96 PARA RUBBER. 



first and second instance respectively. This is rather surprising, 

 as the weakness and susceptibility to tackiness so frequently 

 associated with rubber produced by young trees have often 

 been attributed to its high resin content. 



PROTEIDS. 



He found the amount of albuminous matter in rubber 

 prepared from four-year-old and thirty -year-old trees to be 1.75 

 and 3.69 per cent, respectively. It has been frequently suggested 

 that as these albuminoids are largely responsible for the putre- 

 faction which sometimes occurs in rubber, that they should be 

 eliminated from the latex. It, however, seems doubtful whether 

 this would be a wise policy. Spence states :* " That the distribu- 

 tion of the protein mass in the form of a tough fibre running 

 throughout the caoutchouc mass would greatly increase the 

 tensile strength of the latter it seems quite reasonable to suppose, 

 in which case endeavours should be made to secure, by coagula- 

 tion methods in plantation rubber, just such a distribution of its 

 protein constituents as has been shown by the present work to 

 exist in Hevea rubber from South America." 



MINERAL MATTER. 



Both potassic and calcic organic salts are, according to 

 Seeligmann, loc. cit. y found in Hevea rubber, but as the total 

 constituents in the ash rarely exceeds .4 per cent, of the whole 

 product they may be considered as negligible quantities except 

 for their assistance in the identification of particular grades of 

 rubber by chemical analysis. 



EFFECTS OF VULCANISATION. 



In view of the comparatively small market for unvulcanised 

 rubber goods the real value of rubber depends principally upon 

 the properties of the vulcanised product. As different samples 

 of rubber are differently affected during this process it is only 

 possible to determine their strength, power of resistance, 



* Quarterly Journal, Institute of Commercial Research in the Tropics, 

 Liverpool University. 



