420 C. Bar us — Decay of Ionized Nuclei. 



times, t, a somewhat irregular increase of 5, was observed as n 

 decreased. When the first observation was combined with the 

 fourth, etc., the values were, x — - 29 being the relative drop 

 of pressure, 8p/j), 



b = -0029 

 34 

 36 

 41 



or a mean value, b = -0033 (n reckoned in thousands), if the 

 last observation is ignored, since the coronas are just visible 

 here. 



If the electrical datum, b — "0014 be correct, the present 

 nucleations n are to be increased on the average, •0003/ - 0014 = 

 2*3 times. If the last datum for b were included much more. 

 This is quite unreasonable. One must conclude therefore that 

 b for nuclei is larger than b for ions or that an ion, acting as a 

 nucleus in a saturated atmosphere, decays {dn/dt=—bn) sev- 

 eral times as rapidly, as the same ion in a dry atmosphere 

 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' / dl = bn 2 + 2 bnri + bn' 2 



so that both dn / dt and dn' / dt are larger than bn 2 and bn' 2 ; 

 If n = n' 



- 2 dn / dt — 4 bn\ or — dn / dt = 2 bn 2 . 



If but 1 / 3 of all the ions, 3n, are captured, — dn / dt — 9 bn 2 ; 

 etc. Hence, if but 1/m of all the ions are captured the coeffi- 

 cient of decay being as found should be about m times too 

 large as compared with the true value. 



This does not explain, however, why the coefficient b 

 increases when t is larger and n is smaller ; if it were addition- 

 ally assumed that ions decrease regularly in size as they decay 

 more and more, so that they withdraw more and more fully 

 beyond the given range of supersaturation applied, the second 

 part of these occurrences would also be accounted for ; but the 

 assumption is not probable. 



3. Exhaustion below the fog limit of dust free air. — It would 

 follow from what has just been stated that if the drop of pres- 

 sure is lower, the values of b obtained must be larger. For not 

 only are few of the ions caught but the diminution of bulk 

 (virtually) which may accompany the decay would place them 

 sooner out of reach of the given exhaustion as the interval of 

 decay increases. But in experiments of this kind, the succes- 

 sive values of b again show an outspoken march into larger 

 values as the time t increases. 



