352 



BRIDGMAN. 



The numerical results are shown in Tables XXXII, XXXIII and 



XXXIV and Figures 33, 34 and 35; only the e.m.f. is given for Baker's 

 platinum. For both grades of platinum the e.m.f. is positive and 

 rather large, increasing with pressure and temperature to 21.6 X 10~® 

 volts for the Heraeus platinum, and to 22.2 for Baker's at 12000 kg. 

 and 100°. The similarity of these figures is somewhat unexpected 

 in view of the difference in thermo-electric behavior at atmospheric 

 pressm^e. The Peltier and Thomson heats are quite different, how- 

 ever. The Peltier heat of Heraeus platinum is positive, increasing 



TABLE XXXIV. 



Platinifm (Impure). 



Thermo-electro motive Force, volts X 10^. 



with pressure at constant temperature, but at each constant pressure 

 passing through a maximum with rising temperature. The Peltier 

 heat of Baker's platinum is also positive throughout, is somewhat 

 larger than that of Heraeus platinum, and rises throughout with both 

 temperature and pressure. The Thomson heat of Heraeus platinum 

 changes sign, starting with positive values at low temperatures, and 

 at each constant pressure becoming negative at higher temperatures. 

 The Thomson heat of Baker's platinum rises to its highest positive 

 values at the highest temperature, and for several pressures is negative 

 at the lower end of the temperature range. 



