MANY OR SPECIAL PURPOSES 363 



is all evaporated, that he sells, as "gutta." We 

 call this solid substance "gutta percha." 



The peculiar property that sets gutta percha 

 apart from rubber is its softening in warm water, 

 and becoming rigid again when cooled. It is 

 inelastic. Otherwise it is like rubber. 



Gutta percha is used chiefly to insulate wires in 

 electrical apparatus. The laying of the Atlantic 

 cable created a considerable demand for it. 

 Dentists and artists prefer it to other substances 

 for taking impressions. It is one of the materials 

 used for the handles of surgical instruments, and 

 similar articles. 



The nearest natural substitute for genuine 

 gutta percha is made from the juice of the bullet 

 tree, a near relative of the true getah taban. It 

 grows in Trinidad and South America, and its 

 juice, while containing gutta, is about half resin, 

 which is a great nuisance. The product is called 

 Balata, or Surinam gutta percha. 



"Pontianac," made from the juice of certain 

 East Indian trees, is an inferior waterproofing 

 material, cheap in price, for, with a small propor- 

 tion of gutta-like substance, it contains a high 

 percentage of resin and other elements. 



The five species of true gutta percha trees 

 belong to the genus Dichopsis, and grow only on 



