188 BARUS— METHOD OF STANDARDIZING [April 24. 



When N is 1,700,000 the coronas are too diffuse for sharp speci- 

 fication. If it is assumed that negative ions only are caught, and if 

 the nucleations corresponding to the coronas seen in the given fog 

 chamber be taken as developed in my earlier work, then for 



N-i-N'= 1,700,000, 385,000, 135,000, 



the electron values are 



io'V = 4.4, 3.6, 3,9, 

 electrostatic units. 



With regard to the tv^o parts of this paper that need revision 

 the first, the comparison of the computed condenser capacity C with 

 a standard, is a minor matter; but the other, i. e., the marked dis- 

 tribution of ionization along the axis of the fog chamber, will need 

 further inquiry. In the direction of the exhaustion the amount of 

 ionization may vary in the ratio of more than i to 2, in a fog cham- 

 ber of about one half meter of length ; and this under conditions 

 where there should apparently be no variations and irrespective of 

 the production of radiation from within or from outside of the fog 

 chamber. 



Brown University, 

 Providence, R. I. 



