252. The TALLOW TREE (Croton sebiferum) is a native of China, and in habit somewhat resembles a cherry-tree, but has shining egg-shaped, and pointed leaves, that form tufts at the extremity of the branches.
The fruit of this tree, from which the Chinese obtain a kind of tallow for the manufacture of candles, is enclosed in a husk, not much unlike that of the chesnut, and consists of three round white kernels. All the preparation that is requisite is to melt these kernels, adding a little oil, to render them softer and more pliant than they would otherwise be. The candles made from this substance are very white, but are sometimes coloured by adding a little vermilion. They are more firm than those of tallow, but not equal in quality to candles either of wax or spermaceti. The wicks that are used are not, like ours, made of cotton, but consist of little rods of light, dry wood, with the pith of a rush entwined round them.
253. INDIAN RUBBER, or CAOUTCHOUC, is the dried juice of a large and much branched tree (Siphonia elastica, Fig. 60), which grows in Guiana, and other parts of South America.
This tree has somewhat oval leaves, entire, veined, and smooth, arranged in threes, and on long foot-stalks.
The flowers are small, in bunches, near the ends of the branches, and the fruit is triangular.
It was not until about the year 1736, that this very extraordinary natural production was made known in Europe. It is obtained by making incisions through the bark of the tree, chiefly in wet weather. From the wounds thus formed the juice flows abundantly. It is of milky-white colour, and is conducted by a tube or leaf, supported by clay, into a vessel placed to receive it. Some writers assert that, on mere exposure to the air, it gradually hardens; and others that, for this purpose, it goes through a certain process, which the Indians keep a profound secret. It is usually brought to Europe in the shape of pear-shaped bottles, which are formed by spreading the juice over a mould of clay. These are exposed to a dense smoke, or to a fire, till they become so dry as not to stick to the fingers; and then, by certain instruments of iron or wood, they are ornamented on the outside with various figures. This done, the clay in the inside is moistened with water and picked out.
Indian rubber is remarkable for the flexibility and elasticity which it acquires on attaining a solid state; and also for the numerous useful purposes to which it is capable of being applied. By the Indians it is sometimes formed into boots, which are impenetrable by water, and which, when smoked, have the appearance of leather. Bottles are made of it, to whose necks are fastened hollow reeds, through which the liquor contained in them can be squirted at pleasure. One of these, filled with water, is always presented to each of the guests at their entertainments. Flambeaux are likewise formed of this substance, which give a very brilliant light; and it is said that a torch of Indian rubber, an inch and a half in diameter, and two feet long, will burn twelve hours. The inhabitants of Quito prepare a species of oil-cloth with the hardened juice of this tree.
The principal uses to which Indian rubber is applied by us are, for the effacing of black-lead marks; for flexible syringes, tubes, and other instruments used by surgeons and chemists; and for the formation, by means of turpentine or linseed oil, of a varnish for air-balloons.
Various experiments have been made to dissolve this substance, so that it may assume its naturally elastic state, under any figure that may be required. This has been effected by means of ether, but the process is too expensive for common use. A simple method of forming tubes of it is to split a piece of cane and to put between the pieces a slip of whalebone. If the Indian rubber be cut into slips, and twisted closely round the cane, and the heat of boiling water be applied, the whole will become united into one piece or tube, from which the whalebone first, and afterwards the cane, may easily be separated.
It has been proved that cloth of all kinds may be made impenetrable by water, if impregnated with the fresh juice of the Indian rubber tree; and that boots, gloves, and other articles, made of cloth thus prepared, may be joined without sewing, and only by moistening the edges with the juice. These are not only more durable, but retain their shape better than such as are made of the juice without any connecting substance.