Ferri Potassio-Tartras. Lond. Potassio-tar-trate of Iron

"Take of sesquioxide of iron, twelve ounces and a half; solution of sesquicarbonate of ammonia, a pint, or a sufficient quantity; bitartrate of potassa, three ounces; hydrochloric acid, half a pint; solution of potassa, four pints and a half or a sufficient quantity; distilled water, three gallons. Mix the sesquioxide with the acid, and digest in a sand bath for three hours: then add two gallons of the water; and after it has stood for an hour, pour off the supernatant fluid. Wash the precipitate, after having added the solution of potassa, with water frequently poured on it; and while it is yet moist, boil it down with the bitartrate of potassa, previously mixed with a gallon of the water If the solution when tested with litmus proves to be acid, drop into it solution of sesquicarbonate of ammonia to saturation. Lastly, filter, and evaporate the solution by a gentle heat, that the salt may be dried."

1 Phillips's Trans- of Pharm. 1837.

2 See Essay on the Iodide of Iron.

Tartras Potassae et Ferri, Edin. Tartrate of Potassa and of Iron.

"Take of purified filings of iron, one part; supertartrate of potassa, powdered, two parts; water, one part Rub them together and expose them to the air in a shallow earthen vessel for fifteen days, stirring the mass daily with a spatula, and keeping it moist by frequent additions of water. Then boil the whole for a short time in four times its weight of water, and pour off the solution from the other faeces. Evaporate the solution to dryness in a water bath, and having rubbed the mass into powder, preserve it in a well-stopped bottle."

Tartarum Ferri, Dub. Tartar of Iron.

"Take of iron wire, one part; thin bitartrate of potassa, in very fine powder, four parts; distilled water, eight parts; or as much as mag be requisite. Let them be put into a flat vessel, and exposed to the air for fifteen days; stirring the mixture, and adding some water daily, so as to keep the iron humid; but not so much as to cover it. Finally, boil it in a sufficient quantity of distilled water, and evaporate the filtered solution to dryness in a water bath. The tartrate of iron must be kept in a well-stopped bottle."

Syn. Tartrate de Fer et de Potasse (F.), Eissenweinstein (G.), Tartrato di Potassa e di Ossido di Ferro (I.).

In the London process, the sesquioxide of iron and the hydrochloric acid are both decomposed, and a sesquichloride of iron and water is produced: the former is decomposed when the solution of potassa is added, and hydrated sesquioxide of iron precipitated whilst chloride of potassium remains in solution. This hydrated oxide thus formed unites with the superabundant acid of the bitartrate of potassa with which it is boiled, and a solution of sesquitartrate of iron and tartrate of potassa obtained: hence the dried mass consists of tartrate of potassa and of iron. In the Dublin process the superabundant acid of the bitartrate of potassa dissolves as much of the oxide of iron as it can take up; and a clear solution is obtained, which by evaporation yields also a true tartrate of potassa and of iron. As it is almost impossible to procure this salt in crystals, the solution may be evaporated to dryness.

Qualities. - Potassio-tartrate of iron is inodorous, has a slightly styptic taste, and is of a brownish-green colour. It is very soluble in water; and deliquesces, in some degree, when exposed to the air, so as to require to be kept in closely stopped phials. The cold solution of the alkalies and their carbonates do not decompose this salt; but it is instantly decomposed when boiled with any one of them, although ammonia and its carbonate in neither state affect it. The strong acids, lime-water, hydrosulphuret of potassa, and infusions of astringent vegetables decompose it, and are, therefore, incompatible in formulae with it. It is composed of 1 eq. of tartrate of potassa = 113.63 + 1 eq. of tartrate of the sesqui-oxide of iron = 106.48, making the equivalent =220.11.

Medical properties and uses. - This salt possesses the same medicinal powers as the other preparations of iron; but from its mildness, slight taste, and ready solubility, it is a more convenient form for the administration of iron to children; and in many cases in which the other saline preparations of it prove nauseating, and sit uneasy on the stomach. It is advantageously given in all the cases in which chalybeates prove useful; and is also extolled as a remedy in dropsy, in which it is supposed to exert both a diuretic and a tonic power. The dose is from grs. x. to 3 ss. given either in a state of solution, or in the form of powder or pill combined with an aromatic or a bitter, such as the extract of gentian.