"Take of oak bark, ten drachms; distilled water, two pints, (two pounds and a half Edin.) Boil down to a pint, and strain."

This decoction contains the greater part of the astringent matter of the bark. It is nearly inodorous, has a brown colour and an austere taste; reddens tincture of litmus, and is precipitated by solutions of isinglass, infusion of yellow cinchona bark, the carbonates of the alkalies, the aromatic spirit of ammonia, lime-water, and solutions of sulphate of iron, acetates of lead, bichloride of mercury, and sulphate of zinc, which are, therefore, incompatible in formulae with it. The precipitates produced by the two last salts do not take place for a considerable time. It does not precipitate tartar emetic in solution.

Medical properties and uses. - This is the usual form under which oak bark is exhibited. As a local astringent, it is used as a gargle in cynanche and relaxation of the uvula; as an injection, in passive uterine haemorrhages, epistaxis of aged persons, in leucorrhoea, and the gleety discharge which often remains after miscarriages. It is also an useful wash in piles and procidentia recti.

1 Decoctum pro enemate, P. L. 1787.

2 Decoctum pro fomento. P. L. 1787.