18 



Proceedings of the Royal Irish Academy. 



rendered very small ; and, in the second place, saturatior, of the ions was 

 produced at voltages high enou.gh to enable good curves to be drawn. 



The negative ions are again in excess. The ratio of negative to positive 

 is higher than in the case of the slower ions. Some of the more mobile ions are 

 about twice as numerous as the corresponding positive ions. As far as can 

 be seen, there is no difference between positive and negative in respect to the 

 values observed for mobilities. 



Tables are given, as before, of the mobilities of positive and negative ions, 

 classified into groups as observed with different rates of drawing air. 



Table IVa. 

 Mohilitics of Positive Ions. 



Rate of Drawing Air 



6 



7 



8 



9 



10 



11 



12 



3 litres in 39 sec. 



— 



— 



•55 



— 



— 



— 



— 



20 „ 



— 



— 



— 



1-0 



— 



— 



— 



14 „ 



— 



— 



— 



— 



1^9 



3 



— 



■4-n „ 





•20 



— 



— 



— 



— 



— 



3-2 .. 



— 



— 



— 



— 



l^o6 



— 



8? 



2 „ 



■14 



■27 



— 



— 



1-6 



— 



— 



Table IV&. 

 Mobilities of Negative Ions. 



Rat of Drawing Air 



6 



7 



8 



9 



10 



11 



12 



5 Hires in 26 sec. 



— 



— 



— 



1^08 



— 



— 



— 



''0 



— 



— 



•55 



1^08 



— 



— 



— 





n .> 



— 



— 



— 



— 



1^9 



3 



— 





> ' )> 



— 



•22 



•39 



M2 



— 



— 



— 





4-3 „ 



■12 



•20 



— 



— 



— 



3-7 



9? 





4 >, 



— 



•22 



•43 



MS 



— 



— 



— 





3-2 „ 



— 



— 



— 



107 



1^45 



3-1 



6-2 



1 



2-2 „ 



•09 



•19 



■39 



MO 



— 



— 



— 





2 >, 



— 



•27 



•51 



1^10 



1^60 



3^67 



6-5 





; 1-7 „ 



•13 



•29 



•55 



— 



1^60 



3-6 



— 



An inspection of the table of negative ions shows that the mobilities are 



