290 



Scientific Proceedings, Roijal Dublin Society. 



of mobility "014 are nearly 50 per cent, of those formed in moist air. In dry 

 air the largest ion is saturated at 8 volts, indicating an ion of mobility '07, 

 which, as is evident from the curve, forms only about 7 per cent, of the total. 



yo\ts 



In all probability rigorous drying would remove the effect altogether, but 

 in the experiments tried by us a small number of nuclei was always formed 

 in dry air. The effect in ordinary air depends, of course, upon the humidity 

 of the atmosphere, but is less than the effect in air passed over a water 



