36 



Proceedings of the Royal Irish Academy. 



ion found in air we find a corresponding ion in COj. The mobilities of the 

 ions in CO. are, of course, smaller. The percentage of CO, present is given 

 for each determination, and the mobilities have been corrected to correspond 

 with pure CO2 on the assumption that the mobility varies inversely as the 

 square root of the density. The error involved in this calculation will not 

 be very great as long as the percentage of CO2 is not unduly small. 



Mobilities of Positive Ioxs in Moist CO,. 



Per cent. CO:. 



MoMity. 



Mobility in 



100 per cent. 



COj. 



Corresponding 

 Talue in air. 



Eatio. 



92 



10-2 



10-1 



12^2 



1-21 



(92 

 (92 



5-86 

 5-90 



5-78 j 

 5-82) 



6^62 



1-14 



92 



3-60 



3-55 



4-23 



1-19 



92 



2-64 



2-60 



3-00 



Mo 



97 



1-85 



1-83 



2-04 



1-12 



97 

 87 



1-60 

 1-55 



1-58 J 

 1-51 j 



1^79 



1-16 



96 

 87 



1-39 

 1-40 



1-37 J 

 1-37) 



l^o2 



Ml 



80 



1-21 



1-17 



1^37 



M7 



80 



•89 



•86 



1-06 



1-23 



Only a moderate degree of accuracy can be claimed for the mobility 

 values given in this table, as we were unable, for the reasons already 

 explained, to make a thorough examination. It is clear, however, that the 

 ionisation in CO, is of the same general character as that in air. The ratio 

 between the mobilities of the ions in air and of the corresponding ions (or, 

 at least, the ions which seem to correspond^ in C< '^ has a mean value of 1'16. 

 The ratio of the square root of the densities of these gases is 1-24. The 

 mobility of the last ion (-86) seems to correspond to the value reported for 

 COj by other observers. The corresponding ion in air (mobility = 1-06) has 

 not been investigated in the course of the present work, but has been found 

 by one of us previously, both in air ionised by a radio-active source and in 

 the air from a water-spray. 



