62 



AMOUNT OF RESIN IN RUBBER 



It will be seen from these figures that there is a gradual 

 diminution in the proportion of resin from 42' 3 to 7*2 

 per cent, as the trees increase in age. 



The followmg figures, illustrating the same point in 

 connection with Castilloa trees growing in Trinidad, have 

 been published by the Department of Agriculture in 

 that Colony : 



Analyses made at the Imperial Institute of a number 

 of specimens of Castilloa rubber from Trinidad and 

 Tobago have also shown a general diminution in the 

 percentage of resin as the trees increase in age ; but, as 

 will be seen from the following figures, the rubber of older 

 trees sometimes contains more resin than that from 

 younger plants : 



In the case of Para trees, however, the composition of 

 the rubber is much less affected by the age of the trees, 

 and the following analyses by Bamber of rubber derived 



