160 RUBBER AND 



TABLE XXX. 



Loss of weight of rubber samples on washing. 



Trade name Loss, per cent. 

 Para, hard cure 15 



Congo Ball 28 



Ceara (Manicoba) 32 



Borneo 48 



One of the chief merits of plantation rubber from 

 the point of view of the manufacturer lies in its high 

 degree of purity, and the very small loss which conse- 

 quently results when it is subjected to the washing 

 process. In fact, in the near future, manufacturers who 

 deal exclusively with plantation rubber will probably 

 be able to omit the preliminary washing process 

 altogether. 



Owing to the clean character of the latex brought in 

 to the factory on an estate, mere coagulation and drying 

 would lead to the production of a rubber of a higher 

 degree of purity than any wild kind. Washing is 

 necessary however in order to remove the residue of the 

 acid left over after coagulation, together with the soluble 

 constituents of the latex. The latter serve no useful 

 purpose, and are liable if retained to act as nutriment 

 for moulds and bacteria. 



The washing machines employed on estates are 

 generally similar to those used by rubber manufacturers, 

 but are constructed on a somewhat smaller scale. Such 

 machines consist essentially of a pair of heavy steel 

 rollers which revolve in opposite directions. The hand 



