640 Prof. Townsend and Mr. Kirkby on Conductivity produced 



the experiments which we have given for low pressures the 

 electrometer-deflexions were too small to allow of very accu- 

 rate measurement, but we do not think that experimental 

 errors would account for the differences between the above 

 ratios and the ratio 4:1. 



Fur. 1. 



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From the curves given in figs. 1 and 2 an estimation can 

 be made of the number of new ions generated by a single ion 



