AMOUNT OF RESIN IN RUBBER 



53 



in Ceylon from Para trees varying from two to thirty 

 years old may be quoted : 



From these results it would appear that the rubber 

 from two-year-old Para trees contains only about 1 per 

 cent, more resin than that from the older trees, and that 

 there is little variation in the proximate composition of the 

 rubber obtained from trees of four years and over. This 

 latter conclusion is also supported by the following analyses 

 made at the Imperial Institute of specimens of rubber 

 from the Federated Malay States which were prepared 

 from Para trees aged four and a half, nine, and seventeen 

 years respectively : 



It must, however, be pointed out that although Para 

 rubber derived from young trees may have the same 

 composition as the product from older trees, as deter- 

 mined by the present methods of proximate analysis, it is 

 usually deficient in physical properties, being soft and 

 weak. As a general rule, therefore, it is not advisable to 

 tap very young specunens of any rubber-yielding plant. 



A further point in connection with the amount of resin 

 in latex is that in mature trees the latex of the branches 

 and twigs may contain more resin than that of the trunk 

 of the same tree. This fact is illustrated by the following 

 results of experiments conducted by Weber on a Castilloa 

 tree in Central America : 



