78 



BARUS— NUCLEI IN DUST-FREE WET AIR. 



[April 20 



Since x is not constant the equation for the second exhaustion 

 should read n^yxU^ ; for the third n^y-xx'Ii^ ; etc. 

 It will then be found that for ions 



data which are somewhat irregular, but accentuate the importance 

 of the first evaporation. 



Special experiments showed that the loss in question is specifi- 

 cally due to the evaporation, and not to time, as, for instance, the 

 loss by diffusion of small nuclei would be. If the time interval 

 between exhaustions is doubled or trebled, etc., there is no corre- 

 sponding difference in the result. 



7. Decay of Ionized Nuclei in the Lapse of Time. — If n be the 

 number of nuclei per cubic centimeter, a the number generated per 

 second by the radiant field, hn"^ the number decaying per second, 

 dn/dt^a — hn~. If the radiation is cut off t seconds before ex- 

 haustion, a^o, dn/dt = — bn- or i/ti = l/n^^ -\- b(t — t^). Thus 

 the relative nucleation may be found if i* is known. If Uq/u is also 

 known, given for instance by the above method of geometric se- 

 quences, the absolute nucleation «o=((;io//0 — i)/^(^ — ^0) is 

 determinable. 



The result of this apparently straightforward method leads to 



grave complications, inasmuch as b is not constant but increases 



rapidly as the number of nuclei is smaller. Its value moreover is 



usually twice as large as the electrical coefficient b^i.4X lO"''. 



Thus in Table II, 



Table II. 



By taking the first and fourth observations, etc. 



