86 



tuents contained in the fuel but th^ compound which is formed 

 with sufficient heat in the process of combustion that acts as the 

 real re-agent and coagulates latex ; that volumes or clouds of 

 smoke are not only unnecessary but are* positively harmful ; that 

 a smoke house should be well ventilated and the temperature kept 

 as low as possible; that the furnace or heat should always be 

 generated outside the smoke house; that smoke from a furnace should 

 never go direct on latex or rubber; that fuel (wood or coconut husk) 

 be always dry in view of furnishing comparatively dry smoke; 

 that all smoke be passed through the furnace chimney until the fire 

 is established or burnt through and the temperature very high ; that 

 the fire is well stoked and not choked with too much fuel or allowed 

 to fall too low. 



17. How these various items are arranged in the apparatus I 

 am exhibiting will be explained, but I wish to pause here to emphasise 

 the importance of maintaining a regular supply of smoke from a well 

 consumed fire. Of all the constituents contained in wood-fuel water 

 is the most troublesome. However perfect the combustion water- 

 vapour has to be disposed of, and excess smoke-vapour results in 

 condensation within the house and a steamy atmosphere which is 

 fatal to good coagulation. (The fat and oil ever present on superfi- 

 cially smoked biscuits and sheets is really a deposit of wood naptha- 

 line and other impurities conveyed by excess vapour in smoke due 

 to wet fuel and the smoke passing direct on to the rubber — an error 

 easily avoided). In the process of coagulation it is essential that the 

 evaporation of water within the thin layers of latex shall be commen- 

 surate with the heat supplied (not a high temperature at which 

 caoutchouc perishes), and this cannot occur in an atmosphere sur- 

 charged with steam or vapour, and the result is, the water and 

 caout-chouc coalesce and the resulting rubber is uncured. 



l8- The real problem of the treatment of Hevea latex is one of 

 separation between the water and caoutchouc. With Castilloa and 

 some other latices which contain an acid reaction this can be done 

 by centrifugal motion at high speed, the caoutchouc separates into 

 a mass and can be skinned off. With Hevea latex however, although 

 remarkably flocculent — perhaps more so in Malaya than in South 

 America — such methods are futile. Hevea latex is alkaline to litmus 

 and the process of coagulation, whether with or without a re-agent, 

 is really one of coalescing into an agglutinated mass and the variable 

 water residuum, is I suspect, more the result of pressure than separa- 

 tion or precipitation of caoutchouc. (Under normal conditions Hevea 

 latex coalesces by natural means satisfactorily if placed in a cylinder of 

 which the height is three or four times that of the diameter and the water 

 residuum is about the same as ivhen treated with a re-agent such as acetic 

 acid. In certain phases of the Hevea tree, at the time of this writing, 

 29-1-1912, all the latex in a cylinder 7 ins. by 2% ins. coalesced in fifteen 

 hours without leaving a drop of fluid. Such re-agents as acetic-acid 



* It is paradoxical. Volumes or clouds of smoke imply excess water-vapour. 



