RESIDUAL WATER NUCLEI. 



123 



(dn/dt = bn 2 ) several times as rapidly as the same ion in a dry atmos- 

 phere when tested by the electrical conduction of the medium. 



If but a part, n, of all the ions are captured, n' escaping, we may write 



dn/dt dn f /dt = bn 2 + 2 bnn' + bn' 2 

 so that both dn/dt and dn'/dt are larger than bn 2 and bn' 2 . If n = n', 



2dn/dt = 4bn 2 or dn/dt = 2bri* 



If but one-third of all the ions, 3^, are captured, dn/dl = g bn 2 ; etc. 

 Hence if but i/m of all the ions are captured, the coefficient of decay 



FIG. 40. (a) Decay of ionization in fog chamber in 

 lapse of seconds, n being number of nuclei per cubic 

 centimeter. (b) i/n in the lapse of seconds ob- 

 served and computed with 6 = 0.0014 when n is ex- 

 pressed in thousands per cubic centimeter. 



being as found should be about m times too large as compared with the 

 true values. This does not explain, however, why the coefficient 6 

 increases when t is larger and n is smaller; if it were additionally assumed 

 that the ions decrease regularly in size as they decay more and more, 



