28 



VAPOR NUCLEI AND IONS. 



removed by exhaustion, bring out the points just made with better 

 regard to the actual nucleation, seeing that the s-curves are specially 

 favorable to small numbers of nuclei. As a rule the new nucleations 

 obtained are nearly twice as large as the old results. It seems probable 

 that the upper inflection, after passing the nearly straight part, is due 



?80 



260 



240 



220 



200 



180 



160 



140 



ieo 



Fig. 20. Improved fog chamber. Efficient nucleation (n) free air cor- 

 responding to fig. 19. Table 10. 



to the waning condensing power of the apparatus, and that in the 

 absence of this loss of efficiency the middle region of the doubly inflected 

 curve would continue indefinitely. One may note, too, that both in case 

 of tables 7 and 10 the parts in question are nearly parallel, or that the 

 increment of nucleation corresponding to a given increment of super- 



