Knowledge. 



With which is incorporated Hardwickc's Science Gossip, and the Illustrated Scientific News. 



A Monthly Record of Science. 



Conducted by Wilfiud Mark Webb, F.L.S., and E. S. Grew, M.A. 

 M.\KCH, 1912. 



SOME NOTES OX THE CHEMISTRY OE INDL\ 



RUBBER. 



By H. STAXLi:V RKDGKOXE, B.Sc. (Lond.), F.C.S. 

 1. Xatlr.\l Rubber. 



I.NinA-KUBBEK is obtained from a nunibur of trees 

 of which the most important is the jjara rubber 

 tree, Hevea Braziliensis. This tree \ields the finest 

 of all rubber, and, as its 

 name implies, is indi- 

 genous to Brazil. In 

 recent years, however, 

 numerous e.vperiments 

 have been made to culti- 

 vate para rubber trees 

 in other parts of the 

 world, man}- of which 

 have proved very success- 

 ful. Hevea Braziliensis 

 requires for its cultixa- 

 tion a moist, warm 

 climate ; it has been found 

 to thrive particularly well 

 in the Malay Peninsula, 

 as well as in Ceylon. It 

 can also be grown suc- 

 cessfullv in Guiana and 



I'ir,ri;i; ^4. 

 \ Rubber Plantation in Malava 



In Brazil, wild rublier trees are generally tapped 

 by a single incision in the bark. Plantation trees 

 are u?uall\- tapped b\- cutting the bark in one of the 

 three manners shown in 

 I'^igure 86, though other 

 methods of tapping have 

 also been tried. Each 

 dav, or less frequently, a 

 thin shaving of the bark 

 adjacent to each of the 

 ruts is pared away. The 

 milk, or rubber latex, 

 which exudes from the 

 1 iits, runs down the central 

 I hannel, and is collected in 

 a vessel placed to receive 

 It. The rubber has then 

 to be separated from the 

 latex. In the case of 

 Brazilian wild rubber, this 

 is effected by subjecting 

 the latex to the smoke 

 produced by burning cer- 

 ut in the case of plantation 

 enerall)- coagulated b)- the 



certain parts of Africa : 



but the greater portion of Africa, as well as Mexico tain nuts, and so on 



and the West Indies has been found unsuitable rubber the latex is 



for its growth. The output of plantation rubber, addition of dilute acetic acid. Plantation rubber is 



however^ is as yet small compared with that of wild also washed and rolled in special machines, and then 



rubber. Figure 84* is an illustration of a rubber dried (an operation effected in Malaya by smok- 



plantation in Malaya. Figure 85 shows the flower ing the niblieri. before exportation; wild rubber 



of the para rubber tree. has to be treated in this manner after exportation, 



'■ Our heartiest thanks are due to the Malay Slates Development .Agency for photographs reproduced in Figures 84, 85, 87 and 88. 



