t 



Assam and Burmah. It is the hardened latex obtained from 

 various families of tropical plants, both trees and shrubs, while 

 guttapercha is the hardened latex from large trees belonging 

 to one family only, viz., Sapotaceae. Both India-rubber and 

 guttapercha consist of carbon and hydrogen. India-rubber 

 does not soften in moderate heat like guttapercha does. 

 India-rubber is impervious to water, alcohol, most acids and 

 gases and it retains for a long period its original elasticity 

 and strength ; while guttapercha becomes soft and plastic 

 in hot water retaining any shape given to it on cooling when 

 it becomes hard and rigid. 



786. The most important India rubbers are : 

 (i) Para rubber. This is obtained from Hevea Brasi- 

 liensis, a South American tree which grows in Ceylon. 

 Para rubber does well in Ceylon in low elevations in 

 certain districts, but not so well as in the Straits Settle- 

 ments or in America. It is ready for tapping in 15 

 years. The tree attains a height of 60 ft. and a girth of 

 6 to 8 ft. The wood is poor, soft and easily perishable. The 

 seed is very oily and on this account easily gets rancid and 

 spoilt. But it went from Ceylon to Kevv Garden all right 

 packed in canvas bags only, and it travels better packed in 

 moderately dry soil or cocoanut fibre. It is propagated also 

 from cuttings and stools or green shoots. The tree grows in 

 well drained soils beyond the reach of floods, although in 

 South America it flourishes in unhealthy localities which get 

 annually inundated and swamped. The latex is alkaline and 

 the addition of a solution of ammonia preserves it indefinite- 

 ly from spontaneous coagulation. In favourable localities, 

 120 to 140 Ibs. of para rubber are obtained per acre per 

 annum after the loth year. The tapping commences 

 sometimes on the 6th year, when each tree yields about 

 10 ounces. If 300 trees are planted per acre as much 

 as 1 88 Ibs. can be obtained out of an acre from 6-year- 

 old trees, but 300 per acre (i.e.) when they are 12 ft, apart) 



