12 Schwartz & Kemp, Physical Properties of Rubber. 



In comparing together the calculated and observed 

 curves in Fig. 4, it will be seen that the observed tempera- 

 ture difference is slightly greater than the calculated one 

 for both positive and negative values. The difference 

 between the two curves is, however, slight, particularly for 

 stretching weights of 0'5 lb. and over. In the initial stage, 

 when there is a fall of temperature, the observed curve falls 

 away from the calculated one, but quickly comes into 

 close agreement with it, remaining so throughout the 

 remainder of the range. The heat radiated away or 

 otherwise lost before the galvanometer reached its 

 maximum deflection does not seem to have had any 

 appreciable effect. 





^ 



Fig. 5- 

 Spread Rubber Tape. Rested for 3 Years. Stretched at o°C. 



Fig'.^ shows the results obtained by testing in a similar 

 manner a piece of spread rubber tape which had been 

 rested for three years. The effect of age is indicated by 



