GUMS. A class of organic substances mostly of vegetable origin, and composed of carbon, hydrogen, and oxygen. Many of them are com pletely soluble in water, forming with it a trans parent mucilage; but they are all insoluble in alcohol. Chemically, the gums are amorphous carbohydrates that are transformed into sugar when heated with dilute acids. The finer varie ties are used pharmaceutically for making emul sions and emollients. Other gums are used in the manufacture of confectionery, in calico-print ing, in making ink, finishing cloth, etc. With reference to their chief constituents, the gums may be subdivided into the following three groups: (1) Gum arabic and similar gums, con taining °rabbi; (2) gum tragacanth and similar gums, containing bassorin;• (3) other gums, con taining cerasin, such as cherry-gum, peach-gum. etc.
Gum arabic, or gum acacia, is gathered chiefly from the Acacia Senegal, growing in Eastern ' Africa, and near the Senegal River in Western Africa. It is brought into the market in the form of roundish tears, varying in color from a light straw to a garnet red, and is more or less transparent; the lightest is always the best. Picked Turkey gum is the most esteemed variety. Gum arabic consists chiefly of ambit) (arable acid), combined with calcium. magnesium. and potassium. Barbary or Morocco gum. a dark colored variety, has some qualities which render it valuable to confectioners. Gum Gedda is an inferior quality, now but seldom met with in commerce. Gum. Senegal comes in line, large. round tears, generally larger and of a darker color than the finest gum arable. It is found in tropical parts of the western coast of Africa. Hum gattic, an Indian gum, is used as a substitute for gum amide. Other varieties are: Cape gum, the Australian wattle gum, etc. Wood-apple f/11114 is often used as an adulterant of gum ara bic. The East Indian gums are dark colored, and much inferior to those produced in Africa.
(2) Gum Tragacanth. or gum dragon (Fr. gomme adragantc; Ger. Traganth), is a gummy exudation from various species of Astragalus ( natural order Legmininosfr). It is derived chiefly from the Astragalus growing in West ern Asia, and comes into the market by way of Smyrna and Constantinop'e. The best Sort is the flaky tragacanth of commerce; vermicelli and common tragacanth are cheaper varieties. Traga canth is dull, translucent, horn-like, and has a white or yellowish color. It contains both arabin and bassorin; when the gum is treated with water, the portion containing arabin goes into solution, forming a mucilaginous liquid, while the bassorin remains undissolved. Tragacanth has a soothing action when applied to a sore throat. It also finds considerable application in the arts, being much valued as a stiffening ma terial for various textile fabrics. The following gums are more or less closely allied to gum tragacanth: Bassora gum, which is used to adul terate tragacanth; wood gum, which is derived from the birch, ash, oak, willow, etc.
(3) Cherry-tree gum is a colorless or yellow gum used for stiffening hats. It swells with water, forming a slimy paste. In contains a con siderable amount of the insoluble substance cerasin.
Sugar-beet gum, Irish-moss gum, and a few other gums contain substances which differ some what in their properties and reactions from the arabin, bassorin, and cerasin mentioned above. Sugar-beet gum contains pararabin; Irish-moss gum contains lichenin.
A substance named animal gum has been ex tracted from the salivary and mucous glands. It is a carbohydrate closely resembling the vege table gums; soluble in water, insoluble in alcohol. Like the vegetable gums, it is transformed into sugar when boiled with dilute acids.