By HERMAN J. SCHUCHARD, PH.G.
Abstract from a Thesis.
On the hills surrounding San Antonio, Texas, the Algarobia glandulosa, Torrey and Gray (s. Prosopis juliflora, De Cand.), is a thorny shrub, branching directly at or a few feet above the ground; but on rich soil and under favorable conditions it becomes a tree 30 to 40 feet high. The legumes, which are somewhat constricted between the seeds, ripen in July and August, and are then yellowish white, mottled with red, four to six inches long, and contain 10 to 20 seeds. In the unripe state they are bitter, but at maturity have a sweet, pleasant taste, and have been sold by the bushel when grain was scarce in the "Alamo City." The Mexicans and Indians prepare a favorite dish from mezquite beans; after the seeds have been picked out, the pulp is ground into a coarse meal, well seasoned with "chile" (capsicum), wrapped in corn husks and boiled. The roots of the mezquite spread sideways for many yards, but others are said to dip into the ground sometimes 50 feet, thereby enabling the shrub to thrive during the hot and dry season. The wood of the mezquite is very hard, and takes a fine polish, but is usually too crooked and knotted to be used for cabinet work. It is brought to the San Antonio market by the Mexican "carrettas" and sold for fuel, for which it is unsurpassed; it is also used in fencing, and blocks of the wood have been employed to a small extent for paving sidewalks in San Antonio.
During the summer months a gum exudes from the stem and branches, which was brought into notice by Dr. Shumard, U. S. A., in 1854, and described by Prof. Procter (see "Amer. Jour. Phar.," 1855, pp. 14 and 223). The gum dissolves completely in an equal weight of water, in 24 hours, at a temperature of about 70°F., and forms a thick mucilage, of an acid reaction, which is not precipitated by subacetate of lead, or thickened to a jelly by silicates, borates or ferric salts, but which, after acidulation with hydrochloric acid and the addition of alcohol, yields a white precipitate. The gum contains 12.6 per cent. of moisture, and on ignition leaves 2 per cent. of ash; this yields to water 26.229 per cent., containing potassium and a small amount of sodium, while hydrochloric acid dissolves 73.442 per cent., containing mainly calcium (about one-half the weight of ash), with small amounts of magnesium and aluminium. The gum is free from starch, and by boiling with hydrochloric acid is converted into glucose.
Gum mezquite does not appear to be much used at present, as the price of gum arabic is low; it is applicable to all purposes like gum arabic, though the dark-colored varieties may be objectionable in some cases. In medicine it does not only answer as well as gum arabic, but may be used with advantage occasionally, since its solution can be combined with basic lead acetate and with ferric salts without being precipitated. No doubt in time gum mezquite will become a commercial article of some importance. It is generally assorted, according to its color, into four varieties or grades.
NOTE BY THE EDITOR.—The Mexican Pharmacopoeia contains some interesting information on the mezquite, supplementing that given above. The name "mezquite" is applied to Prosopis dulcis, Kunth. P. microphylla, Kunth, and P. juliflora, De Cand.. an extract is prepared from a decoction of the leaves, and this dissolved in water is known under the name of "bálsamo de mezquite," and used in various inflammations of the eye. The fruit is used as food, and by fermentation yields considerable alcohol; the colorless distillate has a peculiar odor, and when of from 50 to 60 per cent. strength is called "Vino de mezquite." The gum is stated to be commonly mixed with another gum, probably obtained from Acacia albicans, which has a much darker color, and the solution of which is darkened by potassa, while the solution of gum mezquite is rendered white by this reagent; the distinction was ascertained by A. Morales in his comparative studies of the Mexican gums.
The American Journal of Pharmacy, Vol. 57, 1885, was edited by John M. Maisch.