Manchester Memoirs, Vol. Iv. (191 1), No. \'i. 



XII. Some Physical Properties of Rubber 



By Professor ALFRED Schwartz 



AND 



Philip Kemp, M.Sc.Tech. 



Read Novenibei- 3gt}u igio. Received for publication, Fehi-nary 21st, igii. 



Introduction. 



The demand for rubber for industrial purposes has 

 led to an enormous increase in the supply of this material 

 within the last {^^ years. The applications of rubber in 

 the arts are based on some one or other of its many 

 physical properties, and it is now beginning to be recog- 

 nised that more reliance can be placed in the indications 

 given by physical tests on rubber as to its suitability for 

 mechanical or electrical work than in those yielded by 

 chemical analysis. 



The true function of the physical tests in this con- 

 nection would appear to be to deal with effects, while that 

 of the chemical tests would be to determine the causes 

 which produce these effects. 



Our knowledge of the physical properties of this 

 important material has not kept pace with its output for 

 industrial purposes, and we are indebted mainly to two 

 early members of this society — John Gough and J. P. 

 Joule — for much of our knowledge of its curious pro- 

 perties. 



Experimenting in 1802 John Gough^ found that: — 

 " By placing a slip of rubber in slight contact with the 



1 Me?n. Lit. ^ Phil. Sac. Manchester, 2nd Series, vol, i. 

 May 2nd, igii. 



