RUBBER 663 



have a wooden ceiling beneath the iron. Usually the 

 bottom floor is used as a packing room, and frequently the 

 lower grade crepes are suspended from the open boards 

 of the ceiling of this bottom story. In no case should a 

 drying room be immediately over the washing factory, and 

 preferably not running along the length of the factory 

 in the case of a one-story combined factory and drying 

 shed, unless the floor of the former is so constructed 

 that no water can possibly drain towards the drying 

 room, since such drying rooms would be continually 

 damp, and spot diseases due to the growth of fungi and 

 bacteria would be prevalent. A drying room should be 

 preferably quite a distinct building; no sunlight should 

 be allowed to come into direct contact with the rubber, 

 otherwise tackiness occurs, so that all windows should 

 be protected with red or yellow cloth, which allows the 

 passage of air, but shuts out the direct rays of the sun. 



In my opinion, drying rooms and smoke-rooms should 

 be divided into compartments, since the introduction of 

 wet rubber into a room containing partially dried rubber 

 retards the drying of the latter considerably. 



Hot-air Drying. Three systems are in use in the 

 Federated Malay States : (a) Chambers, such as the 

 Chula and Colombo driers, in which the hot fumes of 

 combustion of ordinary wood or other fuel are passed 

 through pipes leading through the chambers in which the 

 rubber is hung or spread on racks; (b) large steam pipes 

 through which steam at ordinary pressure is passed, and 

 over which the air passes before reaching the rubber; 

 (c) narrow steam coils through which steam under pres- 

 sure of about 60 Ib. per square inch is passed, the air 

 entering below the pipes and being heated by them before 

 passing through the rubber. In each case an exhaust 

 fan or a forcing fan is used to circulate the air more 

 rapidly. The two latter processes are at present in use 

 by the Department of Agriculture, Federated Malay 

 States. 



Vacuum Drying. At present this process is only used 

 on one or two estates in Malaya, one being an estate 

 on which vacuum-dried crepe is subsequently blocked. 



The chief drawback to the use of vacuum driers or 



