Fig. 20. Cashew-nut, Natural size. The nut of Anacardium occidentale, Linné (Cassuvium pomiferum, Lamarck).
Nat. Ord.—Anacardiaceae, Lindley (Terebinthaceae, Kunth).
COMMON NAME: Cashew-nut.
ILLUSTRATION: Strong's American Flora, p. 125.

Botanical Source and Description.—The cashew-nut is a small tree, native of the East and West Indies and South America. The leaves are alternate, simple, entire, obtuse, and borne on short leaf-stalks. The flowers are very numerous, small, and fragrant; they are produced in terminal, loose panicles. What is known as the "cashew-apple" is the enlarged juicy peduncle which bears the nut. When ripe, it is of a golden-yellow color, obovate in shape, and has a pleasant, acid flavor, but is somewhat astringent. It is much eaten by the natives. The cashew-nut is attached and hangs from the end of the cashew-apple. It is kidney-shaped, and about 1 inch long. It consists of an edible kernel, surrounded by two shells. The outer shell is smooth and of a bright-brown color. Between the two shells there is a very caustic oily substance which produces troublesome sores within the mouths of those who injudiciously attempt to crush the nut between the teeth, in order to obtain the kernel. When fresh, the kernel is pleasant to the taste, and is largely consumed by the natives. Fig. 20 is a drawing, natural size, of cashew-nut in our possession.

Chemical Composition and History.—The cashew-nut was first examined by Cadet, who found in it gallic acid and an acrid resin. Afterward, De Mattos (Jour. de Pharm., 1831), by a more careful investigation, found, in addition, tannin, an extractive substance, a gum-resin, and some green coloring matter. But the most interesting investigation was made by Staedeler, in 1847-1848 (Chem. Gazette, Vol. VI), who examined the viscid liquid contained between the two shells of the nut, having extracted it by means of ether. This liquid is fluid at 15.5° C. (60° F.), congeals at 10° C. (50° F.), is soluble in alcohol and ether, but insoluble in water, and is acrid and caustic; when placed upon the skin, it promptly produces vesication. Staedeler separated this liquid into two constituents, one of which was an oily substance constituting about 10 per cent, fluid at even low temperatures, and forming the vesicating part of the liquid, which he named cardot (C21H30O2). This was associated with an acid substance, white and crystalline, when pure, capable of forming salts with bases, some being crystalline, and others amorphous, and to which Staedeler gave the name anacardic acid. This acid is not vesicating. Cardol was recently investigated by Spiegel and Dobrin (1895), who established therefor the formula C32H50O3.H2O. The tree furnishes a gum in abundance (gomme d'acajou, Fr.), which is brittle, and transparent, resembling gum acacia, with the exception of a slight astringency. which it possesses. When the trunks of the trees are tapped, a milky juice exudes, which is white when fresh, but turns black on exposure, and, in India, is used as varnish. It stains cotton or linen deep-black by exposure to air. The apple yields a liquor by fermentation, called "cashew wine," which is said to be a wholesome drink. The roasted nuts are edible, care being taken, however, that the fumes from the roasting shell do not come into contact with the face, as thereby painful blisters will be produced upon the exposed portions. A tar is said to be prepared from the pericarp which is used in tarring wood-work and boats, to protect them from the ravages of insects, and the gum from the stems is employed by American bookbinders to insure the bindings from destruction by worms and book-pests.

Action, Medical Uses, and Dosage.—The fresh juice of the rind is very acrid and corrosive, producing redness, tumefaction, inflammation, and blisters, on which account it has been employed in the West Indies for the removal of warts, corns, ringworms, and as a stimulant to indolent ulcers. Blisters formed by its application are apt to be very troublesome and annoying. The kernel, especially when roasted, is edible, having a rather sweet and agreeable flavor. Cardol possesses the activity of the juice of the rind, producing vesication, and in the higher animals, when injected hypodermatically, gastric inflammation, with diarrhoea, followed by stupor and paralysis. The bark of the tree was used by Adanson, to cure himself of the peculiar fever of Senegal; it has an agreeable taste, does not appear to affect the nervous system, has a favorable influence upon digestion, and is very effective in its action, having conquered the Senegal fever in cases in which the largest doses of quinine proved unavailable (Comptes Rendus, xxvi, p. 254). Prof. Webster (Dynam. Therap., p. 114) suggests its study in mental disorders, and states that it has been successfully used in the mental weakness, following acute diseases and sexual abuses, in loss of memory, dementia, and in failure of nervous power in the old. From 1/3 to 2/3 of a drop of homoeopathic mother tincture in water, 4 or 5 times a day, is suggested as the proper dose.

Related Species.Anacardium orientale (Semecarpus Anacardium, Linné filius), Oriental cashew-nut, India. The nut has similar properties to the cashew-nut. A brown-black oil having strongly vesicant properties, is derived from the mesocarp of the fruit. Serious eruptions of an eczematous nature follow the vesication produced by it, and bloody alvine discharges and disordered urination have resulted from its application. This nut is the marking-nut of India. It is there used quite extensively in medicine, being prepared for internal use by boiling it with cow-dung and subsequently washing with cold water. The Hindus use it for dyspepsia, neurasthenia, hemorrhoids, and cutaneous diseases (Dymock). The constituents of this nut are probably like those of the cashew-nut, though the brownish oil of the oriental nut differs in giving a green, instead of a red color, in caustic potash solution, and in being precipitated in alcoholic solution, black, instead of red, with basic lead-acetate (Basiner, 1881). The nut is described as black, glossy and smooth, about 1 inch in length, subcordate, obtuse, and flattish.

King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.