. Memoirs and proceedings of the Manchester Literary & Philosophical Society . alvanometer,the movement of which was aperiodic, due to the gradualrise of temperature experienced by the were attached, by means of a cord, to the lowerend of the rubber specimen, and the resulting deflection ofthe galvanometer noted, the specimen being brought backto a condition of no load between each reading. Frequentlya minute or so would elapse before the maximum deflectionwas registered, so that, except in the cases of the smallerdifferences of temperature, some heat would be lost by
. Memoirs and proceedings of the Manchester Literary & Philosophical Society . alvanometer,the movement of which was aperiodic, due to the gradualrise of temperature experienced by the were attached, by means of a cord, to the lowerend of the rubber specimen, and the resulting deflection ofthe galvanometer noted, the specimen being brought backto a condition of no load between each reading. Frequentlya minute or so would elapse before the maximum deflectionwas registered, so that, except in the cases of the smallerdifferences of temperature, some heat would be lost by MancJicstcr Memoirs, Vol. Iv. (1911), No. 1*^. radiation and other causes before the galvanometer cameto rest. It was found that a deflection of i mm. on thegalvanometer scale was produced by a potential differenceof 0*0241 micro-volts at its terminals. The thermo-electric value of copper and eureka being taken as 40micro-volts per degree Centigrade, it was found thatI mm. deflection corresponds to ooooiQiC. The curve in Fig. 4 is a typical example of the thermal + ooz fj I. - 00^ O OS /o /S Fig. 4. effects obtained by the authors, the neutral point, whereneither heating nor cooling takes place, occurring at atension of 19 lbs. per square inch. The other curve in thesame figure is obtained by calculations based on Chauveaushypothesis. The calculations are based upon a lengthof I cm. Initial volume of i cm. length =0*4 Specific Heat =04i5 (Joule). Specific Gravity =0965 (Joule). lo Schwartz & Kemp, PhyskaL Properties of Rubber. Ergs required to raise i cm. length through i° 0-415 X 0-965 X 0-4x4-2 X 10^= 6-Jiy. 10. It is here assumed that the specific heat andspecific gravity remain unchanged on the application oftension. The work done in extension is equal to i\We\where {W) is the tension applied gradually, and {e) isthe elongation. This is equal to the work done in dis-placing the molecules relatively to one another, and is acause of heating. The work done in enlargin
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