Medicinal properties and uses.-Catechu is one of the most valuable of the vegetable astringents; and as the dark-coloured contains the greater quantity of tannin (tannic acid), on which its astringency depends, it is to be preferred for medicinal use. It is employed with the best effects in dysentery and diarrhoea, when the use of astringents is admissible; in alvine and uterine haemorrhages, leucorrhoea, gleet, and in obstinate catarrhal affections. As a local astringent, it is used in sponginess of the gums, and aphthous ulcerations of the mouth and fauces; and 1 have found the slow solution of a small piece of it in the mouth, a certain remedy for the troublesome cough induced by a relaxed uvula hanging into and irritating the glottis; and on the same principle it is used by public singers to prevent hoarseness. Dr. Paris 3 recommends it as a dentifrice, especially when the gums are spongy; and I can verify this recommendation when the Catechu is combined with three parts of finely-powdered charcoal.

In prescribing it, the practitioner should bear in mind, that alkalies and their carbonates destroy its astringency; that the morphia in laudanum and in wine of opium is thrown down by it; that the active principle of Ipecacuanha is destroyed by it; that metallic salts, with the exception of protosulphate of iron, form with it insoluble compounds; that it is precipitated by lime and baryta water, alum, nitrate of potassa, ferrocyanate of potassa, and sulphate of magnesia; and that isinglass and albumen also precipitate it where alkalies are not present.

1 Tincture of muriate of iron produces a precipitate, which, on the addition of Liq. Potassae, is redissolved, unless the quantity of the tincture be great, and the solution becomes of a deep purple or port wine colour.

2 Philosophical Transactions, 1803.

3 Pharmacologia, 3d edit.

An ointment composed of iv of Catechu, 3 ix of Alum,

iv of white Resin, and f ; x of Olive oil, with a sufficient quantity of water, is in great repute in India as an application to ulcers.

The dose of Catechu may be from grs. x. to 3 j.

Officinal preparations. Infusum Catechu composition. L. D. Infu-sum Acacia Catechu. E. Tinctura Catechu. L. E. Electuarium Catechu compositum. E. D.

2. Acacia vera.1 Officinal. Acacia, Lond. Acaciae Arabicae Gummi, Edin.