c. (Medicinal Hydriodic acid.) Dr Buchanan.—Tartaric acid, 264 gr.; pure iodide of potassium, 330 gr.; dissolve each separately in 11⁄2 fl. oz. of water; mix the solutions, and when the precipitate has settled decant the clear liquid, and add a sufficiency of water to make it up to 61⁄4 fl. oz. The liquid retains a little acid tartrate of potassium in solution, but this does not interfere with its medicinal properties. This preparation “possesses all the therapeutic powers of iodine without its irritating properties.” (Pereira.)—Dose, 1⁄2 to 1 fl. dr., gradually increased to 2 or 3 fl. dr., twice or thrice daily.
Prop., &c. Gaseous hydriodic acid is colourless, fumes in the air, is very soluble in water, and has a density of about 4·4. Liquid hydriodic acid, when strong, is very liable to decompose, and should be kept in well-stoppered bottles. Both the gas and the solution are decomposed by potassium, zinc, iron, and other metals, with the evolution of hydrogen and the formation of salts called iodides.
Iodized Cotton wool. (Mehu.) Prep. Finely powdered iodine (5 to 10 per cent.) is strewn upon loose cotton wool in such a manner that the glass jar in which this operation is performed contains alternate layers of cotton wool and iodine. The mixture is gently heated in the open jar on a water bath to expel the air; when this is accomplished the jar is closed and the application of heat continued for about two hours, during which the iodine vapour thoroughly penetrates the wool, imparting to it a yellow colour.
IODO′FORM. CHI3. Syn. Iodoformum, L. A solid, yellow, crystallisable substance, obtained by the action of iodine on alcohol.
Prep. 1. An alcoholic solution of potash is added to tincture of iodine, carefully avoiding excess; the whole is then gently evaporated to dryness, the residuum is washed with water, and then dissolved in alcohol; the alcoholic solution yields crystals by evaporation.
2. (Paris Pharmaceutical Society.) Pure carbonate of potash, 2 parts; alcohol (84°) 5 parts; distilled water, 15 parts. The potash, water, alcohol, and the iodine reduced to powder are placed together in a flask, and the whole heated in a water bath until the decoloration of the liquid. Another 1⁄2 part of iodine is then added and heat again applied, and the addition of the element is repeated until the liquid remains slightly brown coloured. It is then decolorised by the addition of one or two drops of caustic potash solution, and upon cooling crystals of iodoform are obtained.
These are collected upon a filter, washed lightly with cold distilled water, then dried upon blotting paper and enclosed in well-stoppered bottle.
By the evaporation of the mother liquor iodide of potassium is obtained.
Prop., &c. Nearly insoluble in water; freely soluble in alcohol; the solution is decomposed by caustic potassa into formic acid and iodide of potassa.—Dose, 1⁄2 gr. to 3 gr. Medicinal applications, the same as those of iodine itself.
IPECACUAN′HA. Syn. (Ipecacuanha, L.; Ipecacuhan, E., B. P.) Radix ipecacuanhæ, Ipecacuanha (Ph. L. E. & D.), L. The dried root of Cephaëlis Ipecacuanha, or the true ipecacuanha plant, one of the Cinchonaceæ. “Ashy coloured, tortuous, very much cracked, and marked in rings with deep fissures, having an acrid, aromatic, bitterish taste.” (Ph. L.) It occurs in pieces 3 or 4 inches long, and about the size of a writing quill.—Dose. As an emetic, 10 to 20 gr., assisted by the copious use of warm water; as a nauseant, 1 to 3 gr.; as an expectorant and sudorific, 1⁄2 to 1 gr. It is undoubtedly the safest and most useful medicine of its class. It has recently been highly recommended in dyspepsia, combined with other bitters or aperients. Almond meal is sometimes used as an adulterant in ipecacuanha powder.