There are in the world very many plants and trees yielding rubber of differing qualities. Three kinds of elastic gum are exported from Brazil in addition to the latex of the _heveas_: they are known as mangabeira rubber, from _mangabeira hancornia speciosa_; maniçoba, from the _manihot_ plants of several kinds (euphorbias, and first cousins of mandioca); and caucho, drawn from the _castilloa elastica_ tree. All these have their places in world markets, but, as also in the case of balata from the Guianas, and the gum of the guayule shrub in Mexico, it is not upon these rubbers that the great manufacturing industries of the world are based. That distinction belongs to the _heveas_, native dwellers of the deep, hot Amazonian valleys. The elastic, resilient, waterproof properties of rubber were first discovered by the native children of the Americas, both in South and Central America and Mexico. When Hernan Cortés took his handful of conquering Spaniards into Mexico he found the Aztecs playing a game with bouncing balls made from _castilloa_, but during three centuries the Europeans visiting the New World did not dream of turning the gum to any utilitarian purpose. The first traveller who took recorded note of native use of rubber for water-proofing was the French scientist, de la Condamine, who came to Peru and travelled down the Amazon in 1743. He took specimens of what he spelled as “caoutchouc” back to Paris. In 1779 Priestly noticed that the gum would erase pencil marks on paper; small pieces were sold for this purpose, and as the chief supplies came from the East Indies (from the _ficus elastica_) the name India-rubber clung to the product. In 1823 Charles Macintosh found that rubber was soluble in benzine, and so led the way to its commercial adaptation—thinned out, spread into sheets, rendered amenable; the idea applied to waterproof coats immortalized his name. In 1832 the Chaffee & Hoskins firm, founded in the United States, began manufacturing water-resisting objects, and thus laid the foundation of the present great rubber business in North America; their company, the Roxbury India Rubber Co., had in its employ a young man named Goodwin, and when this experimenter discovered that the gum would resist great extremes of heat and cold when sulphur was mixed with the solution, the process of “vulcanization” was the result, and rubber was made applicable to a score of new uses. Its great commercial employment dates from this time.