32 THE PRINCIPAL RUBBER- YIELDING PLANTS 



The rubber-yielding species of Manihot are described 

 in chap. x. p. 137. 



3. Sapmm spp. 



A number of trees belonging to the genus Sapium 

 occur throughout the northern part of South America, 

 being found in Colombia, Venezuela, British Guiana, 

 Ecuador, Peru, and the Amazon valley. Rubber of good 

 quality is loiown to be furnished by some of these trees, 

 but the botanical identity of the rubber-yielding species 

 is not in all cases fully established. It appears certain 

 that the " caucho bianco " rubber from Colombia is 

 derived from a species of Sapium which Jumelle believes 

 to be Sapimn utile, Preuss. 



In Brazil only one species of Sapium, *S^. Taburu, Ule, 

 is known to yield good rubber. This tree is very common 

 in certain districts on the alluvial lands along the main 

 river and its tributaries. The latex is generally mixed 

 with that of Hevea hrasiliensis, but in those districts 

 where the latter species does not occur, the rubber of 

 8. Taburu is prepared by allowing the latex to coagulate 

 on the tree and then collecting it in ball form. 



Several species of Sapium occur in British Guiana, and 

 two of these, Sapium Jenmani, Hemsl., and Sapium 

 cladogyne, Hutchinson, yield rubber of good quality. 

 Authentic specimens of the rubber obtained from forest 

 trees of Sapium Jenmani were found on examination at 

 the Imperial Institute to be very little inferior in com- 

 position and value to the best Para rubber. The follow- 

 ing analysis of a sample specially prepared in biscuit 

 form by Mr. C. Wilgress Anderson, of the Forestry De- 

 partment, may be quoted : 



Moisture 



Caoutchouc 



Resin 



Protein 



Ash 



This sample was valued at 45. M. per lb. in London 

 with fine hard Para at 4.s. Z^d. per lb., and plantation 

 Para biscuits at 45. 4fZ. to 45. \\d. per lb. 



Sapium Jenmani has been planted on a small scale in 



