Rubber
The attention of the rubber dealers was at first confined to certain lianas, especially the Landolphia florida, which was regarded as the greatest rubber-yielding plant in the colonies. But in the beginning of the century it was discovered that the great virgin forests of South Cameroon contained vast numbers of Kickxia-elastica trees, and that extensive subsidiary tracts covered with the same plant existed in the savannahs of South Adamana, in the Kumbo highlands, and the region of Lake Chad. Kickxia-elastica, known in the trade as “silk rubber,” was first discovered on the West African Coast in Lagos in 1894, and by October of the following year the exports had reached well over a million pounds. The eagerness of the natives to exploit this very valuable product led to the total destruction of the rubber-yielding trees, with the result that by 1906 the export had entirely ceased. Dr. Schlecter introduced the Kickxia rubber trees from Lagos into the Cameroons, where he proved that 1½ lbs. of dry rubber may be obtained from the six-year-old trees, a result which was more than confirmed subsequently by Dr. O. Warburg, the well-known authority on rubber. The first shipments of rubber from the Kickxia trees were obtained from the wild rubber trees known as Funtumia-elastica, and it has only been during the last few years that the Germans, realising that the Kickxia rubber trees are indigenous to the colony, have cultivated it, and there are now large plantations of Kickxia in the Cameroons containing millions of trees, which are doing well.
From the tapping of wild Funtumia trees, it is known that this species yields latex more readily than others, and that it is almost as sensitive to drastic tapping as Castilloa. Tapping of the cultivated tree has occurred experimentally in Cameroon. These trees, however, do not stand closely-planted, but singly or in rows, and the results must be judged accordingly. It can be assumed that from 3 to 3¾ ozs. are to be expected from six-year-old trees planted at good distances from each other, and 1 to 2 ozs. from closely-planted trees. The method of tapping practised in the last experiments with Funtumia differed from all other methods, in that vertical incisions the whole length of the trunk were made. As to its advantage over the herring-bone system, further observations and a more extended series of comparative tapping trials are first necessary. The rubber is procured by boiling the latex after diluting it with water; treatment with hydrofluoric acid yields a better product. Although Funtumia rubber is at present inferior in quality to that of Hevea and Ficus, and at most is equal to that of the Castilloa, still it may be confidently anticipated that with more suitable preparation it will yield a good serviceable product.