

INDIA-RUBBER 

 SOURCES BOTANICAL I .V CAOUTCHOUC 



tannin, to which collectively he gave the name of viiiarln, a word derived from the 

 Tamil namo of the plant. [Of. Christy, New. G'omm. /'/.. 1*78-88, 68-' 

 macog. Ind., ii., 107-10 ; Waring, Baz. Mtd. of Ind.. 1897, 75- il ; Pharm. Journ., 

 July 1, l.v.nt. Uiii , ltt~7; Dutt, Mat. Med. Hind., 1900, 17 ; Jtept. Cent. India. 

 Drug* Comm., 1901, i., 14, 02, 146, 179.] 



I 



INDIA-RUBBER, CAOUTCHOUC OR GUM ELASTIC. D.E.P., 



Caoutchouc, like gutta-percha, is a vegetable inspissated milk or latex, iv.,337-82. 



In both cases the substance consists of a hydrocarbon, forming corpuscle- In ?l* 



like bodies floating in a fluid. Gutta-percha becomes soft and plastic in T 



hot water and may be moulded into any desired shape, which it preserves 



on cooling. Caoutchouc, on the other hand, is not softened by heat, is 



impervious to water, alcohol and most acids, etc., and retains its elasticity 



for a considerable period. Gutta-percha is chiefly obtained from trees 



that belong to the SAPOTACE.S, while caoutchouc is derived from certain 



plants which have been placed in three widely different natural orders, chief source* 



These are Fit nt inn in. ll<inroriti<t, Lfiinfofjt/iia and H'ilt<m<//ihri<i 



of APOCYNACE.E ; ('(istil/otr and Firm* of URTICACE.S, and llcrt-a and 



Man Hint of EupHORBiACE.fi. The plants that afford gutta-percha and 



india-rubber thus manifest no definite botanical affinity, except that they 



are mostly natives of tropical countries. In the plant tissue caoutchouc 



circulates within certain anastomosing vessels which are distributed 



throughout the middle, or more rarely the inner layer of bark. [C/. 



Lecomte, Journ. d'Agri. Trap., 1903, xvii., 375.] A far larger number of 



plants possess milk (and even a caoutchouc-yielding latex) than those 



generally viewed as the sources of india-rubber. The term caoutchouc Caoutchouc. 



is sometimes used synonymously for india-rubber, but it more correctly 



denotes the pure hydrocarbon isolated from the other materials with 



which it forms the impure rubber of commerce. Caoutchouc is highly 



elastic, lighter than water, has neither taste nor smell, is fusible at about 



248 F. and inflammable at higher temperatures. 



Methods of Agglutination. When the bark of plants containing rubber Tapping, 

 is cut, the milk exudes, and in time hardens on exposure to the air. This 

 agglutination may be hastened by adding salt water, alum or acetic acid 

 to the milk ; but these, more especially salt, increase one of its defects, \J M of g^t, etc. 

 viz. the hygroscopic property by which it becomes moist and sticky, and 

 in consequence they injure it commercially. A favourite but wasteful 

 method is to allow the milk to flow into holes in the ground and to be 

 left there till the water, etc., has drained off. Boiling the milk is the Boiling, 

 system followed in Lagos, while in the Amazon valley the smoke of a smoking, 

 smouldering fire, combined with moderate heat, is the system almost 

 universally pursued with Para rubber. In a few cases the milk is simply 

 allowed to dry as it trickles down the stem. This gives the SCRAP RUBBER scrap Rubber, 

 of Ceara and a good deal of that of Assam and Penang. The alum (or Alum. 

 Penang) process was recognised as being useful for Assam, where the 

 humid atmosphere operates against the drying of the rubber. Dr. C. 0. 

 Weber, in a series of articles contributed to The India-rubber and Gutta- Weber's 

 percha Trades Journal in 1902, also 1904, has stated the facts regarding Method, 

 coagulation briefly as follows : 



1. That the so-called coagulation of rubber by acids or alkalis is 



647 



