606 SCIENCE PROGRESS 



the world's demand was then much greater. Manufacturers 

 would have been chary about risking their money and reputa- 

 tion on an untried raw material. For the planting community, 

 then, it would seem that cultivated rubber has arisen at a most 

 opportune time. Manufacturers are obliged to turn their 

 attention to it, and by doing so must hasten on improvements 

 in its preparation, so that ultimately it will take a place in the 

 rubber market second to none. 



Though the best grades of plantation rubber have almost 

 invariably received a higher price per pound than fine Brazilian 

 Para, yet the buyer is in reality purchasing the cultivated 

 caoutchouc at a rather cheaper rate, for the wild rubber suffers 

 a loss of ten to fifteen per cent, of its weight in washing, whereas 

 the plantation product loses hardly one per cent. Rubber 

 planters will not be content to rest till their article fetches a 

 Relatively higher price than fine Para. 



The influences above mentioned no doubt keep the value 



of ^ plantation rubber intrinsically rather lower than that of 



the Brazilian export; but at the same time there is a general 



impression that the former lacks to some extent the strength 



and> elasticity of the latter. This is at present a much disputed 



po^nt. But taking into account both the general bias of 



manufacturers for the well-tried wild article and also the 



variety in shape and quality of the cultivated rubber now on 



the market, there would seem to be little ground for regarding 



th/e best grades of plantation as inferior to fine hard Para. A 



fair amount of badly prepared and " tacky " rubber from the 



East has reached Mincing Lane from time to time, and this 



must tend to damage the reputation of plantation Para as a 



whole. It may be claimed, however, that previous to the 



arrival of cultivated Hevea rubber from the East, no raw 



caoutchouc so free from impurity and moisture and so pale 



in colour had ever been put on the market. 



The youthfulness of the trees from which the majority of 

 plantation rubber is at present obtained has been blamed for 

 this supposed lack of strength. The tapping of cultivated 

 Heveas is begun when their stems, at a height of three feet 

 from the ground, have attained a girth of about twenty inches. 

 They reach this size under favourable conditions of growth 

 in five or six years from the time of planting. The rubber 

 in the forests of the Amazon is collected from much older 



