IO2 PARA RUBBER. 



The following is the oldest method adopted in the prepara- 

 tion of Para rubber on some of the rubber estates in Ceylon : 



Immediately the latex is brought in from the plantation 

 it is strained through fine wire or muslin gauze, the latex being 

 diluted with water if it is too thick to pass through freely, and 

 poured into enamelled iron saucers about I foot in diameter, and 

 i-J- inch deep. 



Coagulation occurs spontaneously within twenty-four hours 

 if the latex be exposed to the atmosphere. But if it be wished 

 to hasten the process, acid is applied ; acetic being one of 

 the commonest employed. The coagulum is then submitted to 

 pressure, in order to free it from as much moisture as possible. 

 A metal roller, similar in shape to that used for culinary purposes, 

 is generally employed, and in the manner shown in Fig. 16. This 

 process converts the rubber into flat discs, which vary in thickness 

 from an eighth to half an inch, and about a foot in diameter. 

 These are then usually submitted to a little artificial heat, and 

 afterwards spread out singly on shelves in a well-aired room until 

 thoroughly dry. 



Fig. 17 shows rubber biscuits spread out to dry in a curing- 

 house on the Aropolakande Rubber Estate, Ceylon. 



The rubber planters in the Malay Peninsula adopted a very 

 similar method to the above. 



Dr O. Weber,* who devoted considerable labour to the 

 chemical questions relating to india-rubber, suggested the 

 following process to eliminate putrescible nitrogenous matter 

 from latex : 



" The first step in this direction is the dilution of the crude 

 latex with water, of which at least five times the volume of the 

 latex treated should be used. In the case of the thick, ready 

 latex yielded by the trees at Las Cascadas it is preferable to use 

 actually boiling water, but in how far this applies to the latex 

 obtained in other districts or from different trees is a matter for ex- 

 periment. Boiling water at once converts this latex (i.e., Castillod] 

 into a thin,veryfluid milk, which through a common cotton gauze is 

 strained in order to remove from it any insoluble impurities, such 

 as earth, wood, bark, and the like. This milk is best strained 

 into thoroughly well-washed petroleum barrels. As soon as the 



* India-rubber Journal, 2Qth Sept. 1902. 



