Astragalus gummifer, Labillardiere, or other Asiatic species.
The spontaneously dried gummy exudation from the stems.
Habitat. W. Asia - Asia Minor, Armenia, Kurdistan, Persia, Syria, Greece; mountainous districts.
Syn. Trag., Gum Tragacanth, Goat's Thorn Gum, Doctor's Gum, Hog Gum; Fr. Gomme Adragante; Ger. Traganth.
As-trag'a-lus. L. fr. Gr.
in some species. Gum'mif-er. L. gummi, gum, + ferre, to bear - i. e., plant produces gum. Trag-a-can'tha. L. fr. Gr.
a goat, +
thorn - a goat thorn - i. e., plant thorny like goat's head, ana hedges maae of it resist their onslaughts.
Fig. 196. - Astragalus gummifer (natural size of branch).
Plant. - Shrub .6-1 M. (2-3°) high; stem naked with many straggling, much ramified branches; bark reddish-gray, rough, and marked with leaf-scars, young twigs woolly; leaves 3 Cm. (1 1/5') long, closely placed, pinnate, rachis hard, stiff, persistent for some years as a woody spine, yellow, very sharp-pointed; leaflets 10-15 pairs, 3 Mm. (1/8') long, obovate, grayish-green; flowers small, pale yellow; stamens 10, upper one free, others united in a sheath; fruit small, oblong pod, covered with white hairs; seed 1, reniform, smooth, pale brown. Gum (tragacanth), in flattened, lamellated fragments varying from ribbon-shaped bands to long linear pieces, straight or spirally twisted, .5-2.5 Mm. ( 1/50-1/10') thick, whitish, brownish, translucent, horny; fracture short, easily pulverizable by heat (50° C; 122° F.); inodorous; taste insipid, mucilaginous. Powder, whitish, forming with water a translucent mucilage; microscopically - numerous starch grains, .003-.025 Mm. (1/8325-1/1000') broad, occasional 2-4 compound, many swollen and more or less altered, due to excessive heat used in drying before powdering, by which it loses 15 p. c. Tests: 1. Add 1 Gm. to 50 Ml. (Cc.) of distilled water - swells and forms a smooth, nearly uniform, stiff, opalescent mucilage free from cellular fragments (Indian gum - uneven mucilage with few reddish-brown fragments, separating on stirring in coarse, uneven strings. 2. Shake 2 Gm. with 100 Ml. (Cc.) of water, when fully swollen and free from lumps add 2 Gm. of powdered sodium borate, shake until dissolved - mucilage does not lose transparency, change consistency, or appear slimy or stringy on pouring, even after standing 24 hours (abs. of foreign gums). Solvents: hot water; cold water best. Dose, gr. 5-30 (.3-2 Gm.).
Adulterations. - Cherry Gum (cherry, almond, plum, etc.) - in irregular brownish nodules, insoluble portion not identical with bassorin; Indian (Bassora, Kutera, Hogg) Gum, Persia - broken up in Smyrna and mixed with tragacanth; occurs in yellowish-brown (sometimes whitened with lead carbonate), angular, tasteless masses, swelling with water; Cashew Gum - brownish-yellow, translucent, iridescent, partly soluble in water.
Commercial. - Tragacanth is not a simple plant juice, but a degenerative product due to the transformation of the cell-walls of pith and medullary rays in the stem and older branches, and exudes spontaneously, July-August, through natural, or artificial punctures, longitudinal and transverse incisions (near the base of stem) into the medullary part which alone yields juice; it only flows at night, the shape of opening and rate determining its final congealed outline, the time of hardening for collection (1-2 weeks, dry weather 3-4 days) governing its color - white if congealed rapidly, yellow to brown if slowly, from long exposure to changeable weather; the surface lines indicate the daily concretion while the whiter and more translucent possess greatest value. There are several varieties: 1, Flake (Leaf, Smyrna), usually in broad, thick, yellowish flakes, prominently ridged; the ribbon-like and white flakes are produced in Kurdistan, Persia, often being designated as Syrian; 2, Vermiform (Vermicelli), in very narrow contorted string-like pieces, or confluent coils; 3, Common (Sorts), called in Europe traganton, being the result of spontaneous exudation and incidental collection while gathering higher grades; occurs in tear-like pieces, rounded or irregular, brownish, waxy, and, like the preceding varieties, encloses starch. Enters commerce from ports of Asia Minor (Smyrna, Constantinople), Persian Gulf, Bagdad, etc.
Constituents. - Cellulose, Soluble gum, Bassorin, Polyarabinan-brigatactan-geddic acids, Starch, nitrogenous matter, α-tragacanthan-xylan-bassoric acid, xylan-bassoric acid, bassoric acid, β-tragacanthan-xylan-bassoric acid, ash 3.5 p. c. (more than one-half being calcium carbonate).
Cellulose. - The portion of gum insoluble in boiling water, in cold diluted acids and alkalies; when treated with boiling diluted sulphuric acid yields arabinose, and a cellulosic residue which is soluble in ammonia and bromine.
Soluble Gum. - Not identical with arabin, although its solution is precipitated by alcohol and ammonium oxalate; yields a series of gum acids having the nature of the "geddic acids," but are laevorota-tory, whereas geddic acids are dextrorotatory.
Bassorin. - This is an acid which yields a barium salt and two isomeric acids - α- and β-tragacanthan-xylan-bassoric acid when acted upon by excess of an alkali; the former is soluble in cold water and yields sparingly soluble salts of barium, calcium, and silver; when digested with diluted sulphuric acid yields tragacanthose and xylan-bassoric acid, which when further acted on by 5 p. c. sulphuric acid yields xylan and bassoric acid.
Preparations. - 1. Mucilago Tragacanthae. Mucilage of Traga-canth. (Syn., Mucil. Trag.; Fr. Mucilage de Gomme Adragante; Ger. Traganthschleim.)
Manufacture: 6 p. c. Mix glycerin 18 Gm. with water 75 Ml. (Cc.) in a tared vessel, heat to boiling, remove heat, add tragacanth 6 Gm., macerate 24 hours, stirring occasionally, add water q. s. 100 Gm., beat until uniform consistence, strain forcibly through muslin. Dose, ℥j-2 (30-60 Ml. (Cc.)).
Prep.: 1. Trochisci Sodii Bicarbonatis, q. s.
2. Pilulae Ferri Carbonatis, 1/7 gr. (.01 Gm.). 3. Trochisci Acidi Tannici, 1/3 gr. (.02 Gm.). 4. Trochisci Ammonii Chloridi, 1/3 gr. (.02 Gm.). 5. Trochisci Potassii Chloratis, 1/2 gr. (.03 Gm.).
Unoff. Prep.: Glycerite, 12.5 p. c., + glycerin 77.5, water 18.5.
Properties. - Demulcent, emollient, protective, nutritious.
Uses. - Was not known to the Greeks until 4th-5th century, when its uses were as now - expectorant, for cough, hoarseness, similar to acacia; its superior adhesiveness over the latter renders it a better protective in excoriated surfaces, ulcers, burns, etc. Employed largely for suspending resins, oils, heavy powders, etc., in emulsion. Also to cohere pills (paste: 3j + glycerin ℥j; 4 Gm., + 30 Gm.), troches, etc.; its partial insolubility in the stomach restricts somewhat its popularity.