694 



Mr. J. A. Cunningham on tlte 



slight changes of pressure except at very high exhaustion. 

 At very high temperatures and low pressures the slight leak 

 did, however, produce quite appreciable effects, as is well 

 illustrated by the latter part of Table XIV. 



Fig. 3.— (Temperature = 1500° C.) 



-I ? -5 -4 b mm. of Mercury \§ 1-5. 



Pressure. 



cv 



2-5 



Table IX. 



Temperature of 

 Cathode K. 



1 



Potential Difference. 



Current. -r, 



.Pressure, 



















' 





E-A. 



Defln. of Amps. 



Mercury. 



Defln. 



° C. 



K-A. 



K — E. 



(calculated) 



Galvanr. X 10 4 . 





168 



468 



793 



336 



457 



25-2 84 





5-8 



195 





320 









2-7 



102 



804 



324 



480 



25-2 8-4 





7-8 



248 





318 











163 



455 



| 804 



330 



474 









197 



532 



... 



340 











20-2 



545 



1 - 



337 









1-8 



! 463 



1112 





306 





26-9 



8-97 





55-3 



1255 



747 



302 



445 









59-3 



1325 



752 



300 



452 









67-3 



1463 



793 



296 



497 









70-3 



1514 



798 



294 



504 



265 



8-83 





