38 Mr. Haldane Gee and Mr. Terry on 



On the Specific Heat of Non-conductors. Part i: 

 Caoutchouc. By W. W. Haldane Gee, B.Sc, 

 F.C.S., and Hubert L. Terry, F.I.C. 



{Received December 2ndy i8go.) 



Comparatively few determinations have been made of 

 the specific heat of non-conductors, and, since a knowledge 

 of this constant has become of some technical importance, 

 we have made a number of experiments with different sub- 

 stances. The present paper will be devoted to Caoutchouc. 

 Fine Para rubber xrr*^ ^^ ^^ ^^^^ thick was generally 

 used, and the following figures represent fairly its composi- 

 tion : — 



Caoutchouc 96*83 



Resin 1*25 



Water 1*77 



Soap, etc 0*15 



100-00 



Since the water is driven off when the rubber is heated 

 to 100° C. the substance actually used contained about 98*5% 

 of caoutchouc and about i'3% of a material whose specific 

 heat would be little different from that of caoutchouc. It 

 may be considered then that we have been dealing with 

 pure caoutchouc of the formula (CioHie)^. For the supply of 

 material and for assistance generally we are much indebted 

 to Messrs. Chas. Macintosh and Co., Limited, of Man- 

 chester. 



As Regnault's method of mixtures was employed, not 

 much description of the process is necessary. At first 

 sight the determination presents the difficulty that the 

 rubber being an exceedingly bad conductor of heat, the 



