Acacia vera. Gum Arabic, Gum Senegal, Egyptian Thorn.
Description: Order and generic characters the same as in Acacia catechu. Mimosa nilotica of Linnaeus. A. VERA: A tree eight to twelve feet high, with a crooked gray stem, and purplish-yellow branches. Leaves alternate, bipinnate, smooth; pinnae two to four pairs; leaflets of the pinnae eight to ten pairs, oblong-linear, a gland between the pinnae, and two opposite white spines at the base of each common petiole. Flowers bright yellow, axillary, petioled, globose, from two to four in a cluster. Calyx bell shaped, five-parted. Legume four or five inches long, nearly flat, smooth, pale brown, contracted deeply at each seed. It is a native of Arabia and Northern Africa, and is valued chiefly for its pure white gum. The species Arabica, Seyal, and Senegal, also yield a similar gum, which is rather inferior in quality.
The gum exudes spontaneously upon the trunk and larger branches, is soft and nearly fluid at first, but hardens by exposure. It begins to flow in December, near the flowering time of the tree and soon after the rainy season. Sickly looking trees yield the most; the natives make incisions in the bark to increase the product; and dry, hot weather favors a heavy crop. It is generally in small lumps, irregularly round, varying in color from a nearly pure white to a light brown. It is moderately hard, rather brittle, presents a smooth fracture, is transparent, and without taste or smell. The best qualities have a very delicate orange tinge. Its powder is a pretty white. It forms a thick and adhesive mucilage with cold or hot water; and the water may be entirely evaporated, leaving the gum behind with its properties unaltered. It is soluble, in connection with sugar, by lime water, and in dilute acids; but not in alcohol, ether, or the oils.
Properties and Uses: This gum is one of the purest of all mucilages; and is nutritive as well as demulcent. It is used to soothe irritation of mucous membranes in dysentery, gastritis, bronchitis, later stages of typhoid, etc. In acute dysentery it relieves the pain by softening and shielding the passages during the discharge of acrid materials; and lessens the mucous discharges by relieving the excitement. It is best employed by dissolving a drachm or more in eight ounces of cold water, and using freely, as the stomach will bear. A dilute preparation will be received for some days, without clogging the stomach. It is merely an adjunct to the other appropriate treatment.
Pharmaceutical Preparations: I. Troches are made by mixing four ounces of gum Arabic, one ounce of starch, and one pound of white sugar, all finely pulverized. Rosewater may then be used to moisten them sufficiently to form into lozenges, and medicines added to suit.
II. A demulcent Mixture is made by steeping and mashing into pulp an ounce of sweet almonds, and adding an ounce of white sugar. These ingredients are then to be triturated with three ounces of water in which an ounce and a half of gum has been dissolved. Then gradually stir in a quart of water and strain. It is a good vehicle for other medicines in any renal or bronchial affection requiring a demulcent.
III. Emulsions are formed by employing this gum as a suspensory vehicle, as directed in the part on Pharmacy. The gum is also used in the manufacture of pills but it renders the article so very hard, that its employment is not advisable.
The Physiomedical Dispensatory, 1869, was written by William Cook, M.D.
It was scanned by Paul Bergner at http://medherb.com
