THERMO-ELECTRIC QUALITY UNDER PRESSURE. 



329 



observed point from a smooth curve was 3.6%, and the average 

 arithmetical departure 0.72%. The maximum adjustment in passing 

 from constant temperature to constant pressure curves was 2.3%. 



The numerical results are shown in Figures 23 and 24 and Tables 

 XXII and XXIII. At constant temperature the e.m.f. curves are 

 convex toward the pressure axis, which is unusual, but at constant 

 pressure the curvature is convex toward the temperature axis, as is 

 normal. The e.m.f. is positive, increasing regularly with pressure 

 and temperature to 11.4 X 10~« volts at 100° and 12000 kg., but it is 



TABLE XXII. 



Nickel. 



Thermo-electromotive Force, volts X 10®. 



not as large as one would expect from the thermo-electric activity 

 of nickel against other metals at atmospheric pressure. The Peltier 

 heat is positive, increasing with pressure and temperature. The 

 Thomson heat is also positive, but at low pressures it passes through 

 a minimum with rising temperature and at high pressures it decreases 

 over the entire range with increasing temperature. 



^Yagner's value up to 300 kg. between 0° and 100° is + 9.6 X lO'^^ 

 volts per degree per kg. against 8.4 interpolated from the data above. 

 The difference may well be due at least in part to insufficient purity 

 of my specimen. 



