692 



Mr. J. A. Cunningham on the 

 Table VII. 



Temp, of 

 Cathode. 



Potential Difference. 





Current. 



Pressure, 













mm. of 

 Hg. 



Defln. 



°C. 



K-A. 



K-E. 



E-A. 



E-D. 



D-A. 



Defln. 



Amps. 

 X 10 5 . 



65-5 



1432 



1350 



360 



990 



280 



720 





(2-6) 



213 



65-5 



1432 



1020 



328 



692 



190 



500 



oi 



3-06 



1-53 



65-3 



1429 



850 



(280) 



(570) 



120 



450 





(3-2) 



1-13 



65-5 



1432 



770 



300 



470 



100 



380 



5-9 



3-54 



1-07 



65-o 



1432 



650 



302 



348 



< 90 







(3-8) 



0-604 



65'55 



1434 



587 



328 



259 









(3-8) 



0-431 



65-5 



1432 



583 



370 



213 







63 



3-78 



0-226 



65-5 



1432 



680 



470 



210 



... 







(3-4) 



0122 



65o 



1432 



780 



510 



270 









(3-2) 



0-078 



65-5 



1432 



1110 



565 



545 



>310 



90 



3-9 



2-35 



0-035 



653 



1429 



1480 



430 



1050 



920 



150 







0023 



65-5 



1432 



2000 



















0017 



Table VIII. 



Temp, of 

 Cathode. 





Potential Difference. 





Current. 



Pressure, 

















mm. of 

 Hg. 



Defln. 



°C. 



K-A. 



K-E.l 



E-A. 



K-D. 



K-B. 



Defln. 



69-4 



1500 



1650? 



305 



1190 



(760) 





6-09 



2-95 



69-4 



1500 



1220 



293 



930 j 



340 



930 



1054 



2-20 



69-5 



1502 



970 



283 I 



670 j 



333 



720 



(16-4) 



1-60 



694 



1500 



800 



295 



490 ' 





610 



(22-0) 



1-20 



694 



1500 



690 



295 



380 



310 



500 



(28-0) 



0-71 



69-4 



1500 



635 



304 



326 



305 



435 



27-7 



0-66 



69-5 



1502 



580 



304 



280 



335 





2934 



0-50 



69-4 



1500 



575 



(335) 



240 



352 



472 



3244 



0-29 



69-4 



1500 



630 



420 



203 



508 



585 



3444 



0-18 



69-4 



1500 



, 750 



554 



194 



640 



700 



34-04 



0103 



69-4 



1500 



860 



614 



220 



740 



820 



(31-8) 



0078 



69-4 



1500 



960 



674 



262 



850 



905 



30-54 



0-058 



69-4 



1500 



1030 



695 



335 



900 



980 



30-00 



0056 



69-4 1 1500 



I 



1050 



700 



350 



920 



1010 



" 



0048 



At low temperatures of the cathode the " cathode fall " 

 (K — E) shows a well-marked minimum at a pressure of 

 about 0*65 mm. of mercury. At higher temperatures this 

 minimum tends to become less marked, and to occur at a 

 greater pressure. In fact the cathode fall becomes almost 

 independent of pressure above 0'5 mm. The cathode fall at 

 the highest (1500° C.) and at the lowest (35° C.) are plotted in 

 fig. 2. 



