Cathode Fall from Hot Carbon, 



201 



its value cold, marked (R) on the curves, correspond approxi- 

 mately to temperatures* of 1:500°, 1150°, 1170°, 1510°, and 

 1670° respectively from left to right on the 



Table I. 









Current. 





P.D. in 



rest of 

 Tube 



(A-B). 



Number 



Temp. 



«. 



Kg 



Pressure 

 mm. 



Deflexion 

 observed. 



2S75 = 10-oA. 



Cathode- 

 Fall 



(C-K). 



of equi- 

 distant 

 Bright 

 Bands. 



•552 



038 



166 



56*3 



(20) 



123 



5 







225 



765 



(80) 



117 



4 







260 



88-3 



200 



97 



3 







27-6 



940 



312 



(90) 



2J. 







29*0 



98-6 



380 



(60) 



2 







311 



105-8 



460 





1* 







37-7 



324 5 



128-3 

 1993 



606 

 515 





a 



H 





0-38 







365 



123-8 



583 











425 



144-7 



663 





if 







520 



176-8 



727 





j. 



•519 



0-45 



113 



316 





125 



5 







203 



568 



250 



95 



3 







277 



776 



285 



(95) 



2* 







353 



988 



315 





2 

 4 



•541 



0-40 



7-2 



201-6 



(10) 



103 







91 



249 



300 



90 



2 







11-4 



319 



550 





1 



•566 



0-56 



14-4 



144 



150 



100 



6 







198 



198 



270 



98 



5 







247 



24 7 



398 



97 



4 







291 



291 



461 



97 



o 



These curves show a remarkable general resemblance 

 (though on a much larger scale with respect to current) to 

 those characteristic of all conduction through gases (e. g. to 

 that produced by ultra-violet light striking a metal immersed 

 in the gas), where we first attain a saturation current ; and 

 then, on further increasing the P.D., we find greater con- 

 ductivity produced a- the result o£ the ionizing collisions of 

 the negative ion-. J>ut tiii- i- just the stage which i> ordi- 

 narily regarded a- initiating the luminous discharge. We 

 have then here evidently reached a region of rapidly 

 increasing ionization by collision, though such ionization 

 must have been going on even during this comparatively 

 u saturated " current (represented by the steep portions in 



* Extracted from Blaker'e r&umeoi Le Chatelier's results, loc. cit. 



