Rubber

Rubber, a convenient collective name for those mixtures of hydro-carbons with an oxidised substance, found in the latex (q.v.) of most plants, which are pliable and are insoluble in water, alcohol, or unconcentrated acids. Only within the tropics, between the isotherms of 70° F., where the annual rainfall is about 90 inches, do the trees produce this latex in abundance. The chief kinds in commerce are (1) "American," including Para, Carthagena (from New Granada), and Ceara; (2) "West Indian," including Guayaquil (from Ecuador), Pernambuco, Maranham, Nicaragua, Honduras, and Guatemala; (3) "Asiatic," including Singapore, Assam, Penang, Java, Siam, and Borneo; and (4) "African," including Madagascar and West Coast. Of these, the Para, or Cahout-chou, from the Amazon valley, is the most valuable. It is the produce of various species of the euphorbiaceous genus Hevea (Siphonia). Carthagena, Guayaquil, Nicaragua, Honduras, Guatemala, and other West Indian or "Ule" rubbers come from Castilloa belonging to the Bread-fruit family. Ceara rubber is derived from the euphorbiaceous Manihot Glaziovii; that of Pernambuco from Hancorna speciosa, belonging to the Periwinkle family; the "Gutta sussu" of Borneo and the "Gutta singgarip" of Malaysia, from species of Willughbeia; and African rubbers from species of Landolphia and Vahea, all belonging to the same family. The caoutchoucs of Assam, Sylhet, and probably Singapore, are the produce of species of Ficus, of which F. elastica is the best known. Though indiarubber has long been known, the discovery of the process of vulcanising gave so great a stimulus to the trade in it that this trade may almost be said to belong to the last quarter of a century. Exclusive of guttapercha (q.v.), our imports of raw rubber have grown as follows: -

1830 - 464 cwt
1840 - 6,640 cwt
1850 - 7,616 cwt
1860 - 43,039 cwt
1870 - 152,118 cwt
1880 - 169,587 cwt
1890 - 264,000 cwt

Nearly half of the import now comes from Brazil, the Gold Coast and Bombay contributing the next largest amounts. The United States now imports as much as we do, and our exports of manufactured rubber are valued at nearly millions sterling annually. [Caoutchouc]