Gum Tragacanth

Tragacanth is a gum obtained by the exudation from the stem of Astragalus gummifer, and other species of Astragalus, small shrubs widely distributed throughout the Turkish Emire and Persia. It appears to be produced by the process known as gummosis of the cell walls in the pith and medullary rays. It swells by absorbing water and on account of the pressure in the interior of the stem finally forces itself out through cracks or through artificial incisions which are made to increase the flow. It is collected when dry and graded for market. The finest gum which has been exuded from the long incisions dries almost white in colour and in flakes and is known as “flake” Tragacanth, being graded according to appearance. The portions which are forced through more or less rounded holes, and which dry in tears or vermiform pieces, are known as “vermicelli” tragacanth. The more inferior qualities are known as “hog” tragacanth. Two varieties of “flake” tragacanth are found on the London market viz., the Persian and Smyrna varieties. Persian tragacanth occurs in thin, horny, translucent flakes. The Smyrna variety is more opaque and less ribbon-like. “Hog” tragacanth appears to be little good and is the caramania gum. It occurs in yellowish or brown opaque pieces, and it resembles the genuine tragacanth in most respects.