This is among the most valuable of the chalybeates. It is prepared, according to the method of Soubeiran, which has been adopted in the U. S. and Br. Pharmacopoeias, by adding gradually to a heated mixture of bitartrate of potassa and water, the recently precipitated hydrated sesquioxide of iron (see page 443), constantly stirring, until the latter ceases to be dissolved; then filtering, evaporating to the consistence of syrup, and drying in thin layers.

Composition

It is probable that, in the above process, half of the tartaric acid leaves the bitartrate of potassa, and combines with the ses-quioxide. According to Soubeiran and Capitaine, the salt contains 30.49 per cent. of the sesquioxide. It may be supposed to consist of one equivalent of tartrate of potassa, and one of basic tartrate of sesquioxide of iron (one eq. of acid and one of base F203), chemically combined; the latter ingredient probably acting the part of an acid in the compound. Butother views have been taken of its chemical nature; and its insensibility to certain reagents which ordinarily act strongly on iron in its soluble forms, would seem to show that its metallic constituent is in a peculiar state of combination.

Properties

As above prepared, the salt is in translucent scales, of a ruby-red colour, and permanent in the air; but, as formerly made, and still frequently found in the shops, it is in the state of a dark-greenish or olive-coloured powder, slightly deliquescent on exposure. The preparation is inodorous, of a mild, sweetish, slightly chalybeate, and not disagreeable taste, freely and wholly soluble in water, slightly so in alcohol, and considerably in diluted alcohol or wine. Its watery solution is not rendered blue by ferrocyanide of potassium, nor precipitated by the alkalies at ordinary temperatures, nor sensibly affected by the ordinary acids. Astringent vegetable infusions, however, affect it in the same manner as other ferruginous solutions.

Medical Use

In one or another form, this chalybeate has long been in use; but is not at present, I think, employed as much as it deserves to be. With little disposition, notwithstanding its solubility, to irritate the stomach, and almost destitute of astringency, it is yet capable of readily imparting its iron to the system, and produces all those effects upon the blood and the tissues which characterize the ferruginous preparations. Without, therefore, being a very efficient remedy in dyspepsia, diarrhoea, or hemorrhages from the primae viae, in which it is inferior to other soluble salts, it may be employed with advantage whenever the object is to improve the blood, or produce a tonic impression directly on the system. With a view to these results, and without reference to a specific or peculiar influence of any kind, I should prefer it to all other soluble chalybeates. It may require to be exhibited in a larger dose than they; but, even in equivalent quantities, in relation to the iron it gives to the blood, it is less irritant to the stomach. Another advantage is its less tendency to constipate. Its want of unpleasant taste, as well as its general mildness, admirably adapt it to the cases of young children; and it is wonderful how soon it will restore a healthy colour to their cheeks, in the lowest states of anaemia, when purely functional. The dose for an adult is from ten to thirty grains, three or four times a day, to be given in solution. Three or four grains of it may be given to a child from two to four years old.

Wine of Iron (Vinum Ferri, Br.), which is a vinous solution of this salt, has been long in use as a chalybeate. The British Pharmacopoeia prepares it by simply dissolving the tartrate of iron and potassa in sherry wine. Formerly the London College directed it to be made by digesting iron wire in sherry wine for a month. The iron was oxidized at the expense of the air or water, and then combined with the excess of tartaric acid of the bitartrate of potassa always present in wine, forming a salt which was probably essentially the same, so far at least as medical effect is concerned, with the one above described. The present plan, therefore, while yielding an equally efficient preparation, is preferable in point of precision; as, by the old method, the strength of the preparation depended on the character of the wine. The preparation is a weak chalybeate, adapted to cases requiring the use of iron, and in which the patient has been in the habit of using wine regularly. It has the advantage over an aqueous solution, of not being liable to the spontaneous decomposition of the organic acid. The dose is from half a fluidounce to two fluidounces, two or three times a day.