January, 1910.J 



5 



Saps and Exudations. 



cut up, pressed and heated, could be 

 moulded into almost any shape, and 

 when, in 1874, the method of vulcanising 

 rubber by heating and treating it with 

 sulphur was discovered. 



From that date the imports of rubber 

 into this country have increased enor- 

 mously, and on the whole steadily, from 

 about 150,000 cwts. in 1874 to 194,000 in 

 1886, 430,000 in 1896, and 600,000 in 1906. 



It is a remarkable fact that, of the 

 rubber consumed throughout the world 

 in 1906, almost one-half was derived from 

 rubber imported into this country. It 

 is also note worthy that more than half 

 of the rubber used is Para rubber, that 

 is, material derived from the latex of 

 species of hevea, and chiefly from that 

 of H. brasiliensis. Now that so much 

 capital and industry are being put into 

 the cultivation of rubber-producing 

 trees, it is interesting to note the 

 attempts to produce rubber syntheti- 

 cally. Already various " rubber substi- 

 tutes" manufactured from the seeds of 

 Poppy, Rape, Flax, &c,, are in use for 

 mixing with crude rubber for special 

 manufactures ; but, so far, all attempts 

 at the artificial manufacture of the 

 genuine article have failed. He would 

 be a rash man, however, and one ignorant 

 of the wonderful fertility of resource of 

 organic chemistry who predicts that 

 synthetic rubber is an impossibility. 

 The main reason why its manufacture 

 is likely to prove difficult lies in the 

 fact that rubber is not a single sub- 

 stance, but a mixture of complex com- 

 pounds such as proteins, resins and 

 caoutchouc. The significance to the 

 tree of the latex from which crude rub- 

 ber is prepared is doubtful. Most autho- 

 rities regard it as a waste product of 

 vegetable metabolism ; but the author, 

 having regard to its widespread distri- 

 bution of plants, is inclined to think 

 that it plays some part, albeit a small 

 part, in the economy of plants, Mr. 

 Johnson has given a most comprehensive 

 account of the various processes con- 

 nected with cultivation ami preparation 

 of rubber, and brings out incidentally 

 the prominent part — on which we have 

 more than once insisted in these pages — 

 played by British Colonies, particularly 

 by Ceylon and Malaya, in introducing 

 rubber plants for cultivation. 



From his estimates of cost it would 

 appear that the cultivation of rubber is 

 an extraordinarily profitable industry; 

 but as to whether at the present prices 

 of rubber shares it is a profitable invest- 

 ment the author is properly silent. 



In conclusion, we would say that Mr, 

 Johnson has written an admirable book, 

 interesting not only to the expert but 



also to the layman who takes an intelli* 

 gent interest in the progress of agricul- 

 ture and of commerce. 



A DEVICE FOR MEASURING THE 

 GIRTH OF RUBBER TREES AND 

 TAKING A CENSUS. 



By P. J. Burgess. 



(From the India Rubber Journal, Vol. 



XXXVIII., No. 8, October 18th, 1909.) 



With the large number of young 

 rubber plantations now approaching the 

 tapping stage, positive information of 

 the number of trees classified according 

 to their girths is necessary both on the 

 plantation and in the board room. To 

 obtain this information by measuring 

 with a tape and writing down the result, 

 is slow and expensive in labour, and, in 

 addition, requires skill labour, in that 

 the coolies must be able to read figures 

 and write them correctly, and there is a 

 lot of further clerical labour wanted for 

 sorting out the mass of results obtained. 



The device I am going to describe was 

 made to overcome these difficulties, and 

 it was entirely a success in practice. 

 The apparatus wanted can be made by 

 any one ; it is figured below. Take a rod 

 3 ft. 6 in. long, and 6 in. from the end fix 

 a leather strap so that three or four 

 inches project, and into this projecting 

 end fix a drawing pin. 



The strap should be about an inch 

 wide and not too thick. On the surface 

 of the strap fixed to the rod, paste a 

 strip of white paper and the instrument 

 is ready to use. 



B 



A B Rod 3 feet 6 inches long. 

 D E Strap. 



F Point of drawing pin. 



C B is 3 feet in length. 



The surface of the strap shewn 

 is applied to the tree. 



The strip of paper is pasted 

 to the other surface of the 

 strap. 



To use it, stand the rod upright against 

 the tree, wrap the strap round the tree, 

 the paper-coated side will be away from 



