Adansonia digitata—Baobab or Monkey-bread.—Exogen ; tree. Native of W. Africa, notably about Sierra Leone, Angola, Loando, Senegal, and Inner Africa ; long been naturalized in India, but fouud only in two districts of Bengal at Hazareebaugh, scarce, and at Nowgong, wild. Two acres have been experimentally cultivated at Calcutta. The fibrous bark is obtained in the following manner :—The hard outer bark is first chopped away all round the tree, after which the inner bark is stripped off in large sheets. These are beaten soft with sticks, and shaken to remove the pithy matter. The fibres are then dried in the sun, and pressed into bales for shipment. Small trees produce finer and softer fibrea than large ones. They are said not to miller much injury from the treatment, and to replace the bark in 6-8 years ; but this appeara very doubtful. The fibres are very strong, and are used by the Africans for making rope, twine, and sacking. In India, they are in repute for elephant ropes. Quantities of the bark have been imported into this country from Portuguese W. Africa, and met with ready sale to paper-makers, at 91.-151. a ton. It produces an exceedingly strong paper, suitable for bank-notes, and has, on this account, received much attention ; but the very aloes growth of the tree, and the careful cultiva tion and shading it requires while young, render it a very precarious source of paper fibre, under these conditions. On the other hand, it seems to coppice well, sending up shoots of 10-12 ft. in height in a year. It is suggested that, when the trees have reached a fair size, they should be coppiced annually, after the manner of osiers.
Agave americana—Century-plant, Mexican or Spanish aloe (Fs., Pite, aloes; MEX., Pita, Maguey). —Endogen ; 24-36 ft. Indigenous to all parts of tropical America, from the plains to 10,000 ft.; now naturalized in S. Europe, Mauritius, Algeria, throughout India, and the Pacific Islands. The plant requires about 3 years to come to perfection, but it is exceedingly hardy, easy of propagation, very prolific, and grows in arid wastes where scarcely any other plant can live. It perishes after infloreseenee, which does not occur till the 8th-20th year, but it then sends up numerous shoots. In Mexico, 5000-6000 plants may be found on an acre. The average number of leaves is 40, each measuring 8-10 ft. long and 1 ft. wide, and yielding 6-10 per cent. by weight of fibre. The culture of the. plant is being extended in America, but not in the proportion which its value deserves. In India, it is all but neglected; it grows wild in many parts, and is sometimes cultivated as a hedge-plant, but its fibre, seldom and badly prepared, is harsh and brittle, though of good colour. Care would effect great improvements.
The native methods of preparing the fibre are very primitive :—(l) The leaves are cut, and steeped in water ; then beaten with sticks, and rubbed with stones, or scraped with shells or wooden blades, to remove the non-fibrons portion ; and finally washed, and bleached in the sun. This
plan causes stains, and a tendency to rot, and thus reduces the value of the fibre. (2) The leaves are cut, and deprived of about 6 in. of the pointed end ; then well beaten or bruised with wooden mallets on a smooth surface of stone or wood, tied in bundles of 4 leaves, and laid in heaps to ferment. The beating removes much of the sap ; and the fermentation helps to loosen the fibre, without damaging it. When the heat has subsided, the bundles are thrown into water, and steeped for about a fortnight; after washing, the fibre appears clean and white. It is then dried, shaken, and packed.
The process of retting has been proved injurious to the fibres of all endogens, and mechanical contrivances have been invented for separating the fibres from the leaves of the agave, and similar plants. In employing the machines described below, an abundant supply of water is a matter of great importance, as its copious use expedites the process, and ensures a fibre of good colour and strength. The leaves should be cut before they are overripe: it is preferable to cut them too soon rather than too late, as over-ripe leaves produce coarse fibre of inferior colour. They should be put through the first process immediately after they have been cut, as the longer they are allowed to lie before crushing, the more difficult is the separation of their fibres.
Fig. 626 represents the crushing machine. It consists of a cast-iron framing a, in which are placed two vertical iron rolls b, slightly conical, and baying their surfaces grooved, to facilitate the gripping of the leaves. One roll revolves in fixed bearings ; the bearings of the other roll are fixed in a sliding frame, the centre of which works in and out of a hollow trunnion, in which is placed a strong volute steel spring, which cp-n be set by a hand wheel d, ao as to regulate approximately the elastic play given. Both rolls are driven by gearing fixed in the bottom part of the framing of the machine, the wheel which drives the sliding roll being set free to move backwards and forwards on the driving shaft, by means of a feather on the shaft.
The leaves are passed singly edgeways through the rolls, and the pressure thus applied squeezes out the juices and non-fibrous parts. Two water-taps c are fixed on the framing of the machine, in such a manner that each aide of the leaf has a jet of water applied to it at the moment of pressure, in order to wash away the juice, &c., which exudes ; below the rolls, is a copper guard, which catches the water, juices, &c., and conducts them into a drain beneath the machine.