142 PARA RUBBER. 



are very liable to become heated or tacky. He argues that " the 

 very form of thin biscuits lends itseif to heating when under pressure , 

 whereas the ball shape and thick biscuits are far less liable to this 

 change, and he prophesies that when the rubber is arriving in tons 

 the defects will be very evident by the state the material arrives in , 

 and that even if the rubber does not get heated on the voyage it will 

 inevitably do so if stored for any length of time in the warehouse. 

 He gives as proof of his theory that the same thing occurred to 

 certain other rubbers, and the remedy in their case was making it 

 into large balls." 



Sheets measuring 24 x 12 inches and §- to ^ inch in thickness are 

 received with favour in Europe. 



Size and Shape, &c, of Biscuits. 



[n many instances the biscuits, on drying, curl up at the edges 

 and present an objectionable appearance. This can to some extent 

 be overcome by pressing them in a vessel of definite outline 

 before subjecting them to the rolling process ; after rolling, the 

 cakes partake of the shape of the vessel in which they were pressed, 

 and if the margins of the latter are correctly made the tendency to 

 curl and become wavy in outline is not as noticeable. 



The biscuits and sheets are usuaUy very pure, and can without 

 washing be used for " solution " work by the manufacturers ; the 

 material is practically ready for the naptha bath on its arrival in 

 Europe. It has been stated that the material from Ceylon shrinks 

 about 1 4 per cent. , and that it is not liked for cements. In past times 

 it has been very irregular in quality, sometimes being little better 

 than elastic gum , sometimes sticky and only equal to recovered rubber 

 in elasticity. The rubber biscuits from old Para trees are tough and 

 elastic, and much of the irregularity referred to might to some extent 

 be obviated by not mixing the tappings from trees of different ages. 

 If the irregularity in quality is allowed to continue, it may spoil 

 all prospects for use of our rubber in fine work, such as thread, blad- 

 ders, &c, and if the ''solution" market should become overstocked 

 the position might under such circumstances be embarrassing to 

 rubber planters in Ceylon and the Straits. 



Biscuits should be made from §• to £ inch in thickness and 12 to 

 14 inches in diameter. 



Crepe Rubber. 



Crepe rubber differs from the foregoing on account of the stretch- 

 ing and tearing it has undergone between the rollers of the washing 

 machine and the low quantity of soluble and mechanical impurities 

 it contains. It is, of course, only washed rubber, but it may have 

 been obtained from purified scrap as well as the other class. It has 

 an irregular surface, is very uneven in thickness, and like lace and 

 flake rubber dries very rapidly. On account of its purity it has been 

 well reported upon in Europe, and owing to the efforts of Burgess is 

 likely to come to the front in the Straits. Crepe rubber has been 

 described in Europe as "fine pale, strong, quite clean, and in good 



