Larch Bark. Larix decidua.
Larch Bark. Laricis Cortex. Br. 1885. Ecorce de Meleze, Fr. Lärchenrinde, G.—The bark of Larix decidua Mill. (Larix europoea DC.) (Fam. Pinaceae) was found by Aldridge to contain gum, starch, resin, and tannic acid of the kind which precipitates the salts of iron olive-green. John Stenhouse has obtained from it a peculiar volatile acid, larixinic acid (larixine). For method of separation, see 16th edition, U. S. D. Larixinic acid occurs in beautiful white, lustrous crystals, often more than an inch long, of a peculiar somewhat empyreumatic odor, and a slightly bitter and astringent taste, inflammable, volatilizing at 93° C. (199.4° F.) and melting at 153° C. (307.4° F.), soluble in 87.88 parts of water at 13.3° C. (56° F.), very soluble in boiling water, soluble in cold but much more so in hot alcohol, and sparingly soluble in ether. It readily crystallizes from its solutions. A very singular and characteristic property is that of forming, when added, in strong solution, in excess, to baryta water, a bulky, transparent, gelatinous precipitate, occupying the whole measure of the liquids if concentrated. The probable formula of the acid is C10H20O5. The inner larch bark possesses astringent and gently stimulant properties, and is supposed to have a special tendency to the mucous membranes. It has been found particularly efficacious in purpura and other hemorrhagic affections, especially hemoptysis, and has been given in bronchitis with copious expectoration, and in diseases of the urinary passages. It has been used also, mixed with soap and glycerin, as a local remedy in psoriasis, chronic eczema, and other cutaneous affections. Of the extract from three to five grains (0.20-0.32 Gm.), of the tincture from thirty minims to a fluidrachm (1.8-3.75 mils) or more may be given every three or four hours.