TRAGACANTH Oil GOAT'S TIIOUN. 



557 



gum wliicli it produces, but also a miicilago 

 obtained from the immature pods. Alpinus and 

 others describe the same plant, and its pro- 

 ducts. 



Although this tree grows abundantly over the 

 vast extent of Africa, yet the gum is procured 

 chiefly from those plants growing near the equa- 

 torial parts of that continent; and it is said that 

 in Lower Egypt, the solar heat is not sufficiently 

 intense for promoting the exudation of the 

 gum. This gum exudes in a liquid state from 

 the bark of the trunk and branches of the tree; 

 and by a short exposure to the sun and air, gra- 

 dually hardens into a solid mass. In Senegal the 

 gum begins to flow when the ti'ee first opens its 

 flowers, and continues during the rainy season 

 till the month of December, when it is collected 

 for the first time. At this period the Moors 

 encamp on the borders of the forest, and the 

 Iiarvest lasts six weeks. The gum, which is in 

 the form of round or oval masses, about the size 

 of a pigeon's egg, is packed in very large sacks 

 of tanned leather, and brought on camels and 

 bullocks to certain ports, where it is sold to the 

 French and English merchants. In the year 

 1787, according to the information of Golberry 

 the annual quantity purchased by the former 

 was about 800,000 pounds; and by the latter 

 400,000. 



In Jackson's account of Morocco, it is stated 

 that from Mogador they export two sorts of gum, 

 one the common gum Arabic, the produce of 

 Morocco, and called Barbary gum; the other 

 finer, called gum Soudan, or Senegal, brought 

 from Timbuctoo by the caravans. It is also there 

 stated, that the gum called Morocco or Barbary 

 gum, is produced from a thorny tree called atalleh, 

 having leaves similar to the juniper. It yields 

 most gum during the parching heat of July and 

 August; and the hotter the weather, and the 

 more sickly the tree appears, the more gum it 

 yields: a wet winter, and a mild summer, being 

 both unfavourable to its production. 



Gum Arabic was originally brought from 

 Arabia by the way of Egypt, to Marseilles; and 

 it was not until the beginning of the seventeenth 

 century, that the Dutch made the gum of Sene- 

 gal known in Europe. 



After the French got possession of that river, 

 they directed their attention to it as an impor- 

 tant object of commerce, and ascertained, by 

 experiments made in the latter half of the seven- 

 teenth century, that gum Senegal was superior 

 to the best gum of Arabia; and for about fifty 

 years it has had the preference. 



M. Adanson examined all the gum trees of 

 West Africa with great care, and has given the 

 best description of them. They amount to forty 

 species; but the three gi-eat forests which supply 

 the Senegal market, consists chiefly of two kinds, 

 one which produces a white gum, called vereck. 



and another called nebuel, which yields a red 

 gum. 



There are two kinds of gum found in the 

 shops, and often sold promiscuously; but distin- 

 guished in commerce by the names of guiu 

 Arabic, and East India gum. 



Gum Arabic is in round tears, transparent, 

 colourless, or of a yellowish hue, of a shining 

 fracture, without smell or taste, and perfectly 

 soluble in water. The pieces which are most 

 transparent, and have least colour, are preferred, 

 and are picked out and sold at a higher price. 

 The East India gum is darker coloured, and not 

 so soluble in water as the other. A gum pro- 

 duced from a species of acacia, in New Holland, 

 is of a still darker colour, and when suspended 

 in water, gives off^ whitish films; and in this and 

 other respects, resembles the gum of the cherry, 

 and other trees produced in this country. The 

 coarsest gum makes the thickest mucilage, 

 according to the experiments of the late Dr 

 Duncan. 



Gum Arabic is a highly nutritious article of 

 food. During the whole time of the gum har- 

 vest in Barbary, the Moors of the desert live 

 almost entirely upon it; and experience has 

 proved that six ounces are sufiicient for the sup- 

 port of a man during twenty-four hours. It is 

 also used for food by the Hottentots of southern 

 Africa; and Dr Sparrman states, that in the 

 absence of other provisions, the Bushmen live 

 on it for days together. 



In medicine, it is employed as a demulcent in 

 coughs and irritable states of the mucous mem- 

 brane, for which it is well adapted, at the same 

 time that it does not, like oily substances, load 

 the stomach. It is also used in combination 

 with other medicines to correct their acrimony, 

 or as a means of suspending them in aqueous 

 mixtures. 



In the arts it is also used, especially in calico 

 printing, to give the proper consistency to the 

 cloth previous to the application of the mor- 

 daunts, and to prevent their running and mixing 

 with each other. An annual consumpt of upwards 

 of 12,000 cwt. of this gum is required in Britain, 

 besides other gums of similar quality. 



Crum Senegal is procured from a species of 

 acacia, a native of Guinea. Its flowers are yel- 

 low, globular, and fragrant. The pods are brown 

 coloured, and rounder, and smaller than those 

 of acacia vera. On incisions being made in the 

 bark of the tree, the gum exudes, but less plen- 

 tifully than the gum Arabic. Gum Senegal 

 resembles gum Arabic in all its qualities, but is 

 rather inferior. 



Tragacanth or Goat's Thorn (astragalus 

 tragacantha ) . Natural family fey2HHe«05(B; dio.- 

 delphia, decandria, of Linnseus. This and some 

 other species, particularly a. vents, yield tho 

 gum tragacanth of commerce. 



