108 ECONOMIC CONDITIONS ( No. 98 The best gum , pale in colour and highly viscous, is known locally as ħashab geneina, and is obtained from grey -barked trees, privately owned and grown in a plantation (geneina ). At the beginning of the dry season, usually in December, the collector makes an incision on the under side of the principal branches of each tree of three years or more, and then tears a narrow strip of barkupwardsfor two or three feet. In a few days gum begins to exude, and hardens into pear shaped lumps, which the collector knocks off after about 60 days. The exudation continues till May or June, when the rains begin. The trees remain productive for 15 to 20 years , but are at their best between the ages of 8 and 12 years.

The gum from wild hashabtreesis known as hashab wadi . It exudes naturally, is rather dark in colour, and is of less value than hashab geneina .

An inferior gum, known locally as talh, is obtained from acacias with red and whitebark .

All these gums are soluble in water, can be mixed to form mucilage, and belong to the type known com mercially as gum arabic . Their industrial uses are The finest kindsare used in the clearing of liqueurs, the finishing of silk , and the preparation of water colours ; other good grades are employed in con fectionery and pharmacy, in the preparation of textiles and paper, in calico printing, and in certain dyeing processes ; while the cheaper sorts are used in the manu facture of stationery , matches , and ink .

There arevarious other gum -producing plants in the Sudan, notably Sterculia cinerea, which yields an in soluble, flaky gum similar to tragacanth and known as Tartar gum . Considerable quantities could be collected if a market could be found .

Rubber is collected in considerable quantities from vines (especially Landolphia owariensis) growing wild in the Mongalla, Bahr el-Ghazal, and Kordofan pro vinces. A British company has obtained a lease of the rubber -collecting in the province of Bahr el-Ghazal .

The vines are cut down and dried , and the bark is then numerous .

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