Periodicity of the Spontaneous Ionization of Air, etc.. "Ill 



periodic variation; and hence we are forced to conclude that 

 this periodicity is independent not only of the gas enclosed 

 in the vessel but also of the metal of which the vessel is 

 made. Mean curves for the three different sets of curves 

 already given were drawn and are represented in fig. 4. 



Fisr. 4. 



1-4 



1-2 



|..o 



















































Pi 



r. A 



AD 





















































CO 



in 



rVfc 





















































































































































































































































































U 



At 



' 





















































m 



>o 



Co 



c 

















































































































































































7 



N 



9AI 







































Co 



































































































































































































































10 12 14 16 18 20 22 

 //oues of rue o*y. - — v 



24 



This brings out the similarity still more clearly, and is 

 sufficient justification for drawing a single mean curve to 

 represent the three sets of results. This is shown in fig. 5 

 (p. 272). 



For subsequent results it will be more convenient to draw 

 our curves in a somewhat different way. It was assumed 

 that the permanent increase of ionization which took place 

 from day to day with lead and with zinc (when coal-gas was 

 enclosed) was uniform throughout each day. Its value was 

 found by comparing the mean values of the ionization on 

 each of two consecutive days. The corresponding day's 



U2 



