McClelland And M'Hknry — Uncharged Nuclei. 



285 



For very slow blasts large ions were found with a mobility as low as 00024. 



The slower the air-blast the smaller was the mobility. 



Curves 1 represent the manner in which C2 and Ci decay with the time 



taken by the air to traverse the apparatus. The currents are, as throughout, 



C. 

 in arbitrary units. The manner in which — ' changes with time is also 



900- 



800 



700 



600 



500_ 



UOO. 



zoo. 



100. 



100 



CURVES 1 



o 



a 



k 



zo 



40 



60 



?o joo no luo 



Time. Un 1 1 nearly 1se 



sec 



shown. Ci, of course, is the current of small ions due to the uranium by 

 itself when no spark is playing. (L is the current of large ions due to the 

 charging by the uranium ions of the nuclei produced by the ultra-violet light. 

 The air in all these experiments passed over a water surface. For the 



