MEAN RESULTS. 



37 



Since n = 6ms 3 /xa 3 approximately (where a is the optical constant 

 of coronas and 5 their angular diameter on a radius of 30 cm.) for a 

 given s, n varies as m. Therefore n must be increased to 2 .3 per cent 

 of its value per degree of temperature of the fog chamber above 20 

 C. In this way the corrected data of table 14 were found. 



TABLE 14. Nucleations (averaged in groups of 2 to 4 days) in the lapse of time. 

 o- 3 at dp/p = o.345, 1 and at 8p-(n-7t 1 )/(p-n)=o.^5. 



1 These will be considered in section 20. 



Table 14 also contains the data for the corresponding averages of 

 temperature, barometric pressure, and ionization, and all data have 

 been further given in the graphs fig. 10, with the times (abscissas) laid 

 off on a smaller scale to bring out the relative variations. It is again 

 apparent that no relation of the nucleation curve to the barometer 

 curve or to the ionization curve can be made out. On the other hand, 

 the vapor nucleations of the dust-free wet air in the fog chamber agree 

 very fully with the cotemporaneous variations of the temperature of 

 the fog chamber (not of the temperature of the atmospheric air without, 

 of which they are also independent). It is even possible to make out 

 the rate at which nuclei are produced when the temperature of the fog 

 chamber increases. Taking the mean trend of both curves (nuclei and 

 temperature), it appears that nearly 8000 colloidal nuclei are generated 

 (apparently) in dust-free wet air, by a rise of temperature of i C. 



20. Nucleations depending upon dp /p. In the above experiments 

 the nucleations were compared at a fixed value, 0.335, of the variable 

 [n Ti^)l (pTc}. If, however, the corresponding value of the 



