THERMO-ELECTRIC QUALITY UNDER PRESSURE. 



321 



0.00-4 inch in diameter. Before the runs the wire was seasoned by a 

 single application of 12000 kg. at room temperature. At the first 

 run at 25° all four strands broke at the lower end above 8000 kg., 

 possibly due to cutting by the glass insulating covering during the 

 small motion necessarily incident to change of pressure. The appara- 

 tus was set up again, and three runs successfully made at 25°, 50°, 

 and 75°, but after 75° two of the strands broke, because of imperfect 

 functioning of the bye-pass on release of pressure, and the run at 97° 

 was made with the remaining two strands. 



The measurements of e.m.f. were regular and satisfactory. Equili- 



TABLE XVIII. 



Gold. 



Thermo-electromotive Force, volts X 10^. 



brium was rapidly reached, and there was no unsteadiness or other 

 evidence of internal instability. The maximum departure of any 

 observ'cd point from a smooth curve was 1.3% of the maximum effect, 

 and the average arithmetical departure was 0.2%. The maximum 

 readjustment necessary in passing from curves at constant tempera- 

 ture to those at constant pressure was 0.86%. 



The numerical values are shown in Tables XVIII and XIX and 

 Figures 19 and 20. The e.m.f. is positive, increasing regularly with 

 pressure and temperature to 5.76 X 10"^ volts at 100° and 12000 kg. 



