Legal restrictions now prevent the abusive treatment of the forests of rubber trees. They may not be cut down, as formerly permitted, and tapping must be done at stated intervals, to let the trees recuperate from the exhaustion they suffer. At present the simple natives, who do the work of gathering crude rubber, are under the control of syndicates which have concessions from the countries in which the trees grow. The work is hard and the pay small, at best; but cruel treat ment, even atrocities, have been committed by overseers, to extort more wealth for the company. The African, Peruvian, and Central American forests have been the scenes of such abuses. Investigations that have given publicity to the facts will doubtless soon lead to their correction.
Between the native, who gets scant pay for crude rubber, and the consumer, who pays an extravagant price for one tire for his automobile, and but half of that rubber, there is a tremendous profit for the maker and the seller. No wonder people get excited on the subject of rubber planta tions, and invest recklessly in shares in such schemes, for the suave "promoter" can easily prove that there is money made in the rubber business.
From Brazil, rubber culture has spread and become established in all important countries in the Tropics. Investigations have determined just the trees and other plants that produce rubber in paying quantities. The best methods of harvesting the crop have been tested, and are being established to replace worn-out, wasteful methods.
Crude rubber is the coagulated milky juice of several trees, chiefly of the Euphorbia tribe, or family. It is produced in a network of passages that lie in the bark, near the cambium, or liv ing layer, that separates wood and bark. To get the fluid, the trees are tapped, and the flow led into cups that are emptied at regular times, and the sap treated, without delay, to hasten the coag ulation of the caoutchouc, and to evaporate the watery part.
The harvesting of rubber has in late years inter ested even the uncivilized tribes, now the slaves of the Rubber Companies; for they realized that it was bad business to abuse or kill the tree that produces rubber. To get the greatest quantity of rubber with the least injury to the tree is the modern problem.
The oldest method of tapping was to cut troughs down the four sides of the tree, and catch in some crude way the flow of sap. Then the plan was to cut four V's as high as the reach of a man standing by the tree. A cup was fastened at the point of each. Other V's cut at intervals drained the area
below. This overtaxed the trees.
The method in general use now in harvest ing Para rubber is the herringbone system. A vertical trough is cut with alternating side troughs, slanting at 45 degrees and about a foot apart. The cup set at the base of the main trough catches the flow. Each day, when he comes to empty the cup, the collector cuts a thin slice of bark from the lower edge of each lateral trough. This opens the clogged passages, and renews the flow. The daily cutting is repeated until the side troughs are nearly two inches wide, or until de crease in the flow indicates that the tree is drained. Six months of rest allows the tree to heal its wounds, and reestablish the network in which the milky juice is found.
The spiral system, a winding trough around the trunk, is a new that gets the greatest flow of sap. Whether it is best for the tree re mains to be seen. A plan to prick the bark, puncturing the net-veins but not going deep enough to injure the cambium, is a perfect method; but the collecting of the flow is the difficulty. Such treatment would not hurt the trees, if done on alternate days. It might go on for years.
Tapping on rainy days and early in the morning induce the greatest flow, for the heat of the sun causes the juice to coagulate and stop the passages. Young trees and trees too heavily drained yield rubber of poor quality. So do the upper parts of trunks and the limbs. These facts are known to the greedy rubber gatherer, and it saves the tree from many abuses.
Para rubber comes from a tree called Hevea Braziliensis, that grows wild in different parts of the silvas of the Amazon, and in Peru, Bolivia, and Guiana, a total area of millions of square miles. Para is the port from which most of it is shipped. Brazil furnishes the world about half of its rubber supply — exports amount to fifty-four million pounds a year. Not all of this is Para quality.
Because Hevea trees produce the highest quality of rubber, they have been planted where new plantations are desired. They are estab lished in the West Indies and Trinidad, and in Ceylon and the Malay Peninsula, where English companies have started great plantations. Be tween 1900 and 191o, Para rubber rose in price from three shillings to twelve shillings per pound! It costs about one shilling per pound to collect from the wild or to produce in plantations. The price fluctuates in the hands of speculators, quite independent of supply and demand.