PARA RUBBER. !>7 



to these, other experiments were commenced in order to dete mine 

 the yield of dry rubber obtainable from different sections of the tree 

 abov r e the area usually tapped on estates. 



Rubber-yielding Capacity of Different Areas. 

 Base to 50 feet. 

 Base to 6 to 16 10 to 20 20 to 30 Base to Base to 

 5 & (i ft. feet. feet. feet. 30 feet 50 feet. 



lb. lb. lb. lb. lb. lb. 



Yield of dry rub- 

 ber per 5,000 

 square inches 

 of excised bark 32-55 29-03 22-28 16-45 13-13 5-06 



The above results were obtained at ; Henaratgoda between Septem- 

 ber, 1905, and February, 1906, the system of tapping adopted being 

 the full herring-bone. In most cases the quality of the rubber was 

 good; the quantities are as given in the above synopsis. 



These experiments prove most definitely that the first six feet of 

 bark produce larger proportions of rubber, per unit of excised 

 bark, than any other, and that there is a general decrease in the 

 rubber-yielding capacity of the bark the higher one goes up the stem. 

 In the above results one can discern a fairly regular agreement, and 

 as the figures for parts of the stem as high as fifty feet from the 

 base have not been given before, the conclusions to be drawn are all 

 the more interesting. Other results over larger surfaces agree, 

 more or less, with the above, except that the average yield of 

 rubber per square foot is often higher than that here given for the 

 stem between 6 to 16 feet. 



16 Tappings give 3£ lb. Rubber. 



It is of considerable interest to note that though the rubber- 

 yielding capacity of the cortex of the stem gradually decreases from 

 below upwards, the yield of rubber obtainable from the higher 

 parts of single trees, similar to those at Henaratgoda, is often 

 surprisingly large. The following results show that as much as 

 3£ lb. of rubber may be obtained from one tree in 16 tapping 

 operations. 



