not exceeding 122° Fahr., until the mass has a tenacious consistence, then further add of sugar of milk, 1 oz., reduce the mixture to powder, and preserve it in a well-stoppered bottle. Every 6 gr. contains 1 gr. of iodide of iron.
From “syrup of iodide of iron” exposed in a shallow vessel, in a warm place, until it crystallises; the crystals are collected, dried, and powdered. A simpler plan is to gently evaporate the whole to dryness, and to powder the residuum. The saccharine iodide may be kept for some time in a corked bottle without undergoing decomposition.