270 RUBBER 



subjected to a high degree of heat during the process, not only 

 lost its stickiness, but was able to endure great extremes of 

 heat and cold without deteriorating. 1 



As Vulcan was the god of fire, who presided over the working 

 of metals, this process was called Vulcanization. The more 

 sulphur added, the harder the rubber, and by adding a suffi- 

 ciently large quantity a solid black substance is obtained, 

 called vulcanite or ebonite. Vulcanized rubber, it was found, 

 could be used for a very great many purposes, and from this 

 time forward the demand for it increased enormously. 



There are a great many different kinds of trees which 

 produce rubber, altogether about a hundred, and they all grow 

 in hot climates. The forests of the Amazon Valley and of 

 the Congo were for a long time the chief sources of supply. 



The methods of the native collectors were primitive and 

 extremely wasteful. More often than not the trees were killed, 

 and the collectors had to probe more and more deeply into the 

 forests to obtain supplies. (Some of the South American 

 rubber has to travel 3,000 miles before it is put on board 

 ship, and it does not reach us till a year after it has been 

 gathered.) 



The very best rubber of all is obtained from the tree called 

 Hevea brasiliensis. It grows in the Amazon forests, and is 

 especially vigorous and abundant on the plateau between 

 the Tapajos and Madeira Rivers in Brazil. 



Sir Joseph Hooker, at that time Director of Kew Gardens, 

 ardently desired to obtain some seeds of these trees, and to 

 plant them in suitable regions of the empire, so that in course 

 of time we might produce our own rubber. 



It was a great idea, but almost insuperable difficulties stood 

 in the way of its realization. To begin with, the seeds remain 

 good only a short time after they fall from the tree (it is best 

 to plant them within a week), and therefore it is not surprising 



1 By accident Charles Goodyear, who was experimenting in rubber, 

 dropped some of it on a hot stove and found to his surprise that it did not 

 melt. 



