They are broad, dark green, and lance shaped. The larger vines are often five inches in diameter at the base, with a rough brown bark. The mode of obtaining it is to make an incision in the bark, but not in the wood, and through it the milky sap exudes. A small peg Is then fixed in each hole to prevent its closing, and a cup or calabash secured underneath. When this is full, a number of them are carried to the camp, where the substance is spread in thin coatings upon moulds of clay, and dried layer after layer over a fire. When perfectly dry, the clay mould is broken and the clay extracted from the interior. The _caoutchouc_, though originally white, becomes black from the smoke to which it is exposed while drying. It is in this state brought down to the coast and sold to the traders. "Oh yes," said David. "This is the material with which Mr Mackintosh makes his waterproof coats. He found that it could be re-dissolved in petroleum; and by covering two pieces of woollen or cotton stuff with the liquid, and uniting them by a strong pressure, he formed a material through which no water can penetrate. Some time afterwards, Messrs. Handcock and Broding discovered that, by the addition of a small quantity of sulphur to the _caoutchouc_, it acquired the property of retaining the same consistency in every temperature without losing its elasticity. A further discovery was made by Mr Goodyear, who, by adding about twenty per cent of sulphur, converted it into so hard a substance that all sorts of articles can be manufactured from it for which tortoise-shell had hitherto been chiefly used--indeed, it is difficult to say what cannot be made out of it." Besides india-rubber, the blacks had several huge lumps of ebony and a small number of elephants' tusks, which they had either purchased from other natives further in the interior, or were carrying down to the coast to sell for the original owners on commission. The ebony was brought from the hilly country, where alone the ebony-tree grows. It is one of the finest and most graceful of African trees. The trunk, five or six feet in diameter at the base, rises to the height of fifty or sixty feet, when fine heavy boughs branch forth, with large dark green and long and pointed leaves hanging in clusters. Next to the bark is a white sap wood, and within that the black wood. This does not appear till the tree has reached a growth of two or three feet in diameter, so that young trees are not cut down. The trunk and even the branches of the mature tree become hollow. It generally grows in clumps of three or four together, scattered about the forest.