6 



Proceedings of the Royal Irish Academy. 



consistent and reliable results as regards the percentages of ions present 

 under diflerent conditions. Temperature fluctuations could hardlv liave been 

 the cause of the change. "S'ariations in the humidity of the air might possibly 

 explain the disappearance of the ion. Experiments with partially dried 

 air, carried out later, did not, however, explain the matter. 



Dried Air. Small Ions. 



Air was drawn through two towei-s containing calcium chloride, and 

 through two long tubes, which had layers of pliosphorus pentoxide on the 

 inside surfaces. This dried air passed through the cotton-wool plug and over 

 the phosphorus. We do not consider the drying produced by any means 

 perfect. It is very difficult to obtain perfect drying when considerable 

 quantities of room-air are being continually drawn in. The drying we used 

 is probably as good as can conveniently be obtained with these condi- 

 tions. The time-interval was approximately 8 sec. The results are given in 

 Table III («> 



Table III (a). 





•20: 



•095 



•053 



•026 



•021 



■0042 





•25? 



•086 



•061 



■032 



•018 



•0041 







•086 



•059 



•026 



■017 









•101 



044 



•028 



■016? 









■090 



•051 



•028 



•018? 









•094? 



■060? 



•030 











•090? 





•032 » 

 •027? 







Means, 



•■J2? ' 



•092 



•054 



•028 



■019 



-0041 



Table III [b). 



Means, 



23 



■092 



20 



■094 



24 



■089 



19 



■099 



27? 



■095 



•093 



With dried air we get three ions which were not present at the same 

 time-interval with undried air, viz., ions of mobilities -22, -092, -028. At 



