CONDENSATION OF VAPOR AS INDUCED BY NUCLEI AND IONS. 



relative drop dp/p (which assumes that all the water vapor is expanded 

 adiabatically without condensation) be computed, the latter will vary 

 with temperature in a way correlative with the vapor pressures con- 

 tained in the former. The nucleations computed for this particular 

 series of values of dp/p will also vary, and the rate was found to be about 

 6000 nuclei per degree. This is so near the temperature effect given 

 in section 19 that there must be a common cause underlying both. 



FIG. 10. Vapor nucleation of dust-free air, temperature of fog chamber, barometric 

 pressure, and positive and negative ionization (the former with small circles) in 

 lapse of time, averaged for period two to four days. 



Hence in table n, n was also computed in its dependence on dp/p, 

 and advantage was additionally taken of the new values of n given in 

 Chapter III for the higher coronas. Two fiducial values of the variable 

 dp Ip were tested; the former, dp/p = o.T,4o, being, as a rule, too small, 

 the latter, dp/p = o.34$, was selected. The tables contain both of the 

 corresponding values of nucleation, n 340 and w 0345 ; but the last only 

 has been given on the charts (figs. 8, 9, and 10). The other does not 

 differ essentially from it. All values are summarized in succession in 

 table 15. 



