I0 6 PARA RUBBER. 



therefore contains a percentage of pure rubber exceeding that of 

 every known rubber quality. 



" Its only impurity consists of about 2 per cent, of a viscous 

 resinous matter, the removal of which is scarcely worth while." 



The smoking method employed by the rubber collectors in 

 Brazil produces an article which, although sometimes con- 

 taminated with dirt, is practically free from putrefaction and 

 mould, as creosote and carbon in the smoke act as antiseptics, 

 and prevent their developing. 



Alum is largely used as a coagulant, but its use is objection- 

 able, as rubber prepared by it perishes, owing to the action of 

 the alum upon the rubber forming a resinate of alumina. 

 Manufacturers state that rubber coagulated by it when placed 

 on the market often contains as much as 6 per cent, of alum. 



Common salt is also largely used, and although it possesses 

 antiseptic properties its use should be condemned, as it tends 

 to leave a large quantity of moisture in the rubber. 



The employment of chemicals for the coagulation of rubber 

 is apt to seriously injure the product, and therefore cannot be 

 recommended, notwithstanding the fact that Para rubber ex- 

 ported from Ceylon and the Straits Settlements has realised 

 excellent prices ever since it was first placed on the market, and, 

 in fact, nearly always in advance of the finest rubber from Para. 



Prepared in the manner described, it must contain the 

 constituents which support mould and fermentation, or, in other 

 words, it lacks what is probably the most important character 

 to which the Brazilian product owes its reputation. This 

 character, as we have previously pointed out, is imparted to the 

 product by the smoking process employed in preparing the 

 rubber. 



This process is, however, much more tedious than the Ceylon 

 one, as will be seen on comparing the two. The Brazilian 

 collector takes a paddle, dips it in the latex, and holds it over 

 the smoke of a fire fed with wood and palm nuts, or if the 

 latter are not obtainable, with the former alone, until the rubber 

 coagulates and dries. This performance is repeated again and 

 again until the rubber has grown to the required size. 



By the Ceylon method all that is necessary is to pour the 

 latex into saucers, press out the moisture when it has coagulated, 

 and lay the coagulum out to dry. 



