THE SPUEGEWORT FAMILY. 



259 



sively used in many of the Polynesian islands. In the 

 Hawaiian islands the entire kernels are strung on a stick and 

 lighted as candles ; this is also done in India, where the oil is 

 much used. It is imported to this country for candle-making, 

 and is said to be equal to sesame or rape oils. 



Caoutchouc, better known by the name of indiarubber, is 

 the thickened milk sap of trees, principally of the bread-fruit, 

 mulberry, dog's-bane, swallow- and spurge-wort families, the 

 original and still greatest quantities being obtained from 

 several species of Siphonia, a genus of the latter family. They 

 are lofty trees, natives of North Brazil, Guiana, and different 

 parts of Central America, S. elastica being the best known. 

 It is a tree attaining the height of 50 to even 100 feet, and has 

 smooth trifoliate leaves similar in size and form to those of 

 the scarlet- runner. The flowers are inconspicuous, unisexual, 

 and borne in loose panicles. The fruit is a 3-valved capsule 

 bearing 3 nut seeds. It is found throughout the lower re- 

 gions of the Amazon, and is abundant on many islands of that 

 great river. During the wet season these islands are flooded, 

 but as soon as the water subsides they are tenanted by nu- 

 merous Indians and their families, whose occupation is the 

 preparation of caoutchouc. The sap is obtained by making 

 deep vertical and slanting incisions in the bark of the trees, 

 the sap flowing from the wounds follows their downward 

 course, and is caught in vessels at the lower end of the vertical 

 incisions. By exposure to the air the sap thickens and becomes 

 like a creamy paste ; a coating of it is then laid on clay moulds, 

 which are suspended over slow fires. When the first coat is dry 

 a second is added, and so on coat after coat till the required 

 thickness is attained. When the drying is completed the mass 

 is removed from the mould, and is the raw indiarubber of 

 commerce, its blackness being partly owing to the smoke it 

 absorbs whilst drying, and partly by exposure to the air. In 

 Nicaragua and other parts it is made into flat cakes and hung 

 up to dry without artificial heat.* 



* This is chiefly obtained from Gastilloa elastica (page 224). 



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