1909.] THE CORONAS OF CLOUDY CONDENSATION. 181 



the constant c furnishes a mean value for the factor on the left. 

 The ratio of 4.6 c to the measured value of (log RJR2)/l was 

 .568, a reduction factor used throughout the tables below. 



4. Method Pursued. — If C is equal to C" -\- C -{- c we may- 

 write the equation for the negative ionization N (positive charge) 



C\x\RJR^d{\nV) d {\n V) 

 60017 Ive di dt ' 



where R^, R^ and / are the effective radii and length of the con- 

 denser, io^^e = 2>A> ^=1-51 cm./sec, and w^i.37 cm./sec, the 

 velocity of the negative and positive ions in the unit field, volt/cm., 

 in case of moist air. The factor (In R^/R2)/l is replaced by 1/2C, 

 as specified in § 3, which must here be regarded as an adequate 

 correction for the ends and the imperfect cylindricity of the con- 

 denser fog chamber. 



Similarly the equation for the positive ionization is (negative 

 charge), 



^, ^ ClnRJ R^ d{\n V) ^ ^, ^(In V) 

 6oO'Trlue dt dt 



and the total ionization is therefore N -|- N' . 



The experiments below will show that even if the fog chamber 

 is put to earth, there is a drift towards negative potential, suffi- 

 ciently steady to be eliminated in the mean results. Hence if V ^ 

 be the effective negative potential of the wet glass envelope we may 

 write tentatively, 



(-« 



dt \ V ) dt 



where V ^ is intrinsically negative. 

 Similarly, 



-(-;") = ^''-^' 



Hence if V = V', N -\- N' the total ionization is again 



^(/clnF + K'lnF'). 

 Direct experiments, however, show that the drift results from 



