GULU or Gooloo. HIND. The pod of the mahwa tree, Bassia latifolia. It yields a very useful oil, and is sometimes eaten by the poorer classes.
GUM.
Gomme, PR. Gatah pulut, . . MALAy.
Gorn, DUT. GOMA, SP Gummi, DAN., GER., SW. Pisini, T .....
Gond, . . . eau., HIND. Banka, Jigata, . TEL.
Gomma, . . POET., IT. Zamk, . . . . TURK.
Gums and resins are divisible into gums, gum resins, and resins.
Gums are soluble in water, but not in alcohol.
Gum-resins, being compounds of gum and resins, are partially soluble in water, partly in alcohol ; the gummy matter being separated by one, and the resinous matter by the other.
Resins are soluble in spirits, from which they are in a considerable proportion separated by water. The resins melt on the application of heat, but not so the gums. The chief gum and gum-resin producing plants of Southern Asia are— There are two leading modifications of gum, one of which is repreiented by gum-arabie, and the other by gum-tragacanth. There are many intermediate varieties, amongst which cherry-tree gum may bedistinguishcd ; and the different kinds of gums have been classed under the generic terms of arabine, tragacanthine, and cerasine. ,Gum-arabic, gum of the cherry, gum-tmga canth, and others, flow spontaneously from the branches and trunks of the trees producing them. The gummy matter resides in the bark and albu men ; it is the nutritive juice of the plant. But as the wood absorbs more moisture from the air than the bark, and hence swells more, in C011.90. quence of its enlargement it distends the bark, which by the internal pressure of the wood gives way, and gummy matter escapes.
Artificial Gum.—In the process of calico-printing and for stiffening different goods, an artificially prepared gum has for some years been employed. Starch or feeula is, by the action of diastase—a peculiar azotised substance formed during the germination of seeds—converted into a gummy mucilaginous substance named dextrine. It is also known in commerce under the name of British gum and torrefied starch. The tenn leiocome has been applied by Payen to a modified dextrine, whiter and more soluble than can be obtained by torrefication. It is formed by moistening 1000 parts of dry starch (potato starch is genemlly used) with very dilute nitric acid, consisting of 2 parts of concentrated acid and 300 of water. The
mixture is divided into small blocks, which, when dried in the air, are rubbed down, and exposed in a. proper drying stove to a current of air heated to about 150° or 160°; the powder is aftenvards well dried at a temperature not exceediag 230°. When well made, it dissolves in cold or tepid water as easily as gum-amble.
Gum-Arabic.
Samagb Arabi, . ARAB. Gomma Arabica, . . Ir. Shu-kiau, . . . CHIN. Kapitha, . . . SANSK.
Arabische gom, . Goma Arabigo, . . St% Gomme arabique, . Fu. TAM Arabische gummi, . GElt. Banka , TEL. Gond, . . . . HIND.
Guni-arabie is the produce of species of Acacia growing in Arabia, India, Upper Egypt, Senegal, etc. Acacia seyal, A. Ehrenbergii, A. tortilis, A. vera of Africa, all yield the gum-arabic of com merce. That known in commerce a-s the finer gum Senegal is said to be the produce of A. vera. A. albida (the A. Senegal of Willde.), A. seyal, and A. Arabic°, also yield it, and the inferior reddish varieties from A. Adanonii. Barberry gum is said to be the produce of A. gummifera. - Gum Senegal is exported from Portendic, Sierra Leone, and the Frendi settlements on the Senegal, being produced chiefly in the desert country to the north of the Senegal. A. vera is stated by the authors of the Fl. de Senegambie to yield the pale and fine varieties, A. albida (A. Senegal, Wale.) and A. Adansonii the inferior reddish varieties. A. Seyal, A. vera, and A. Arabica are found in Senegambia.
Barbary Gum is exported from Mogador on the west coast of Africa. It is of inferior quality, and, moreover, a mixture of two or three kinds.
The East India Gum of commerce is the produce of A. Arabica, A. serissa, "Egle marmelos, Feronia clephantum, Azadirachta Indica, Melia azeda rad, Odina wodier, and Prosopis spicigera. It is known as Gond, Babul gond, aud Ghatti gond. It occurs in rounded pieces or tears, and in frag ments, up to the size of a wahmt or larger. It dissolves almost completely in water. The solu tion is purer when made with cold water, and keeps better.