325 



It appears that during the past few years the difference in value 

 between the washed wild para washed Plantation rubber has in- 

 creased from I franc to 1. 50 per kilo in 1906, to 2.91 and 7 francs a 

 kilo in about a year. 



It has been suggested that this diminution in value has been 

 caused by the great over tapping due to the demand for rubber on 

 account of the high price it reached during the past few years. Other 

 people attribute it to the age of the trees tapped, and those who in- 

 cline to this opinion seem to have chiefly studied the amount of 

 resins soluble in Acetone which may make the difference in value. 



H. Wright in his ** Hevea braziliensis " p. 205, says the resins or 

 oils vary from I to 4 per cent according to the age of the trees. 



M. Kelway Bamber in the report of the Committee of Agri- 

 cultural Experiments in Ceylon gives : — 



Moisture 



2 years 



4 



6 



8 



10-12 



30 



.70 



.65 



.55 



.85 



.20 



.50 



Ash 



.50 



.30 



.40 



.14 



.22 



.25 



Resin soluble) 



3.60 



2.72 



2.75 



2.66 



2.26 



2.32 



in acetones. ) 







Proteins 



4.00 



1-75 





1.75 



2.97 



3.69 



Rubber 



91.20 



94.58 



9479 



94-60 



94-35 



93-24. 



In other rubbers something of the same kind has been shown. 

 C. O. Weber showed that in Castilloa passing upward from the trunk 

 to the leaves the amount of resin in the latex rose gradually from 

 2.61 to 750 per cent. And M. Vernet has shown that the younger the 

 branches of Ficus elastica are, the more sticky is the rubber, and that 

 in Landolphia and other Apocynaceae the young parts of the plant give 

 only a sticky substance while the adult parts of the same part give a 

 latex containing a strong rubber. 



Many planters whom M. Vernet had consulted affirmed that they 

 never found that the age of the trees made any difference to the sale 

 price of the rubber on the market, but this is no criterion as prices 

 were given for appearance as much as for real commercial value. 

 Caoutchouc from trees of various ages were sent from the Botanic 

 Gardens, Singapore, to America and England for analysis and the 

 verdict was that there was no difference. M. Vernet sent to the firm 

 of Michelin, in France, latex from trees of different ages in the Botanic 

 Gardens of Singapore and the result of analysis he gives as below. 



5 years 10 years 20-30 years. 



Ash 0.03 per cent 2 per cent .25 per cent. 



Resin from 1 _ _ _ _ 



the dry rubber./ ^'^^ " " ^'^^ " " ^'47 » 



