AFRIQAN —Much ignorance still prevails conceraing the sources aad collection of the .A.frican rubbers. The 1V1ozambique and lVladagascar kinds are obtained from the clinabing shrubs ved-here or voa-canja (Vahea madagascariensis), vod-hini (V. comorensis), and V. gummifera. The product of one of tlaese species is said to be much superior to the others, but all are mixed indiscriminately by the natives. The preparation consists in treatment either with salt water or artificial heat. The Mozambique article occurs in orange-like balls ; in " sausages," formed of slender strings of rubber wound upon a stick, which is finally withdravvn ; and occasionally in smooth pieces of vririous size, termed "cake " or " line." The Madagascar sort consists of shapeless lumps, the better quality having a pink colour, and the lower a black, Some rubber is produced in Mauritius by Cryptostegia grandiflora, and some by Widtsjhbeia edulis, the latter found also in Madagascar, Chittagong, and Silhet.
A belt ef rubber-yielding plants of different species extends across Tropical Africa from ocean to ocean. Within 20 miles of the coast from Liawa and the Lindi estuary (Mascsi and Rovuma, E. Africa, 11° S , 38° E.), the forest becomes almost entirely formed of indierubher vines, affording all abundant supply of fine rubber, at present gathered only in a very desultory manner by the natives, who gash tLe plants, end collect the exuding juice, which issues in a liquid form, aud dries hard after short exposure to the air. Rolled into orange-like balls, it is taken to Lindi, where it is purchased by the Banyan mi rehants at about a quarter its value. Dr. Kirk has determined the plant which yields the beet E. African rubber, and has obtained seeds of the species for intro duction into India. It occurs in great abundance aloug the newly-made road from Dar-es-Salaam, in a W.-S.-W. direction, for about 100 milee towards the interior of E. Africa, through the Wazamaro country ; it is apparently but little affected, except in the immediate neighbourhood of the villages, by the reckless mode of tapping employed. In mauy parts, a native can still eollect 3 lb. of rubber daily. There are five species, but only one is considered worth tapping. Specimens received from him at Kew have been named Landolphia florida and L. Kirkii, the latter of which yields the best rubber. The Lande/phia vine is knowu from Pangani inland all the way to Handel (in Usambara, E. Africa); at Magila, the rubber is made into balls for export. Dr. Kirk states that L. o,ariensis is common along the matitime region of E. Africa, and abundant at the mouth of the Zambesi, beiug fouud largely at Shupanga en that river at 100 miles front the coast. The produce of this has been shipped from Quillimane fur America. The natives of the Marutse Mabuntla empire, on the Upper Zambesi, trade in rubber with the tribes to tho west. The district called Mungao, extending from S. lat. 9° 25' tu Delgado in 10° 41', yielded 90,0001. worth of rubber in 1877, when the industry had been only 3 years in existence. In 1878, Kilwa and Mombasa added largely to the supply. Ou the Victoria Lake, arc one er two kinds of tree producing rubber of good quality. Rubber plants grow on the slopes of the Cameroons mountains (W. Africa), but the people do not yet knuw their value. Rubber trees abound on the rivet Djour, in the province of Bahr el Ghazal.
The Landolphia spp. are principal among the rubber plants of W. Africa. The rubber is col lected from L. owuriensis, extendiug from 10° N. to 10° S. on the coast of IV. Africa, and most abundant in tho highland districts of Angola ; L. florida, frequent in inuer Angola up to 1500— 2500 ft., and in Liberia; ancl L. Heudelotii in Senegal. Accordiug to Speke aud Grant, the natives say that the best rubber is produced by L. florida. The plants of this genus nre woody climbers, growing well in damp rocky raviues scarcely available for other culture. Being climbers, they could not be grown in separate plantations, but would probably flourish in any tropical jungle, where trees already existed for them to ascend. Every part of the stem exudes a milky juice when cut or wounded, but this will not run into a vessel placed to catch it, us it dries so quickly as to form a ridge on the wound, wbich stops its further flow. The blacks collect it by rnaking long
cuts in the bark with a kuife, and as the milky juice gushes out, it is wiped off continually with the fingers, and smeared on their arms, shoulders, and breast, till a thick covet tug is formed. This is peeled off their bodies, and cut into srnall squares, which are then said to be boiled in water. According to other accouuts, the natives cut off a pie,ce of the bark, and the milky juice is allowed to run into holee in the ground, or upon leaves. In some districts, they simply let the juice trickle down their arms, going from tree to tree till sufficient has accumulated, then peeling it off from the elbow in the form of a tube. Elsewhere, it is said to be collected and left to inspissate in wooden vessels. Collins remarks that, if the incisions be allowed to penetrate too deeply, they liberate a gummy substance, which, mingling with the rubber, depreciates its value. These vines may be tapped fur rubber when 3 years old. Christy suggests their cultivation in plantations, and annually cutting down tbe young shoots almost to the ground, then crushing the stems between rollers, and treating the whole mass with carbon bisulphide, which dissolves the rubber, but not (he says) the injurious gummy matter. The rubber of these vines is of fairly good quality when carefully prepared. It should be made in separate sheets or cakes, 1-2 in. thick and 6 in. or so in diameter. Iron or stone vessels are superior to clay for collecting the juice. The better kinds are said to be prepared with the addition of 3 per cent. of strong liquor ammonia3. When any liquid is added in the preparation, the sheets must be very thin, to facilitate drying. This question of drying seems to have much to do with the quality of the rubber, and the inferiority of African to Para rubber is largely attributed to its being sent iuto commerce in a raw, green state, whence possibly also arises its disagreeable odour, geuerated by decomposition. The desirability of intro duc.ing the Attalea excelsa, for the purpose of employing its nut (the urueuri) in curing African rubber, ss in Pam (see p. 1661), has even been discussed ; but the slow smoky fire from any oily nut would probably have the same effect.
Another important W. African plant is Urostigma Vogelii, with possibly some other species. The tree (20-30 ft.) grows near the sea, at elevations of 50-60 ft., but does not flourish in marshy ground. The natives pollard the trees at 10-12 ft., and cut back the branches, thus obtaining a free and regular flow of sap. The cuttings are easily propagated, and grow vigorously. The trees are tapped at about 5 years, by making slashes or incisions in the trunk ; the juice is collected in vessels, inspissated by the use of acids, and made up iuto balls the size of a large orange. Though often sent in a dirty state, the rubber is of good quality, and said to be the hest of the Liberian. The juice obtained from trees less than 5 years old is watery, and does not afford such good rubber. Christy considers this a desirable species for cultivation in the lowlands of S. India, Ceylon, Java, Sumatra, Penang, aud Siam.
.A considerable proportion of W. African rubber is obtained from a plant which Holmes has determined to be Taberncemontana crassa. In Senegambia, the anjouan (Vahea senegalensis) contri butes to the supply. In Sierra Leone, rubber is collected from Ficus Brasii ; and some Ficus spp. yield it in Angola on the W. coast, and at Inhambane on the E. A specimen of rubber from the W. coast of Africa is attrihuted to an undescribed species of Carpodinus; and in Reunion, some la said to be derived from Periploca grceca.
The rubbers sold under the general name of African, omitting Mozambique and Madagascar, occur as shapeless lumps ("knuckles ") from the Cungo ; " negroheads " or " balls" of scrap, and smooth cakes, from Sierra Leone ; " thimbles," " nuts," and " negroheads " from the Portuguese ports ; " tongues " from the Gaboon ; and "balla " from Liberia. The African rubbers are more adhesive and less elastic than the Para article, and command a lower price; the inferiority could be much reduced by an improved system of preparation.