THERMO-ELECTRIC QUALITY UNDER PRESSURE, 319 



The thermo-electric behavior at atmospheric pressure against lead 

 is given by the formulas: 



E = (2.556 1 + 0.00432 f) X \0~^ volts, 



P = (2.556 + 0.00864 /) {t + 273) X 10-« volts, 



(X = 0.00S64(f + 273) X lO"" volts/°C. 



For the pressure measurements it was seasoned in the regular way 

 by two applications of 12000 kg. at room temperature. The readings 

 under pressure went perfectly smoothly, without incident of any sort. 

 The maximum zero correction was at 98°, 0.7% of the maximum effect; 

 there was only one bad point, at 10000 kg. and 75°, where there was 

 a discrepancy of 2.5%. Except for this, the maximum departure of 

 any point was 1.2%, and the average arithmetical departure from a 

 smooth curve was only 0.11%. In changing from the curves at con- 

 stant temperature to those at constant pressure the maximum read- 

 justment necessary was 0.3%. 



The numerical results are shown in Tables XVI and XVII and 

 Figures 17 and 18. At constant temperature the curves of e.m.f. 

 against pressure are concave toward the pressure axis, which is what 

 one would expect. At constant pressure, on the other hand, the curves 

 are convex toward the pressure axis. The e.m.f. is positive and in- 

 creases regularly with pressure and temperature. The Peltier heat 

 is positive and increases regularly with pressure and temperature. 

 The Thomson heat is also positive; it increases with rising pressure, 

 and at any constant pressure is proportional to the absolute tempera- 

 ture. 



Wagner gives up to 300 kg. and between 0° and 100° -|- 8.7 X 10~^- 

 volts per degree per kg., against 9.3 X lO""^^ interpolated from the 

 data above. 



Gold. This was the same piece of wire whose resistance was meas- 

 ured under pressure. It was used bare, in parallel strands. The runs 

 at 25°, 50°, and 75° were with four strands, but at 97° two only were 

 used because the other two had been accidentally broken during 

 manipulation. 



The thermo-electric behavior at atmospheric pressure against 

 lead is given by the formulas: 



E = (2.899^ -f 0.00467/2-0.00000166^3) y 10-« volts, 



P = (2.899 -{- 0.00934 ^-0.00000498 f-) {t + 273) X 10-« volts, 



<x = (0.00934/ -0.00000996 {t + 273) X lO^^ volts/°C. 



The manipulation demanded by the pressure measurements was 

 difficult because of the great fragility of the wire, which was only 



