GUTTA-PERCHA. 733 



been very wasteful hitherto. The tree is felled and the bark 

 stripped or rings cut in it at intervals of a foot. The sap 

 oozing out is collected, put in a pot and boiled with a little 

 water, it is then run into moulds. The trees used are 30 to 

 35 years old, each tree yielding 2 to 3 Ibs of gutta-percha. 

 French exports say that it can be obtained from the leaves, 

 which, H. C. Hill (Report on Forest administration of the 

 Federated Malay States, 1900) says yield the best gutta-percha, 

 valued at 15s. a Ib. Hill recommends the planting of the 

 above-mentioned species, with Fa<jrae<i frayrans and Afzelia 

 palembartica to act as nurses, and advises experiments being 

 made to ascertain the most economical method of obtaining 

 gutta-percha with the least damage to the crop of trees. 



Gutta-percha differs from caoutchouc chiefly in its plasticity 

 under heat.* Thus, if a piece be put in water, that is 

 heated gradually, it becomes more and more plastic, until at 

 190 F. it can be drawn out into forms which it retains on 

 cooling. It is used specially in submarine cable-factories 

 and also for making golf-balls and for other purposes. 



In 1899 the imports of gutta-percha were as follows : 



Great Britain . .... 4531 tons. 

 Rest of Europe .... 2494 

 United States 197 



Terry says that since the completion of the all-British 

 Pacific cable, exports and prices have materially declined. 



Balata occurs as a latex in the bark of several sapotaceous 

 trees, of which Mimusops balata is the principle producer. 

 The tree is found in many equatorial regions, but chiefly in 

 Venezuela, the Guianas and the W. Indies. Terry states, that 

 unfortunately it is lumped together with gutta-percha in our 

 trade returns, but as it is used largely in the manufacture of 

 belts for driving machinery and is much more resistent to 

 atmospheric oxidation and in toughness than gutta-percha, its 

 production should be an important industry ; it is used very 

 largely in beet sugar-factories for machinery belting, as it 

 withstand the chemical solutions met with. About 1,000 

 tons annually are imported into Europe. Tr.] 



* Terry, <>j>. r/7. 



