Pur. Medicinal ferric oxide or sesquioxide of iron (FERRI SESQUIOXYDUM, Ph. L. & D.) is soluble in dilute hydrochloric acid, scarcely effervescing, and is again thrown down by potassa. The strained liquor is free from colour, and is not discoloured by the addition of either sulphuretted hydrogen or ferrocyanide of potassium.
The hydrate (FERRI PEROXYDUM HYDRATUM—Ph. D., FERRUGO—Ph. E.) is entirely and very easily soluble in hydrochloric acid, without effervescence; if previously dried at 180° Fahr., a stronger heat drives off about 18% of water.
Uses, &c. The precipitated oxide is employed in medicine as a tonic and emmenagogue, in doses of 10 to 30 gr.; and as an anthelmintic and in tic douloureux, in doses of 1 to 4 dr., mixed up with honey. It is also
employed to make some preparations of iron. The calcined oxide is employed as a pigment, as an ingredient in a plaster, &c. The hydrate is used medicinally as a tonic in doses of 10 to 30 gr.; and in much larger, as an antidote in cases of arsenical poisoning.
We are indebted to Bunsen and Berthold for the introduction of this substance as an antidote to arsenic. A table-spoonful of the moist oxide may be given every 5 or 10 minutes, or as often as the patient can swallow it. (Pereira.) When this preparation cannot be obtained, rust of iron or even the dry so-called carbonate (sesquioxide) may be given along with water instead. According to Dr Maclagan, 12 parts, and to Devergie, 32 parts, of the hydrate are required to neutralise 1 part of arsenious acid. Fehling says that the value of this substance as an antidote to arsenic is materially impaired by age, even when kept in the moist state. The presence of potassium, sodium, ammonium, hydrates, sulphates, chlorides or carbonates, is not of consequence, and, therefore, in cases of emergency, time need not be lost in washing the precipitate, which, in such cases, need only be drained and squeezed in a calico filter. The magma obtained by precipitating ferrous sulphate with magnesia, in excess, and which contains free magnesia and magnesium sulphate, besides ferric hydrate, precipitates arsenious acid not only more quickly, but in larger quantity, than ferric hydrate does when alone. It will even render inert Fowler’s solution, and precipitate both the copper and arsenic from solutions of Schweinfurt green in vinegar, which the pure gelatinous oxide alone will not do.
Soluble Saccharated Oxide of Iron. (G.) Syn. Ferrum oxydatum saccharatum solubile. Prep. Solution or perchloride of iron (sp. gr. 1·480), 2 oz. (by weight); syrup, 2 oz. (by weight); mix, and add gradually, solution of caustic soda (sp. gr. 1·330); 4 oz. (by weight); and set aside for 24 hours; then add to the clear liquid 30 fl. oz. of distilled hot water; agitate and set aside. Pour off the supernatant liquid from the precipitate which will have formed, and pour on fresh distilled water; then collect the precipitate on a filter and wash thoroughly with distilled water.
Put the drained precipitate into a porcelain vessel, and mix with it 9 oz. of sugar in powder, and evaporate to dryness with constant stirring over a water bath, then mix in enough sugar in powder to make up 10 oz. by weight; reduce to powder and keep in a closed vessel. One hundred parts contain three of metallic iron.
Ferric Nitrate. Fe2(NO3)6. Syn. Proto nitrate of iron, Nitrate of sesquioxide of iron; Ferri pernitras, L. By digesting nitric acid (diluted with about half its weight of water) on iron or ferric hydrate. A deep-red liquid, apt to deposit a basic salt. It is used in dyeing, and has been recommended in
dyspepsia, calculous affections, and chronic diarrhœa.—Dose, 5 to 10 or 12 drops.
Ferric Phosphate. Fe2H3(PO4)3. Syn. Ferric orthophosphate (Odling); Ferri sesquiphosphas, Phosphas ferricus, L. A white powder obtained by precipitating ferric chloride by sodium phosphate.—Uses and dose. As the last.