CHAPTER XI. 

 THE ANTISEPTICISATION OF RUBBER. 



DEFECTS OF PLANTATION RUBBER. 



MANUFACTURERS complain that much of the plantation Para 

 rubber at present received on the market is lacking in " nerve," it 

 works soft between the masticating rollers.and its keeping qualities 

 are far inferior to the Brazilian product. The latter has been known 

 to keep in good condition for sixty years, whereas many samples 

 of plantation rubber have lost their tensile strength in as many 

 weeks. Various reasons have been suggested as the possible 

 cause of these important differences in the two products, such as 



(1) the altered conditions under which the cultivated trees grow ; 



(2) the tapping of too young trees ; (3) the tapping of immature 

 renewed bark ; and (4) the mode of preparing the rubber. 



No great importance attaches to the first suggestion in view 

 of the healthy, robust growth of cultivated trees. Analyses 

 made of the latex from cultivated and wild trees show no 

 striking difference in the chemical composition. So far as 

 cultivated Para rubber is concerned, however, it would appear 

 that the chemical composition of weak and strong rubber, as 

 also rubber obtained from young trees and old trees, is very 

 similar. 



Nevertheless suggestions (2) and (3) certainly merit far more 

 serious consideration, for it is well known that weaker rubber is 

 produced by young trees than by old ones growing under 

 similar conditions, and it has already been shown that the latex 

 obtained from immature renewed bark is poorer in its caoutchouc 

 content than that produced by the original bark. 



It is considered highly probable that in the method of 

 preparation will be found the principal cause of the inferiority of 

 plantation Para rubber as compared with wild Para, so far as 

 the keeping properties of the raw product are concerned. 



