I'~EBKUAKV 2, 1 9O5] 



NA TURE 



321 



PARA RUBBER.' 



IN recent years the cultivation of rubber-yielding 

 trees has attracted an increasing amount of 

 notice. About 12,000 acres in Ceylon, and in the 

 Malay Peninsula a still larger area, have been stocked 

 with the Para rubber tree, Hcvea brasiliensis, and 

 other species of Hevea. The cultivation has also 

 been successful in India and South America, and ex- 

 perimental plots are being tested in Uganda and 

 the Gold Coast Colony. 



In tropical Africa there are thousands of square 

 miles of land suitable for growing 

 the Para tree. But whilst the 

 demand for rubber has been in- 

 creasing with the development of 

 the electrical and motor industries, 

 the number of forest trees yielding 

 the substance has been diminish- 

 ing, year by year, as a consequence 

 of the faulty methods of " tapping " 

 employed by the natives. Hence a 

 stimulus has been given to the pro- 

 duction of rubber by cultivation ; 

 and with a view of fostering the 

 industry in West Africa, Mr. John- 

 son was commissioned by Govern- 

 ment in 1902 to visit Ceylon and 

 study the methods employed there 

 in the management of the planta- 

 tions and the preparation of the 

 rubber. He now gives, for the 

 benefit of persons taking up the 

 cultivation, some of the results of 

 the visit in the form of such practi- 

 cal advice as would be likely to 

 assist them in their undertaking. 



The rubber trees are raised from 

 the seeds, which may be obtained 

 from Ceylon or the Straits Settle- 

 ments at a cost of about 6s. Sd. per 

 thousand. When the tree has 

 attained a girth of twenty to 

 twenty-four inches, the latex can 

 safely be tapped ; this may be in 

 about five to seven vears from the 

 date of planting. The yield varies 

 greatly, depending on the soil, the 

 age of the tree, and the method of 

 tapping. At present no really 

 satisfactory data are available ; 

 but from such statistics as are given 

 it -would seem that about i lb. to 

 3 lb. of dry rubber per annum may 

 be the average product of each tree. 

 In addition, the seeds yield a drying 

 oil somewhat resembling that ob- 

 tained from linseed. As regards 

 the latex-bearing " life " of the 

 trees, it is stated, on the authority 

 of the director of the Botanic 

 Gardens, Straits Settlements, that 

 trees are known to have been 

 tapped, off and on, during fifty 



years, and to be still yielding a _ _ _, , 



plentiful supply of latex." 



The rubber-substance is contained in the latex of 

 the plant in the form of minute globules, much as 

 butter-fat exists in cow's milk. These globules can 

 be made to coalesce by centrifugal action, just as 

 cream is formed from milk in an ordinary separator ; 

 but the product thus obtained does not, apparently. 



compare favourably with the rubber given by the 

 older methods of separation. These consist in 

 toagulating the late.x, either by simple exposure to 

 the air or by the addition of an acid or a salt ; the 

 resulting coagulum is washed and rolled to free it 

 from moisture and nitrogenous matters, and then 

 dried by gently heating. The particular process 

 suggested by the author is that of spontaneous 

 coagulation of the latex in shallow saucers, followed, 

 after washing and rolling, by exposure to the smoke 

 <.if a wood fire as an antiseptic treatment. The price 



One of the Parent Tre 

 IS, Henaratgoda, Ceyli 



(Fn 



1 "The Cultiv 

 Johnson. Pp. 

 Price 7i. 6ef. net. 



lion and Preparation of Para Rubber.' 

 ;i+gg. (London; Crosby Lockwood ai 



By W. H. 



tJon, 1904,) 



NO. 1840, VOL 71] 



obtained depends largely upon the care exercised in 

 the preparation. For example, Congo rubbers, which 

 some time ago realised only is. to is. 6<i. a pound, 

 now often fetch 45. in consequence of being more 

 carefully prepared. As showing what can be done 

 in this direction, it is interesting to note that Ceylon 

 Para rubber has recently commanded the " record " 

 price of 55. 6d. per pound. 



The appurtenances required are of the simplest, 



