Popular Science Monthly/Volume 18/January 1881/Oil-Plants of French Guiana
By Dr. J. HARMOND.
THE flora of Guiana includes a considerable number of plants of different families whose organs contain fatty matters. The most important of these plants, both on account of the abundance and quality of the oil it yields, is the carapa (Carapa Guianensis, D'Aublet; Xylocarpus carapa, Spr.; crabwood of the English), a plant of the family of the Meliaceæ, the family of which the Pride of India is the best known representative. It is one of the largest trees of the country, reaching a height of from sixty-five to a hundred feet, and a diameter of from a yard to a yard and a half. The wood is of a grayish or reddish color, and of excellent quality, is much in demand on account of the ease with which it is worked, and is used for shingles, cabinet, carpenter's and carriage work. The leaves are abruptly pinnate, with smooth, oval leaflets about a foot long and ending in a projecting point. The fruits are round, four-valved capsules, about three inches in diameter, and grow in bunches. They inclose a white, solid kernel of irregular shape and firm consistency. To get the oil, the natives boil the kernels in water and let them stand in a heap for a few days. They then peel them, crush them with stones or pound them in wooden
Fig. 1.—Carapa Guianensis Fruits and Leaves (reduced).
mortars, and make a paste of them which they spread on a slab of stone hollowed out, and exposed at a slight inclination to the heat of the sun. The oil with which the paste is impregnated runs into a calabash which is placed to receive it. The negroes on some of the plantations put the paste into a bag and press the oil out with weights. The carapa-tree appears to have been formerly more, abundant in the inhabited districts than it now is, but it has been sought after on account of the qualities of its wood till it has nearly disappeared. It is still very abundant in the interior, where it grows near the rivers, and on moist lands. In some places, it is said, the ground is so thickly covered
Fig. 2.—Omphalea Diandra (D'Aublet). 1, 2. Fruit, splitting into three nuts; 4. Internal face of cotyledon; 5. Nut with a part of the shell taken away, showing a part of the kernel.
with the fruits that they come up to the knees of a person walking among them. The principal crop is gathered between February and June or July. Another crop ripens in September and October, but the oil is of an inferior quality. The fruits do not keep well, but are subject to a mold which reduces them to dust, sprout readily, and are greedily attacked by a grub and by microscopic enemies. The paste, too, is apt to spoil by heating. Hence it is found to be most economical to make the oil where the nuts grow. The nuts, when broken up with their coverings, yield about thirty-six per cent, of oil; cleared of their coverings, the kernels give sixty per cent. When cold-pressed, the oil is clear and amber-colored. When left to stand, it gives a solid deposit of a crystalline appearance. It makes a soap of excellent quality, and having a certain degree of hardness—a property which makes it valuable to mix with other oils that give too soft soaps. When refined, it makes an excellent lubricating oil, and gives a light that leaves nothing to be desired. The catalogue of the Permanent Exposition of the French Colonies names some fifteen other species of plants the fruits of which yield oils. One of the most valuable of them is the Omphalea diandra (D'Aublet), a large vine of the Spurge family, which bears seeds with very hard and black, horny shells. The shells are used for making beads. The kernel contains a very limpid, amber-colored oil, which is excellent for illumination, for making soap, and for lubricating purposes, and of which the yield is 64·58 per cent.