This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
Origin and Properties. This name has been given to the root, or rather rhizome of Geranium maculatum, a small, herbaceous, perennial plant, growing in woods throughout the United States. It is in pieces from one to three inches long, somewhat flattened, wrinkled, tuberculated, compact, externally brown, internally reddish-gray, inodorous, and of a pure astringent taste, without bitterness, or other disagreeable quality.
Active Principle. This is tannic acid, having the general properties of that principle, but of what precise character is yet undetermined; though if it be true, as stated by some, that the root contains also gallic acid, it must be of the kind found in galls. From a recent analysis of the root by the Messrs. Tilden, who recognized the presence both of tannic and gallic acids, it may be inferred that these are its only active constituents.
Effects and Uses. Cranesbill has the effects on the system of an efficient and pure astringent. From its want of unpleasant taste, it is particularly suited to infants, and persons of delicate palate and stomach. It may be used for all the purposes of the vegetable astringents already detailed, whether external or internal; but has been most highly recommended, as an internal remedy, in chronic diarrhoea and dysentery, and, as a topical application, in cases of aphthous ulceration of the mouth and fauces. It is peculiarly applicable to the looseness of bowels following cholera infantum, in consequence of its exemption from irritant properties.
The dose of the powdered root is from twenty to thirty grains. It is, however, more frequently given in the form of decoction, which may be prepared by boiling an ounce of the bruised root in a pint and a half of water to a pint, and given in the dose of one or two fluidounces, repeated three or four times a day. For infants the decoction in milk, in the proportion of an ounce to a pint, is an eligible preparation, and may be given to a child a year or two old in the dose of one or two fluidrachms, or more largely if required. An extract and tincture have been recommended, but are little used.