GUM-RESINS, which are much more mixed in their chemical constituents; in general terms, however, they may be said to consist of certain resins soluble in alcohol, and of the true gum, so that it requires both water and alcohol to dissolve them entirely. They are chiefly used in medicine and perfumery, and may be said to form a connecting-link between the true gums and the true resins, commercially speaking. The principal are: 1. Gum asafedida. See ASAFOETIDA. 2. Glint bemoan or benjamin. Sec BENzoiN. 3. Guns styrax or sturaz is another sweet-scented gum-resin, produced by styra.c (Skin ails in Turkey in Asia. It is usually liquid, of the consistence of treacle, and a blackish or dark-gray color. It is also used in perfumery. 4. Guns sagapenum, another medicinal is with unpleasant garlic-like odor, dark-brown color, and a soft consist ency. It s not known what plant produces it, but it is generally supposed to be obtained from a fe•uk. 5. Guns galbattum. See GALBANUM. 6. Gum opopana.c is yielded by the roots of another unbelliferous plant, opopanax ebironium. It conies from the Levaut in reddish-yellow lumps of a disagreeable smell. Its only use is in medicine. chiefly for plasters. 7. Gum ammoniacum. See AMMONIACUM. 8. Gum myrrh is a very sweet-smelling gum resin, which exudes from the stems of an Abyssinian shrub, the balsomodendron myrrha. Two distinct kinds are known in commerce, the Turkish and the East Indian; the former is the better. They are both in irregular-shaped small
lumps, rarely exceeding the size of a walnut, of a reddish-brown color, rather lighter in the Turkish sort. Considerable quantities are used in medicine, and in perfumery for dentrifices, washes for the teeth, etc., in consequence of its being supposed to possess considerable antiseptic properties, and for the agreeable odor it imparts to the breath. From 15 to 20 tons are imported annually. 0. Gum is obtained from incisions made purposely in the crown of the great tap-root of the conroIrtelmt seammonia, which is bored for the purpose. It is of a dark sap-green color, inclining to greenish gray, in large and small cakes, and in irregular fragments. Its use is extensive as a mild and safe purgative for children, but scarcely any has been so uncertain in its operation, owing to the excessive adulteration practiced upon it by the Turks previous to its shipment. This has now been obviated by importing the root itself, and extract ing the guns in this country.
There are many other gums known, but these are the ones to be had in shops. and for which uses are found iu the tarts, manufactures, and iu medicine. Many also of the true resins, as copal animi, etc., are called gums, but they are strictly resins. See