348 



BRIDGMAN. 



There are, therefore, considerable differences in the thermo-electric 

 behavior. We would expect large differences in the behavior under 

 pressure. 



The pressure measurements on Heraeus platinum were made in 

 an order the reverse of usual, beginning at 95° and ending at 25°. 

 On the first application of seasoning pressure at room temperature 

 the wire broke at 12000 kg. It was therefore evident that viscous 



Temperature 



Temperature 



Pure Platinum 



FiGUHE 34. Heraeus Platinum. On the left, the heat absorbed by unit 

 quantity of electricity in flowing from uncompressed metal to metal compressed 

 to the pressure indicated on the curves, as a function of temperature. On 

 the right, the excess of Thomson heat in metal compressed to the pressure 

 indicated on the curves over uncompressed metal, as a function of temperature. 



drag was going to be troublesome, and the reverse procedure was 

 therefore adopted to insure getting as many readings as possible 

 before rupture occurred. The four regular runs were successfully 

 made, but at 75° the effect of drag was very large. After the four 

 runs an attempt was made to repeat the run at 75°. Only three points 

 were obtained, at 0, 4000, and 8000 kg., the wire breaking again at 

 12000. The points obtained lay about 3% lower than those of the 



