The Story of Rubber

By

RUBBER DOWN THE AGES

It is believed by many that Christopher Columbus saw the natives of Haiti playing games with balls which, he discovered, were made from the gum of a tree.

That occurred during his second voyage to the New World, 1493-1496; and the Spaniards, afterwards were not slow in learning how these natives collected and manipulated the curious tree-milk. When we come to the year 1615 we find records which state that Spanish troops in Mexico wore rubber-proofed cloaks to protect themselves from the rain - but not from the sun's rays, which melted the coating of rubber.

Before man could process rubber and make it stand up to the sun's rays, over 200 years were to elapse. The interim stages of development through which he achieved that result are full of romance and interest.

Nature predisposed her rubber-producing plants over a wide area – for they occur not only in South and Central America, but also in Africa and many part of Asia. The ancient philosophers and alchemists must have known rubber, but more as a curiosity than a product having a specific use. Europe was to wait until the year 1736 for the first appearance of rubber.

When the Academie des Sciences sent an expedition to Peru to measure an arc of meridian, one member of the party, Charles de la Condamine, succeeded in the meritorious feat of tracing the mighty Amazon River as it flowed from Quito to Peru, seat of ancient civilisations. En route, he collected samples of rubber, which he sent to Paris, together with a complete description of the rubber tree, and the native's [sic] method of making rubber-proofed garments, shoes, bottles and other articles, by coating fabrics or clay moulds with the milky sap from a tree, drying off each coat over a smoky fire.

Thus, through Condamine, rubber came to Europe during the 18th century, marking the first epoch in the history of the product. Portugal and Spain were at fault for rubber's tardy arrival, for in addition to the discovery of Columbus, they were in possession of the vast rubber forests of the western hemisphere. Neither country made any attempt to ship rubber to Europe.

Let us take a brief glimpse at the raw basic materials, as supplied to the rubber industry today, for conversion into those daily needs which you take so much for granted. First there is the rubber-tree milk called latex (pronounced lay-tex); as it drips' from the slit bark of the tree it contains about 60 per cent water, 28 percent chemically pure rubber, and 12 per cent resins, proteins, sugars and mineral matter. The rubber is suspended throughout the milk in the form of minute globules, of which there are about 7,000,000,000,000 in one cubic centimetre of milk. Within a few hours of its collection from the trees it must be " preserved " by adding ammonia to it, or it would "turn" and curdle, just like cows' milk does when it is not kept cool. Thus preserved, it travels in tanks from the rubber plantations, to places all over the world. Second, and more important today, but only from the standpoint of quantity, is the dry rubber made from the latex, on the plantations, by diluting it with water and adding acetic or formic acid. This curdles or coagulates the rubber which rises to the top as thick, water-logged slabs; these are bailed out and squeezed through rollers, just like passing wet clothes through a wringer. Finally, the rubber is completely dried, before shipment abroad in bale form, either by the hot-smoke process which takes 48 hours and gives amber-brown, smoked-sheet rubber, or by the ordinary air-drying process which takes two weeks and gives almost white crepe rubber.

The number of years devoted to improving primitive methods of processing rubber make up the second epoch. In those early days, vulcanisation was not known and the main object was the discovery of a liquid which would readily dissolve the gum. Only the natives and colonists who lived near enough to the rubber-bearing trees could use the fresh, liquid milk. When once this had soured the clotted gum proved difficult to work. Unlike dough or plasticine, the gum was not plastic enough to be moulded. The obvious thing, therefore, was to try to dissolve the solid rubber in some liquid, and use the solution as the natives used the virgin milk...

The first thing tried was turpentine, then purified ether. In 1791, it was discovered that rectified petroleum dissolved the gum. Meanwhile, the principal use for rubber, suggested by the French in 1752, seemed to be for erasing pencil marks. It is also re- corded that a famous English chemist, Joseph Priestley (who discovered oxygen), once stated that " india rubber," " a substance excellently adapted to the purpose of wiping from paper the marks of a black lead pencil," could be purchased from Mr. Mairre, an instrument maker opposite the Royal Exchange in London. The price was three shillings sterling per half-inch cube.

This was probably the earliest commercial use of rubber and the true derivation of the colloquial term,'" rubber." "Indian," and later, "India," implied the sour of the material, the land of the Indians.

Contrast the bulk of that three shilling cube with the tonnage used, say, in the construction of a rubber roadway. The modern world has discovered numerous uses for rubber demanding vast quantities of the material in many forms.

William Murdock's experimental use of coal gas for lighting his house in Redruth, in 1792, was followed ten years later by the adoption of this means of illumination in the London Soho foundry of Boulton and Watts. Very soon, gasworks were being built all over Britain, and the disposal of the by-products of gas manufacturers had become a real problem. Coal tar naphtha became available and cheap, and once it became known that it was an efficient solvent for rubber, the fertile seeds of a famous industry, Rubber Proofing, were sown.