A banana tree, which seemed at first sight to possess all those good qualities—being of a large size, with whitish or flaxen colored fibre, and producing very savoury fruit, only gave 2 per cent, of fibre after preparation; that is to say, 100 lbs. in its raw state, only gave two pounds of fibre after it was boiled. In endeavoring to find out the cause of such a small result, it was discovered that this specimen of banana (commonly called the "pig banana,") contained a larger proportion of water than of fibre, compared with other sorts—that the heart was too large, and that the inside leaves were so tender that they almost dissolved in the process of boiling. These were the greatest inconveniences of this species of tree. There was also another disadvantage, in the quality of its fruit, which was yellow in color, and not so useful as those descriptions of banana which are generally eaten as a substitute for bread. The results of several experiments made upon various descriptions of banana, demonstrated the properties of each species, both as regarded fibre and fruit. The most profitable in both respects is undoubtedly the yellow banana, or common plantain. This tree grows to the height of about fifteen feet, it is nine or ten inches in diameter, its fibre is firm and abundant, and its fruit is used both in a green and ripe state. This plantain abounds on the continent of Spanish America and between the tropics, where the natives cultivate it as producing the most nutritious fruit of its kind. Cargoes of the fruit are frequently exported from Surinam and Demerara. On the Spanish part of the American continent, land is measured by fanegas, each fanega containing twelve quarrees, and each quarree five and one-fifth English acres. A quarree measures one hundred geometrical paces, or three hundred square feet.
In the first instance, the suckers of the plantain (the tree being propagated by cuttings or suckers which shoot up from the bulb), should be set at ten feet distance from each other; this proposition gives 300 plants on one line of trees, or 900 on the surface of one quarree of land. Each plant propagates itself and gives upon an average ten trees of the same size and bearing. On one quarree of land, therefore there would be 9,000 trees, yielding four pounds of fibre and one bunch of fruit each, which is 9,000 bunches of fruit, and 36,000 lbs. nett of fibre, in the whole. In good ground the same plant will last fifteen years without any further trouble. Flat lands ought to be cultivated in preference to any other. The plantain thrives with the root in the water, and the head to the sun. On the borders of the river Orinoco it grows to the height of twenty feet, is one foot in diameter, and the stalks of the branches are three inches in circumference.
Cutting.—The tree which has not produced its ripe fruit ought to be cut, for two reasons—first, that the fruit be not lost; and secondly, that the tree will not have arrived at its full growth and ordinary size, and the fibres will be too tender. In cutting it down, take it off six inches above the surface of the ground, then divide it longitudinally into four parts, take out the heart, which must be left to serve for manure, and if fermentation is decided upon, leave the pieces at the foot of the tree, otherwise take them to the mill to be crushed. The tree being very tender, may, on being bent down, be cut asunder with a single stroke of a hatchet, cutlass, or other convenient instrument. One man can cut down 800 trees, and split them in a day.
Carrying.—The trees being thus divided, may be immediately carried to the mill to be crushed, or may remain until the fermentation separates the juice of sap from the fibres and the pith. By fermenting the trees, their weight will be so much reduced as to render their carriage considerably lighter than if taken away when first cut down. A wagon, with oxen or mules, can carry about a ton per day, and one man can load the wagon and drive the cattle.
Crushing.—If the tree is carried from the plantation without being subjected to fermentation, it must be passed through a mill, the rollers of which, if made about three feet in length, and one foot in diameter, will be found a very convenient size. In this operation, care should be taken, first of all, to separate the tender from the harder or riper layers of fibre. The tree is composed of different layers of fibre, which may be divided into three sorts; those of the exterior, having been exposed to the atmosphere, possess a great degree of tenacity—whilst those of the interior, having been secluded from the air, are much more soft and tender. If, therefore, the layers of the plantain are passed indiscriminately through the mill, those which are hard or firm will not be injured by the pressure, whilst those which are soft will be almost reduced to pulp. Therefore, the rollers of the mill should be always placed horizontally, and upon passing the trees lengthways through the mill, the pressure will be uniform and the fibre uninjured. In this manner, pass the different sorts of layers separately, and the produce will be about four pounds of fibre from each tree. The stalks of the branches of the plantain give the best fibre, and a large quantity, as compared with the body of the tree; 100 lbs. of the stalk will give 15 lbs. nett of fibre. In general, if a tree will give 4 lbs. nett of fibre, the stalks will give 1 lb. out of the 4 lbs. The stalks ought also to be crushed separately, because they are harder than the exterior layers of the tree. About 3,000 trees may be passed through the mill in a day. Whilst the experiments were in progress it was ascertained that with a single horse, 100 plantain trees on an average were crushed in twenty minutes, giving five minutes rest for the horse.
