138 PARA RUBBER. 



Examples are known of specimens of pure Para Plantation rubber 

 which in two years have resolved themselves into a gummy substance 

 void of all the desirable properties of indiarubber, whereas samples 

 of purified fine hard Para rubber have been perfectly sound after 

 seventy years. The Plantation rubber is usually regarded as 

 wanting in resiliency and recuperative power, but when put on the 

 market as clean biscuit, crepe, or worm rubber, is eagerly bought 

 on account of its purity and, therefore, adaptability for "solution" 

 purposes 



The opinion in many quarters is that the use of chemicals such as 

 acetic acid, formalin, &c, should not be continued if the Plantation 

 rubber can be effectively prepared and purified by mechanical means. 



Burgess , in his report upon a visit to Great Britain to investigate 

 the indiarubber industry and its relation to the growth and prepar- 

 ation of raw indiarubber in the Malay Peninsula, states that the 

 manufacturers who had tried Plantation rubber from Ceylon and 

 the Straits were agreed that the " rubber was good and very service- 

 able, but that it was by no means as good as South American fine 

 Para, either hard or soft cure. The Plantation rubber is lacking in 

 " nerve," it works soft between the masticating rollers, and its keep- 

 ing qualities are inferior to South American Para. After vulcani- 

 zation the tensile strength is less, and the elastic recovery of shape 

 after deformation by stretching or compression is less perfect than 

 South American Para under precisely similar conditions." He 

 further points out that the Plantation rubber shows an inferiority 

 from 8 to 15 per cent, compared with wild Para, and that this 

 inferiority is not only in the physical properties which are capable 

 of immediate measurement, but also in the keeping qualities of 

 the rubber, the plantation samples often tending to become soft 

 and gummy whilst wild Para remains tough and elastic after 

 many years' keeping. Burgess suggests that the superiority of the 

 wild Para may be due to the fact that the rubber trees of South 

 America, which are tapped, areselected both by natural and artificial 

 selection, and therefore only the best and oldest trees are used as 

 sources of rubber. This idea is original, but does not appear to be 

 supported by the results obtained from the old trees at Hcnaratgoda 

 and Peradeniya, where only the first tappings gave tacky or soft 

 rubber, or by the observations quoted by Jumelle. 



The Smoking Method and Plantation Rubber. 



In a recent communication to the Press dated March 22, 1906, 

 Messrs. Lewis & Peat point out that consignments of biscuits have 

 arrived in London in a heated and sticky condition, and raise the 

 query as to whether the present mode of preparing biscuits is the 

 best. It is pointed out that Amazon-grown smoke-cured rubber is still 

 the standard, and has for a record of 50 years maintained its reputa- 

 tion for elasticity, strength , and durability. One of their advisers is 

 inclined to believe that " Ceylon and Straits biscuits and sheets are 



