I909.] THE CORONAS OF CLOUDY CONDENSATION. 187 



13. Data: Small Ionization: Electric Currents. — In the next 

 series of experiments the aUiminum tube tt', Fig. i, was surrounded 

 by a lead tube with walls .117 cm. thick, leaving the y rays only 

 effective and these much reduced in intensity. The data are suffi- 

 ciently given in the following charts. 



14. The Same: Coronas. — The coronas found at a drop of pres- 

 sure similar to the above hp/p = .300, corresponded in my tables to 

 46,200 nuclei in the exhausted fog chamber. Hence at atmospheric 

 pressure there should have been 64,000. The effect of charging the 

 core was not definite. 



15. The Same: Summary. — The drop of potential in scale parts, 

 in successive intervals 30 cm. apart, is given in Fig. 40^ showing how 

 much slower the negative charges are lost than the positive charges. 

 The apparent values of A'^ are given in Fig. 4, to which remarks 

 similar to those already made are applicable. There is the usual 

 drift and the usual temporary fluctuation. 



If the mean data be taken between V=i.i and 1.4 volts, the 

 results are 



Apparent positive ions. A'"' = 37,000. 

 Apparent negative ions, N = 98,000. 

 True total ionization, N -\- N' =i2)S,ooo. 

 Total nuclei caught, 60,000. 



It follows, then, that about 44 per cent, of the total ionization 

 computed from 10^^^ = 3.4, u and v, is caught on condensation. 



If we suppose the negative ions only are caught in the above fog 

 chamber the electron value is 



e X io^° = 3.4 X 2.3 X i = 3-9 electrostatic units. 



Conclusion. — Supposing the electron value to be 10^°^ = 3.4 elec- 

 trostatic units as before, the normal velocities of the ions in wet air 

 to be ?<=i.37, ^-=1.51 cm./sec, in the volt/cm. field, the coronal 

 equivalent of the ions caught in the above fog chamber is in the 

 several cases, 



Total ions, 1,700,000, Total nuclei, 38 per cent. 



385,000, 47 per cent. 



135,000, 44 per cent. 



