372 A. W. Ewell — Air in an Intense Electric Field. 

 Conditions identical except air thickness = 1*31. 



E.m.f. 



36500 



39300 



34200 



31700 



29300 



27000 



24600 



Current. 



6-20 



6-60 



5-70 



5-00 



3-80 



2-64 



1-48 



E.m.f. 



22200 



23000 



37800 



39300 









Current. 



•54 



•71 



6-50 



6'90 









July 6. 



Dry. Bar. — 75*9, Temp 



..==20°. 



Air thickness : 



_ . 20 cm 



E.m.f. 



40200 



38000 



36200 



34200 



31800 



29000 



26300 



Current. 



7-80 



7-30 



6-70 



6'30 



5-60 



5-00 



4-35 



E.m.f. 



42300 



39500 



37500 



41500 



23200 



21500 



19300 



Current. 



8-20 



7-60 



7-00 



7*90 



3-70 



3-30 



2-75 



E.m.f. 



15300 



12500 



10500 



13800 



17000 



8500 



39500 



Current. 



1-88 



1-26 



•95 



1-61 



2-30 



•60 



7-40 



Identical conditions except air thickness 



== 2-41. 







E.m.f. 



40700 



40000 



38200 



39000 



36800 



35200 



35700 



Current. 



690 



7-00 



5*70 



6-40 



5-00 



2*75 



3-55 



E.m.f. 



37000 



38500 



40500 



40000 



32800 



31300 





Current. 



5-00 



5*80 



6'60 



6*50 



1-44 



•48 





These results are plotted in fig. 3 and full lines are drawn 

 through the observations. The dotted curves show the rela- 

 tion between the e.m.f. applied to the air and the ionization 

 current and are calculated, as described above, from the full 

 curves. 



As a check upon these observations, similar experiments 

 were made with a different glass. 



Glass =r Window glass 70 cm X 90 cm , average thickness = '24. 

 July 7. Dry. Bar. = 755, Temp. = 17°. 



Tinfoil electrodes, pasted on glass, similar to those used with 

 plate glass. 



E.m.f. 26000 24000 22300 21200 19700 18400 15700 



Current. 10-10 9'40 8 80 8-20 7'70 700 6'20 



E.m.f. 13700 11300 9500 6300 5000 4300 



Current. 5'40 440 3 65 2'57 1'95 2-63 



Jc= 6'7. 



July 9. Damp. Bar. 75'3, Temp. = 21°. 



Tinned copper electrodes described above. Thickness of air = 

 1-66. 



E.m.f. 

 Current. 



E.m.f. 

 Current. 



32000 

 10-00 



24800 

 9-50 



31000 

 8-50 



23500 

 4-40 



29300 

 6-90 



31700 

 9-40 



27500 

 5*70 



26500 25500 

 395 2-55 



