PARA RUBBER. lJi 



desired temperature lias been reached the pan is filled with latex 

 from the feeder, and the small toller is turned by hand or power. 



" The surface of the small roller being in contact with the sur- 

 face of the large drum turns it. and at the same time spreads a thin 

 film of latex on its surface. The action of the heat and fumes on 

 the thin film of latex coagulates and dries it. ( 'ontinuing the process 

 the latex is spread Him by film, coagulated, and dried until a thick 

 deposit of rubber surrounds the large dram. The damper on the 

 centre baffle plate is then shut and the door in the smoke box opened. 

 The rubber on the drum is slit across with a knife and unrolled in a 

 large sheet, which can be cut to any size for packing. 



" The antiseptic qualities of the fumes tend to preserve the rubber, 

 and the sheets arc treated through and through." 



In communication with Mr. Dickson I learned that in his 

 machine there are several doors, which can be opened to let cool air 

 in or regulate the temperature — a most important and essential 

 feature when (hying rubber with hot air or fumes. The illustration 

 on Plate 25, Scries A. snows the general plan of the apparatus. 



Another apparatus has been devised in Ceylon to dry the 

 rubber quickly and to coat the freshly coagulated and rolled 

 product with creosote, but has not yet been made public. 



Use of Calcium Chloride. 



Mr. Burgess, in his lecture already referred to, stated that it is 

 possible to dry rubber quite well and satisfactorily without any arti- 

 ficial heat, by the use of some agent that will dry the air. For this 

 purpose he recommended calcium chloride. This substance is made 

 commercially on a large scale : it is comparatively cheap and very 

 effective as a drying agent. The material as bought is in white 

 granular lumps which, when placed in the open air, absorb moisture 

 from it, and the calcium chloride becomes moist and eventually 

 absorbs so much water that a syrupy liquid results. The great 

 merit of this substance lies in the fact that it can be recovered from 

 the wet state by simply heating and thereby driving off the 

 moisture. A simple form of rubber-drying shed adopted for use 

 with calcium chloride could easily be made with shelves to hold 

 iron pans, in which the calcium chloride could be placed and freely 

 exposed to the air in the chamber. As the calcium chloride 

 absorbs the moisture and becomes sloppy, the pans should be 

 removed and the water driven off over a brisk fire, stirring the mass 

 meanwhile. When quite dry and porous a^ain the pans should be 

 returned to the rubber-drying chamber to do their work again. In 

 this way there would be little or no loss of substance, and the air 

 inside the chamber being constantly dry, mould would be absolutely 

 prevented, and the rubber would dry in half the time. The pans, 

 if used inside the rubber shed should be placed above the rubber. 



" A still more efficient system would be to devise a circulation of 

 dry air in the chamber, and if this system were adopted it would be 

 best to dry the air before blowing it with fans into the chamber. 



(16) 



