RUBBER AND ITS COMPOSITION. 



Rubber is a product obtained from the milky 

 juice of various trees and vines peculiar to the 

 Tropics. 



It is composed of minute globules suspended 

 in a liquid in the form of an emulsion, contain- 

 ing albuminoids and a resinous substance. 

 These turn black when exposed to the air and 

 light. 



In this process the globules of rubber come 

 together quickly, and gain the elasticity which 

 constitutes its value. 



After coagulation takes place, the albumin- 

 oids and resin remain in the rubber produced, 

 while the liquor is evaporated. 



This product is sometimes called caout- 

 chouc, also gum elastic and India rubber. 



WHERE IT COMES FROM. 



India rubber, or caoutchouc, is obtained 

 from several varieties of trees, shrubs and vines, 

 nearly all of which are indigenous to the 

 Tropics. South America, Central America, 

 India and Africa each furnish large quantities, 

 the gum produced being all rubber, differing 

 somewhat in its character, due largely to the 

 various methods of gathering and coagulation. 



Para rubber (Hevea brasiliensis). What is 

 known as the Para rubber of commerce is ob- 

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