Fermentation.—This operation may be performed in several ways. If the trees are allowed to ferment upon the spot after being cut, a great saving will occur in respect of carriage; this matter ought to be carefully studied, because, on an extensive scale of manufacture, it is of serious importance. It is found that the trees when cut and heaped up, are subject to a drainage of juice, which, having a tanning property, discolors those pieces which lie at the bottom; hence much time is consumed in afterwards restoring the fibre to its natural color. The cut plants should be removed from the stumps of the trees, and then placed in heaps, shaded from the sun by laying the leaves over them. They will take several weeks to ferment. To pursue this process in the immediate vicinity of the establishment, would give rise to many inconveniences, in consequence of the very large space of ground that would thereby be occupied. Fermentation requires a mean temperature. A tree cut down and exposed to the sun, would be nearly dry at about 30 deg. centigrade, showing a result quite different to that which ought to be obtained; whilst a tree placed on a wet soil, and open for the fresh air to circulate between the plants, covered at the same time with its own leaves, and shaded by the foliage of the plantation, would be decomposed at the desired point of about 22 degrees. The different modes of fermentation require the same proportions. If the cut plants be covered with a thick layer of earth, they will not decompose in six months; but if, on the contrary, they are covered slightly, so that they may receive the freshness of the earth, and the heat of the air, they will decompose in six weeks. It is the same with the fermentation of alkaline baths. Baths at only one degree will produce decomposition, whilst baths at three degrees will not produce any decomposition. The stuff after being passed through the mill, or after fermentation, will be put into the chemical baths, or vats, or chemical liquor, and the persons in charge of the mill and boilers will do this work. Fermentation may be advantageously used, in cases where the trees are grown at a distance from the establishment—but, where they are in the immediate vicinity of the works, it will be best to crush them by the mill. The principal saving that is occasioned by fermentation, will be found in the carriage, as the substance will be much reduced in weight by that process. In an establishment where the manufacture is carried on upon a very large scale, trees cut down at a distance can be fermented, whilst those produced near the mill can be crushed.
Chemical Agents.—For decomposing the gluten in the trees during the process of boiling, soda, carbonate of soda, and quick lime, are used. The proportions herein given, are those requisite for making three tons of fibre per day, upon which scale the cost price of the fibre in a prepared state for bleaching, is subsequently calculated. To make three tons of fibre per day, it is necessary to have four boilers of 800 gallons each, and give five boilings in a day, or 1,650 lbs. of nett fibre for each boiler, or 6,600 lbs. for the four boilers per day. After having put into the boiler a sufficient quantity of water to cover the material, wait until the water begins to boil, and then add the chemical agents.
| lbs. | |
| To the first boiling of a copper, put of soda | 60 |
| To the 2nd, 3rd, 4th, and 5th boilings of the same copper, 15 lbs., each making | 60 |
| 120 | |
| Therefore the four boilings will take of soda | 480 |
| The same liquid will serve for two other days,by adding 15 lbs. to each fresh boiling, say, in the whole, 40 lbs., or | 600 |
| It will consume in soda for nine tons made in three days | 1,080 |
| Or 360 lbs. for three tons made in one day. | |
On the fourth day commence again in the same manner, and go on for the two remaining days as above, producing eighteen tons in the six days. The quick lime is to be employed in each of the boilings, in the proportion of one-third less than the quantity of soda. Crude soda may be used in the boilings, without previously discarbonising it, and quick lime reduced to lime water; but, to render the action of the chemical ingredients more quick and certain, it is better to discarbonise the soda before it is put into the boiler. This may be done by preparing in a small separate boiler the quantity of liquid necessary for a day's consumption, which is prepared in about an hour. The carbonisation is effected in the following manner:—
| Ten parts of salt of soda. | } | In weight. |
| Six parts of quick lime. | ||
| Seventy parts of water (never less.) |