204 



THE AFRICAN RUBBER VES^ES 



of fresh rubber ; about a year later it was again tapped 

 and gave 240 cc. of latex, from which 87 grams of fresh 

 rubber were obtained. It was proposed to tap this vine 

 again at the end of another year, but it died during the 

 interval, notwithstanding the fact that the tappings 

 had been very carefully performed. M. Seret concluded 

 from this experience that C. Arnoldiana vines tapped 

 by the native method would be inevitably kiUed, and 

 he suggested that the best method of exploiting these 

 vines would be to tap them at first, and then, after an 

 interval of time to be determmed, to cut them down 

 and extract the whole of the rubber from the stems 

 and root by beating the bark. 



Yields of Rubber (" Root Rubber ") from Rhizomes. 

 LaTidolphia Thollonii. — A series of experiments was con- 

 ducted by the Government of Angola with rhizomes of 

 L. Thollonii collected in the district of Lunda, and the 

 results obtained are summarised in the following table : 



Rhizomes of Landolphia Thollonh 



The rubber obtained in these experiments is stated to 

 have been very much piu-er than that prepared by the 

 natives, who generally only wash the product two or 

 throe times. After the third washing the average yield of 

 rubber from 14 kilograms of rhizomes was 1-593 kilograms, 

 equivalent to 114 per cent., as against the final yield of 

 6-0 to 7-4 per cent, obtained in the experiments. 



