THERMO-ELECTRIC QUALITY UNDER PRESSURE. 



363 



higher pressures. The Peltier heat is positive; in general it increases 

 with rising pressure and temperature, but at the middle of the range 

 it passes through a flat minimum with rising temperature. The 

 Thomson heat shows complicated behavior; at 2000 kg. it is through- 

 out zero, at 4000 it is negative, and at higher pressures it is initially 

 negative, rising to positive values. 



Wagner found at 300 kg. between 0° and 100° the value 707 X lO'^^ 



TABLE XXXIX. 



Bismuth. 



Thermo-electromotive Force, volts X 10^- 



volts per degree per kg. The value indicated by interpolation and 

 extrapolation of the data above is 531 X 10"^^. The agreement is 

 not good. In view of the great differences found in the previous 

 work in the electrical properties of bismuth of different origins, and 

 the large effect of minute impurities, it would have been most desirable 

 if ^Yagner had allowed some estimate of the purity of his sample by 

 stating its temperature coefficient at atmospheric pressure. 



