696 







Mr. J 



. A. Cunningham 



on the 











Table XII. 





Temp, of ! 

 Cathode. 



i 



Potential Difference. 



Current. 



1 



Pressure, 



Defln. 



°c. j 



K-A. 



K-D. 



d-aJd-b. 



I 



Defln. 



Amp. 



xio 4 . 



mm. 



i 



.1-9 



• 75 1 



525 



370 



148 



22-8 



7-60 



0-376 ; 



1-95 



76 1 





376 





119 







9-0 



280 1 





382 











162 



451 





388 





121 







192 



520 j 



535 



392 



152 



122 1 20-4 



6-80 





21-7 ' 



580 



535 



394 



152 



19-7 



6-57 





247 



648 



535 



393 



152 



... 197 



6-57 





28-0: 



720 



545 



395 



153 





192 



640 





40-7 



980 



(555) 



400 



155 





18-8 



6-27 





41-2 



990 



(548) 



393 155 





18-8 



627 





617 



1367 



(545) 



390 : 155 





18-6 



620 





66-4 



1450 



545 



392 ; 154 





i 18-5 



6-17 





71-4 



1533 



(553) 



392 ! 161 





18-3 



6-10 



0-406 



710 



1525 



550 



392 160 



128 









74-2 



1580 



555 



394 1 158 











77-4 



1634 



(545) 



388 



157 





17-8 



5 93 





790 



1660 



(528) 



375 



153 





180 



6-00 





81-2 



1696 





240 













77-7 



1638 



(523) 



372 



151 











85'0 



1750 



320 



190 



151 









0-392 



78-0 



1642 



470 



343 



148 





17-2 



5 : 73 





764 



1617 



525 



389 



150 











75-1 



1594 



560 



407 



150 











72-2 



1547 



570 



565 



i 415 



i 420 



150 



150 





170 



5-67 





53-0 



1213 



565 



1 412 



150 











34-2 



850 



580 



i 426 



152 





16-8 



5-60 





242 



637 



(575) 



! 423 



152 











8-0' 



250 



(542) 



' 390 



152 





16-8 



56 





37 



133 



560 



. 400 



151 





192 



6-4 



0-374 



3-6 



1 



130 



565 



1 404 













The results o£ Tables IX. and X. are plotted in fig. 4, 

 curves E and D respectively. The one was obtained while 

 the cathode was being warmed up, while the other was a 

 cooling curve, which may account for the shifting of the initial 

 minimum and maximum along the axis of temperature. The 

 curve D shows the potential-difference between the cathode 

 and a point in the top of the positive column (K — D). 



The results obtained at a rather lower pressure (about 

 1*1 mm.) are given in Table XI. and plotted in fig. 5, 

 where the cathode (K) is supposed to lie along the line of 

 zero-potential below the diagram, and the P.D. between it and 

 each of the electrodes A, B, and D is measured by the ordinate 

 drawn to the respective curve at any given temperature. 

 Here the initial variations (at a temperature below 600° C.) 



