THE SCIENCE AND PRACTICE OF PARA- 

 RUBBER CULTIVATION 



THE NEW TROPICAL INDUSTRY OF THE EAST 



By JOHN PARKIN, M.A., F.L.S. 



Part I 



Caoutchouc, 1 the elastic gum prepared by the Indians of 

 tropical America from the milky juice (latex) of certain trees, 

 became known in Europe during the seventeenth century as a 

 curiosity. It remained so in England till the year 1770, when 

 Priestley recommended its fitness for erasing lead-pencil marks, 

 hence the origin of the name " india-rubber," now often 

 shortened to " rubber." 



This substance first assumed commercial importance about 

 the year 1823 through the method of waterproofing patented 

 by Macintosh. Its uses became greatly extended later by the 

 discovery of vulcanisation, a process invented by Goodyear in 

 America in 1839, and independently by Hancock in England 

 about the same period. These pioneers showed that when 

 caoutchouc is intimately mixed with sulphur and subjected 

 to a temperature of about 150 C, its elasticity is not only 

 increased but remains practically uniform through a wide range 

 of temperature ; further, its durability is greatly prolonged. 

 Raw caoutchouc, on the other hand, softens with an increase 

 and hardens with a decrease of temperature. Without the 

 discovery of vulcanisation india-rubber would have remained 

 of quite minor importance ; very little unvulcanised rubber is 

 now used in manufacture. The demand for raw rubber from 

 this time onwards steadily rose. New uses for it were con- 

 tinually being found, and finally the incoming of the rubber 

 tyre, especially the pneumatic variety, has caused an ever 

 growing demand. 



The great basin of the Amazon has always supplied the 

 largest quantity, as well as the finest quality, of this now in- 



1 The word " caoutchouc " is a corruption of the native name for this substance. 



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