128 



BRIDGMA.N. 



acteristic of kerosene which has been exposed to high temperatures 

 and pressures. It would be of interest if the vapor pressure measure- 

 ments of Professor Smits could be repeated on this specimen. 



The specimen so formed was dried in vacuum for a number of hours, 

 at 125°, and sealed into an exhausted glass tube until ready for use. 

 It was cut to the same dimensions, and mounted in the same way as 

 the other specimen. Three runs were made with this, at 0°, 51°, and 

 95°. In addition to the temperature seasoning incidentally done when 

 it was heated in vacuum, it was given a pressiu-e seasoning by an appli- 

 cation of 12000 kg. at 0°. The runs all went smoothly; parasitic 



TABLE XVII. 

 Black Phosphorus. 



e.m.f.'s were no larger than would be expected from the high thermal 

 e.m.f. of this material, the behavior was perfectly reversible with 

 ascending and descending pressure, and the alteration of zero after a 

 run was no larger than the irregularities of any other of the observed 

 points. 



The outstanding feature of the results is the exceedingly large 

 decrease of resistance brought about by pressure, much larger than for 

 any other substance which I have measured. At 0° and 12000 kg. 

 the resistance is only 3% of its value at atmospheric pressure. The 

 ordinary method of plotting is not adapted to such a wide range 



