RUBBER HAND STAMP MAKING
AND THE MANIPULATION
OF RUBBER.
CHAPTER I.
THE SOURCES OF INDIA RUBBER AND ITS HISTORY.
India rubber or caoutchouc is a very peculiar product, which is found in and extracted from the juice of certain trees and shrubs. These are quite numerous and are referred for the most part to the following families: Euphorbiaceæd, Urticaceæd, Artocarpeæd, Asclepiadaceæd, and Cinchonaceæd. It is evident that a considerable number of trees are utilized in commerce for its production, and it is certain that it exists, quite widely distributed, in many cases as a constituent of the juice of plants not recognized as containing it.
When an india rubber tree is tapped, which is effected by making incisions in the bark, the sap of the tree exudes. It is a milky substance and is collected in various ways; it may be in vessels of clay, in shells, or in other receptacles by the india rubber hunters. If this substance is examined it is found to be of very remarkable and characteristic constitution, resembling in its physical features ordinary milk. It is composed of from fifty to ninety per cent. of water, in which is suspended in microscopic globules, like the cream in milk, the desired caoutchouc or india rubber. If the juice is left to stand in vessels, like milk in a creamery, the globules rise to the surface, and a cream of india rubber can be skimmed off from the surface. If the juice is evaporated over a fire, the water escapes and the india rubber remains. By dipping an article repeatedly in the juice and drying it, a thick or thin coating of india rubber can be developed. Before the modern methods for the manipulation of the gum had been developed, and before the invention of vulcanization, this method was adopted for the manufacture of shoes. The original “india rubbers” for protection of the feet in wet weather were made in this manner. A clay last was used, upon which the india rubber was deposited as described. The clay last was then broken out and removed. Great quantities of overshoes were thus made in South America, and many were exported to Europe.
When caoutchouc has once been removed from this watery emulsion, which for all practical purposes is a solution, it cannot be restored to the former state of liquidity; it remains solid. It will absorb a considerable quantity of water, but will not enter again into the quasi solution or combination. This property of permanent coagulation, which interferes to a degree with its easy manipulation, was early discovered. In the last century quantities of the natural milk were exported to Europe to be used in what may be termed the natural process of manufacture, because once solidified it could not be redissolved, and because the manufacturers of those days had not the present methods of dealing with the apparently intractable gum.
The natives of South America before the advent of Europeans, were familiar with the treatment of the juice by evaporation just described and used to make bottles, shoes and syringes of it for their own use. The name Siphonia applied to several species of rubber tree, and seringa (caoutchouc) and seringari (caoutchouc gatherer) in Spanish recall the old Indian syringes and tubes.
The gum is now collected for export in many parts of the world. South and Central America are, as they have always been, the greatest producers. Some is collected in Africa, Java and India. The best comes from Para. However carefully treated a great difference is found in the product from different countries. The Brazilian india rubber, known as Para, from the port of shipment, ranks as the best in the market.
Its history as far as recorded, does not go back of the last century. Le Condamine, who explored the Amazon River, sent from South America in 1736 to the Institute de France, in Paris, the first sample of india rubber ever seen in Europe. He accompanied the sample with a communication. He said that the Indians of that country used the gum in making several domestic objects of utility, such as vessels, bottles, boots, waterproof clothing, etc. He stated that it was attacked and to a certain extent dissolved by warm nut oil. In 1751 and 1768 other samples were received through MM. Fresnau and Maequer, who sent them to the Academy of Sciences, Paris, from Cayenne in Guiana.
Although from this period numerous experiments were tried with the new substance little of importance was done with it for many years. Its first use was to rub out pencil marks, whence it derived its name of “india rubber.” As late as 1820 this continued to be its principal use.