Qualities. This root is knotty, externally blackish, internally reddish; Odour, slightly aromatic; Taste, austere and styptic. Chemical Composition. Its active matter is chiefly Tannin, and except galls and catechu, it appears to contain a larger proportion than any other vegetable astringent.[[694]] Solubility. Boiling water extracts all its virtues, as also does spirit. Incompatible Substances. Solutions of Isinglass, the Salts of Iron; Alkalies and Alkaline Earths. Med. Uses. It has been chiefly used in diarrhœa, and it is very efficacious in that which is so frequently attendant on Phthisis. Dr. Fordyce recommends its union with Ipecacuan, by which combination, he observes, we shall astringe the vessels of the intestines, and at the same time relax those of the skin. Forms of Exhibition. In substance, or in decoction made by boiling ℥j of the root in oiss of water until reduced to oj. Dose, of the substance in powder, ʒss to ʒj; of the above decoction f℥j thrice a day. Officinal Prep. Pulv. Cret. Comp. L.
TOXICODENDRI FOLIA. L.E.
(Rhus Toxicodendron.)
Sumach Leaves, or Poison Oak.
Qualities. Its leaves are inodorous, but have a sub-acrid taste. Chemical Composition. Gallic acid, tannin, and a certain acrimonious matter, upon which the virtues of the plant depend, and which, according to Van Mons, is disengaged from the leaves in the state of gas during the night, or while they do not receive the direct rays of the sun. Med. Uses. Dr. Alderson of Hull introduced the leaves of this plant to notice, in whose hands they proved successful in several cases of Paralysis; the same results however have not been obtained by other physicians; the plant has therefore fallen into disuse, and might, in deference to public opinion, be removed from the materia medica. When applied externally it has been known to produce an erysipelatous affection of the skin; a remarkable instance of which lately occurred at the Botanic garden at Chelsea, where a person merely rubbed his eye after having casually touched the plant in question.
TUSSILAGO. (Tussilago Farfara—Folia, Flores.) Coltsfoot.[[695]]
This plant has been regarded as a powerful expectorant from the earliest ages; it is at present only valued for the mucilage which it affords; a handful of the leaves boiled in oij of water, until reduced to oj, will furnish, by the addition of a little sugar candy, a very grateful demulcent.
VALERIANÆ RADIX. L.E.D.
(Valeriana Officinalis. Sylvestris.)
Valerian Root.