422 C. JSarus — Decay of Ionized Nuclei. 



is larger (remembering always that the ionization is through- 

 out loiv) are then apparent. 



Exhaustions above the condensation limit of air fails to 

 bring out the usual high values of b, for the ionized nucleation 

 eventually emerges into the vapor nucleation of dust free air. 

 These high values appear if the exhaustion is low enough to 

 catch but few vapor nuclei while being high enough to insure 

 large coronas due to ions. 



Two series of experiments made with this end in view con- 

 firm the occurrence of large values of b associated with small 

 values of n, no matter how the latter are obtained. 



If the true equation of the decay curve, dn/dt y were known, 

 it would then be worth while to reduce all the data to a com- 

 mon scale ; but the graphs obtained show that the values of b 

 rather suddenly increase below 10 -3 ?? = 10, so that a simple 

 relation is not suggested for the reduction. 



The question arises incidentally whether the ions may not 

 vanish by accretion, i. e., their number may be reduced because 

 individual ions cohere ; in such a case the fog limits should be 

 reduced for which there is no evidence. There seems to be an 

 independent second cause for decay entering efficiently when 

 the nucleation becomes smaller. We may, therefore, pertinently 

 inquire into its nature. 



5. Case of combined absorption and decay of ions. — The 

 most promising method of accounting for the above results has 

 been suggested by the work done in connection with the behav- 

 ior of phosphorus nuclei.* There may be either generation 

 or destruction of ions proportional to the number n, present 

 per cubic centimeter, in addition to the mutual destruction on 

 combination of opposite charges. In other words the equation 



— dn J dt = a + en + bti* 



is now applicable, where a is the number generated per second 

 by the radiation, c the number independently absorbed per sec- 

 ond and hv the number decaying by mutual destruction per 

 second. Here c is negative for generation and positive for 

 absorption. If a is zero 



l/n = l/n D +(\/n +b/e) ( e c («~0 _ i), 



where the nucleation n and n occurs at the times t and t a 

 respectively. Hence, when c becomes appreciable 



dn I dt c 



75 = — + b, 



n n 



or the usual decay coefficient increases as n diminishes, becom- 



* Barns: Experiments with ionized air; Smiths. Contr., No. 1309, 1901, 

 pp. 34 to 36. 



