

GUTTAPERCHA. 29 



its shape and is sufficiently hard for use at all temperatures 

 below about 90° Fahrenheit. In its liability to stiffen in cold, 

 Gutta Percha resembles South American caoutchouc. Gutta 

 Percha also resembles South American caoutchouc in its resist- 

 ance to injury by friction and percussion. It becomes elastic 

 at certain temperatures. Its chemical composition is the same 

 as that of South American caoutchouc, namely, 87 parts car- 

 bon and 13 hydrogen. It possesses similar powers of chemical 

 combination with the South American gum. It is susceptible 

 of the change called vulcanization by being suitably prepared 

 and being exposed with sulphur to a high degree of artificial 

 heat; and in some forms of vulcanization, and in some com- 

 binations, particularly in that called the hard compound, it may 

 be worked with equal advantage with South American caout- 

 chouc. It is' to be remembered that we receive the South 

 American gum after its having been once manufactured by the 

 Indians — while we receive Gutta Percha not in a manufactured 

 state, though it is frequently and generally, if not always, mixed 

 with inferior gums or substances at the place of production, for 

 the purpose of adulteration and greater profit. It is probable 

 that the South American caoutchouc and Gutta Percha, when 

 both perfectly pure and unmanufactured, and of the same age, 

 resemble each other much more closely in their properties and 

 powers than we are at present able to state with certainty. 



Comparison of Gutta Percha and India Rubber, by Charles 

 C. Page, Professor of Chemistry, National Medical College, 

 Washington, D. C. From " Silliman's American Journal," vol. 

 4, second series, page 341. 



Professor Page says : — " It is somewhat remarkable that the 

 interesting substance, Gutta Percha, appears very much like the 

 India rubber when rendered inelastic by exposure to cold. 

 This valuable modification of caoutchouc (Gutta Percha) gives, 

 according to Dr. Maclagan, by ultimate analysis, carbon 86t^/o, 

 hydrogen 12tVo ; and caoutchouc, according to Faraday, gives 

 carbon 87tIt, and hydrogen I2Tfo-. The Gutta Percha yields 



s-g^^ 



