How to use Gum-arabic in a sentence
The majority of plant specimens are most suitably fastened on paper by a mixture of equal parts of gum tragacanth and gum arabic made into a thick paste with water.
Omdurman is the headquarters of the native traders in the Anglo-Egyptian Sudan, the chief articles of commerce being ivory, ostrich feathers and gum arabic from Darfur and Kordofan.
When these fires occur while the trees are full of sap, a curious mucilaginous matter is exuded from the half-burnt stems; when dry it is of pale reddish colour, like some of the coarser kinds of gum-arabic, and is soluble in water, the solution resembling gumwater, in place of which it is sometimes used; considerable quantities are collected and sold as " Orenburg gum "; in Siberia and Russia it is occasionally employed as a semi-medicinal food, being esteemed an antiscorbutic. For burning in close stoves and furnaces, larch makes tolerably good fuel, its value being estimated by Hartig as only one-fifth less than that of beech; the charcoal is compact, and is in demand for iron-smelting and other metallurgic uses in some parts of Europe.
At one time also some species were used in the arts for supplying a gum as a substitute for gum-arabic. These were chiefly Ramalina fraxinea, Evernia prunastri and Parmelia physodes, all of which contain a considerable proportion of gummy matter (of a much inferior quality, however, to gum-arabic), and were employed in the process of calico-printing and in the making of parchment and cardboard.
A kind of thick paste, known as jujube paste, was also made of a composition of gum arabic and sugar dissolved in a decoction of jujube fruit evaporated to the proper consistency.Advertisement
The fruits of Zizyphus do not enter into the composition of the lozenges now known as jujubes which are usually made of gum-arabic, gelatin, &c., and variously flavoured.
True gum-arabic is the product of Acacia Senegal, abundant in both east and west tropical Africa.
Acacia arabica is the gum-arabic tree of India, but yields a gum inferior to the true gum-arabic. An astringent medicine, called catechu or cutch, is procured from several species, but more especially from Acacia catechu, by boiling down the wood and evaporating the solution so as to get an extract.
Mixed with gum arabic it forms a marking ink for linen.
Characteristic of the Sahara is the date-palm, which flourishes where other vegetation can scarcely maintain existence, while in the semi-desert regions the acacia (whence is obtained gum-arabic) is abundant.Advertisement
The acacia tree is common, and from it gum-arabic of good quality is obtained.
His early work on the movements of gases led him to examine the spontaneous movements of liquids, and as a result of the experiments he divided bodies into two classes - crystalloids, such as common salt, and colloids, of which gum-arabic is a type - the former having high and the latter low diffusibility.
Gum senegal, a variety of gum arabic produced by Acacia Verek, occurs in pieces generally rounded, of the size of a pigeon's egg, and of a reddish or yellow colour, and specific gravity 1.436.
Process 1. Dissolve gum arabic in water and mix it with a pigment and a solution of potassium bichromate or ammonium bichromate.