14 



Proceedings of the Royal Irish Academy. 



Positive and Negative Ions. 



The negative current is always greater than the positive. Tlie ratio of 

 negative to positive when saturation is obtained is about 1'25. 



The five groups investigated so far are found both with positive and 

 negative ions. The actual values of the mobilities are the same foi' both as 

 far as can be determined. 



E/fect of Time. 



In the case of ions derived from Hames, it is found that the mobilities 

 decrease rapidly with time. If sufficient time is allowed, the ions come to a 

 stable mobility, having a value of about -0003 cm. /sec. It is important to find 

 if the mobilities of the ions produced by spraying depend upon the time 

 intervening between their production and observation. 



Table la. 

 Mohilities of Positive Tons. 



Rate of drawing air 



1 



2 



3 



4 



■ 5 



(a) 5 litres in 377 sec. 



•00038 



■00107 



•0052(?) 



— 



— 



(*) n 150 „ 



■00039 



■00096 



•0039 



— 



— 



W „ 75 „ 



■00038 



■00088 



~ 



— 





« ., 15 „ 



— 



— 



•0043 



•0097 



— 



W ,- 20 „ 



— 



— 



•0047 



— 



— 



(/) • „ 7 „ 



— 



— 



— 



•013 



•Oio 



W „ 1-8 „ 



— 



— 



— 



— 



•048 



Table I&. 



Mohilities of Negative Ions. 



Rate of drawing air 



1 



2 



3 



4 



5 



(i) litres in 150 sec. 



•00035 



•00116 



■0045 



— 



— 



W „ 75 „ 



•00036 



•00120 



■0055 



•013 



— 



('0 ., 4.5 „ 



— 



— 



•0037 



■013 



— 



(?) „ 2 „ 



— 



— 



— 



— 



<060(?) 



(i) ,. 1-7 „ 





— 



— 



— 



■040(?; 



