B condition que la tension a longueur constante varie lineairement avec l) Voir communication provisoire, Exper. 3, 26 (1947). Fil du pont de Wheatstone: constantan 0 1 mm., 1 m., 0,62 9. RBsistances: constantan $3 0,2 mm., 109 Q. RBsistance d'itquilibre: manganine 0 0.5 mm., 7 Sa env. Resistance variable: 54 9 max. RBsistance variable : 30 9 max. RBsistance constantan: 27 Q env. Ritsistance thermom6trique: platine 0 0,15 mm., 7 52. RBsistance chauffage: constantan 0 0,15 mm., 26,65 Q. Amperemetre MULTAVI I1 (Hurtmann et Braun). AmpkremBtre 0 4 , 0 4 5 ; 0 4 , 1 5 0 A. (Triib-Tauber). Galvanornetre POT (Cambridge Instrument Co.). Galvanornetre K i p p et Zonen, Type Zc (6chelle B 4 m.).

The changes in specific heat of several samples of rubber when stretched were measured. Unvulcanized rubber showed no change in specific heat when it was stretched up to 300 per cent. The specific heat of vulcanized rubber increased very slightly and in proportion to the elongation. With some of the samples, a bend in the curve appeared at about 200 per cent elongation at room temperature, in which case the linear increase in specific heat was about ten times at higher elongations. Supposedly this sudden increase in specific heat is related to the heat of crystallization.

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