RUBBER PLANTING 203 



When a thickness of about a quarter of an inch of 

 rubber has been obtained, the rolls are slit up so as to 

 form small sheets, which are subsequently washed and 

 dried. 



The method of alternate paring and pricking recom- 

 mended in Hawaii has been found to cause considerable 

 damage to the trees in Ceylon. Paring on the herring- 

 bone system has sometimes been found to give good 

 results if not carried too far. If the paring extends over 

 only an inch of bark, and a space of an inch is then left 

 untapped before the next cut is made, the bark is 

 generally found to heal satisfactorily. Rather wide 

 shallow paring with a small gouge has given good 

 results on Ceylon estates, and has been followed by 

 perfect renewal. In many climates tapping can only 

 take place during dry intervals in the wet season, since 

 the trees drop their leaves during the dry season of the 

 year, and then yield little or no latex. 



Coagulation takes place on the simple addition of 

 water. Very good samples of rubber, closely com- 

 parable with the best Hevea sheet in appearance, have 

 been prepared by diluting the latex with an equal bulk 

 of water and allowing it to stand until coagulation is 

 complete. The further processes involved are precisely 

 similar to those adopted in the preparation of Hevea 

 sheets or biscuits. 



A process which should be rigidly avoided is the 

 mixing of the latices of Manihot and Hevea on estates 

 where both products are cultivated. Such mixture 



