Rubber 



285- 



Here it coagulated, and as a result a cake or " biscuit " of rubber about i in. thick was obtained, 

 which was thoroughly dried by rolling arid other means. (See illustration on p. 290.) These 

 experiments resulted in putting on the marketthe now well-known " Para -biscuks," which have 

 earned a high reputation for their purity. They entail, however, a large amount of hancj labour, 

 and are accordingly being replaced at the present time by other and more expeditious methods. 

 Before we refer to those it will be convenient to note that much experimental work has been 

 and is being done in methods of tapping. The little cups, each under a separate cut, also- 

 demand a lot of labour, and it is found advantageous to collect the latex in as few cups as possible, 

 some going so far as to suggest catching the yield of more than one tree in a single receptacle 

 by means of suitable guiding channels. The " herring-bone " method ismow largely adopted. 

 It consists of a vertical cut several feet' long, with branch cuts leaving it at an angle of about 

 45° alternately on either side. The branch cuts point upwards; and. the latex from them runs 

 into the central vertical cut at the lower end of which the cup is placed. In tne half 

 herring-bone branch cuts are made only on one side of the vertical cut. 



Still more recent is 

 the spiral mode of 

 tapping. A series of 

 cuts running spirally 

 half-way round the 

 tree is made from a 

 height of six feet or so 

 to the base. This 

 method appears to be 

 very successful. It has 

 the advantage that as 

 the wounds in the 

 bark heal, the old 

 places can be readily 

 tapped again, and in 

 the Para rubber the 

 yield from over the 

 same area increases 

 rapidly at successive 

 tappings, an interest- 

 ing and important 

 phenomenon spoken 

 of generally as 

 " wound-response." 



The yields from 

 some of the spiral 

 tappings in Ceylon 

 have been very high, 

 as much as 25 lb. of 

 rubber from a single 

 tree in a year, without 

 the tree showing any 

 ill effects. Such a 

 yield is, no doubt, ex- 

 ceptional, but for trees 

 between five and ten 

 years old, grown under 



By permission of Messrs. Maclaren, Shoe Lane' 



GROUP OF HEVEA BRASILIENSIS 



