214 



" Samples from the same origin, but previously dissolved in 

 carbon bisulphide and filtered through a cotton filter, gave the 

 following result : 



Caoutchouc 

 Resin 



• • • ••■ • « • ■•• • • 



Average Composition 



per cent. 



92-640 



• • • •■• ••• ••• - • • ••• 



3-570 



Substances soluble in alcohol at boiling point 2*825 



Substances soluble in water .♦. 0-965 



u The other method is still worse. It is as follows : the roots are 

 boiled and then pounded in a mortar. The mass thus obtained is 

 washed out with cold water to eliminate the pulp, and then put in 

 boiling water in order to become workable. Of this mass (which, 

 of course, is still contaminated with a great percentage of pounded 

 vegetable matter) they make mutares analogous to those described 

 above. 



" This process is — as may well be imagined — much worse than 



Lat the rubber remains contaminated with 

 a great deal of organic matter which easily sets up fermentation 

 and deteriorates the rubber." 



Prof. Geraldes also touches the very important point of the rate 

 of growth of the ' Ecanda ' tubers. On p. 148 he describes the 

 plants as " biennial (?)," and adds in a foot-note : ** one-year old 

 roots which I examined (in the fruiting state) had a diameter of 

 8-10 cm. (about 3-4 in.), and weighed 200-300 grammes 

 (7-10^ oz.) ; the larger tubers which I saw and which were at 

 least two years old measured 12-14 cm. (4|-5^ in.) across and 

 weighed 400-600 grammes " (14-21 oz.). There is no evidence 



^rot. Geraldes raised plants from 

 mentioned the fact had he> rlnrw 



age of the tubers measured and weighed rests, apparently, entirely 

 on assumption. A priori it appears very improbable that the 

 ' Ecsinda ' plant should flower in the first year of its growth, or 

 i hat its tubers should attain the dimensions given above in so 

 ihort a time. In any case this point demands close examination, 

 as the productiveness of an ' Ecanda ' plantation would to a great 

 extent depend on the rate of growth. Prof. Geraldes' calculations 

 of the yield of ' Ecanda ' plantations have therefore to be taken 

 cum grano salis, and appear in any case far too optimistic. This 

 is what he says on p. 168 : 



" 1. If roots one year old are worked, one hectare (nearly 2| acres) 

 might yield 111,111 'Ecanda' plants, weighing 27,778 kilos 

 (about 27 tons), and producing 125 kilos (nearly fy cwt.) of 

 caoutchouc (chemically pure and dry), or a gross return of 

 312 dols. 500 reis per annum. 



Q .," ^ lf ° nly two y ear ro °ts are worked, a hectare might yield 

 M,.> : " Ecandas,' weighing 41,666 kilos (about 41 tons), and pro- 

 ducing about 200 kilos of caoutchouc (chemically pure and dry), 

 or a gross return of 520 dols. 8:50 reis per annum." 



At present there are about 20 species of Raphionacme known, 

 nearly all of them natives of Tropical Africa south of the equator. 



