Gum

(gum.) [From A.S. goma, the palate.] (Chem.) A general term applied to certain exudations from trees and plants, which are very different in their chemical characters and their general properties. Gum arabic, which maybe taken as the type of this cla , is an exudation of some species of acacia, and consists e entially of arab ine, which has the composition C12H11011. It di olves readily, even in cold water, forming a viscid liquid, from which the arab ine is precipitated in white flakes on adding alcohol. Gum Tragacanth (C12H10010), which exudes from the Astragalus Tragacanth a, is far le transparent than gum arabic, from which it also differs by not di olving in water, but merely swelling up to a soft gelatinous ma .-(pl.) (Anat.) A fleshy substance, cellular and elastic in texture, enveloping the alveolar sections of the jaws-upper and lower and covering the sockets of the teeth. [s. 430]