76 



PARA RUBBER 



Analyses of young Castilloa Rubber, 

 If one studies the many analyses of Castilloa rubber quoted by 

 Weber and the publications of the West Indian Botanic and Agri- 

 cultural Departments, he cannot help being struck with the fact 

 that the quality of the rubber from Castilloa trees depends, 

 in almost every case, on the age of the trees. In some cases the 

 rubber from old trees is shown to contain 82-6 per cent, of 

 caoutchouc and 7 -4 per cent, of resin. The rubber from four-year- 

 old Castilloa trees has been shown to contain 64-1 per cent, of resin 

 as against 8*2 per cent, for twelve-year-old trees. 



The importance of age is further exemplified by analyses showing 

 a gradual decrease in percentage of resinous substances, which occurs 

 with an increase in the age of the part of the Castilloa tree from 

 which the rubber is obtained, the young twigs yielding 5-8 per cent., 

 the large branches 3-77 per cent., and the main trunk only 2*61 per 

 cent, of the resinous bodies. If the rubber contains a very high per- 

 centage of resins, it is usually considered inferior, and is in some 

 cases almost useless. Increase in age is certainly to be associated 

 with an improvement in the physical properties and quality of the 

 rubber, whether one considers plantations of different ages or parts of 

 the same tree. 



Analyses of Para Rubber from different aged Trees. 



100-00 



100-00 



100-00 



Resins extracted by 



glacial acetic acid... 2-74% 



Moisture 



Ash 



Resin 



Proteids 



Caoutchouc 



2-62° 



7o 



2-65°' 



10-12 yrs. old. 30 yrs. old. 



0-20% a.cao/ 



100 • 00 



100-00 



0-50° 

 0-25 

 232 

 3-69 

 93 24 



100-00 



7o 



Nitrogen ..0-28% ..0-48% .. 0-59% 



The above analyses* show the chemical composition of Ceylon- 

 grown Para rubber prepared from trees varying in age from 2 to 30 

 years. It will be noticed that the two-year-old rubber does not differ 

 conspicuously from the older mature rubber. The analyses represent 



Committee of Agricultural Experiments, Peradeniya. M. Kelway Bamber. 



