702 



Mr. J. A. Cunningham 



the 



Table XVI. 

 A = Cathode: K = Auode. 



Temp, of 

 Anode. 





Potential Difference. 





Current. 



Pressure, 

 mm. of 





















Defln. 



°C. 



A-K. 



A-B. 



B-D. 



(calc. 



A-D. 



(calc. 



D-K. 



Defln. 



Amps. 

 XlO 4 . 



Mercury. 











*obs.) 



*obs.) 



135 







0-55 



20 



! 632 



407 



90* 



497 



25-1 



8-37 



0602 



055 



20 



632 



410 



90* 





... 



25-3 



8-43 



- 



055 



20 



632 



409 



90 



499 



133 



251 



8-37 





'17-5 



484 



620 



400 



97 



497 



123 1 



21-6 



7 20 





i 17-7 



488 



623 



410 



91 



501 



122 



25-1 



8-37 





195 



530 





413 















209 



562 



623 



410 



92 



502 



121 ! 



250 



833 





,26-8 



693 



623 



410 



93 



503 



120 I 



255 



8-50 





30? 





623 



413 









25-7 



8-57 





46-5 



1093 



623 



409 



99 



508 



lis 



251 



8-37 





52-5 



1205 



623 



408 



99 



507 



116 ! 



250 



8-33 





63-0 



1390 



623 



408 



101 



509 



114 



24-8 



8-27 





73-2 



1563 



623 



407 



409 



103 



510 



113 



243 

 25-1 



8-10 

 8-37 



0-C50 



7(H 



1617 



623 



410 



101 



511 



112 1 



25-5 



8-50 





80-1 



1680 



(630) 



414 



(104) 



(518) 



112 ! 



25-1 



8-37 





80-6 



1685 



630 



430 



89 



519 



Ill 



251 



8-37 





81-0 



1693 ! 



640 



440 



90* 



530* 



(110) 







0-633 



653 



1430 



040 







530* 



112 



255 



8 : 50 









(640) 



452 



(72) 



(524) 



116 



25-5 



8-50 





533 



1220 



640 



452 



71 



523 



117 



26-5 



8-83 





20-8 



560 



640 



458 



60 



518 



122 28-9 



963 





2065 



555 



640 



450 



e^o 



515 



125 



24-7 



8-23 





20-7 



556 



640 



444 



70 



514 



126 



23-5 



7-83 



0-619 



90 



280 : 



640 



446 



64 



510 



130 



23-9 



797 





2-0 



78 : 



645 



416 



64 



510 



135 



241 



803 





1-2 



49 i 



645 



447 



63 



510 



135 



24-6 



820 





already been mentioned, the gas in this part of the tube 

 remained quite dark. But on allowing the current to fall 

 gradually below the above value a brilliant yellow positive 

 column began to rise up from the anode, and the potential- 

 gradient in this part of the discharge increased very rapidly. 

 It was at first thought that the tube had begun to leak rapidly 

 until a direct measurement with the Mc Leod gauge disproved 

 this. The cathode-fall had also only shown a very slight 

 diminution. And on increasing the current the potential- 

 difference (D— A) fell off again instantly to its former 

 immeasurably small value. 



While confirming the old well-known observation that at 

 ordinary temperatures the cathode-fall increases w r ith increas- 

 ing current-density, this table also shows that, on the other 



