8o 



VAPOR NUCLEI AND IONS. 



In table 28 and fig. 38 the occurrence of periodic variation in the 

 angular diameter of successive coronas and the corresponding efficient 

 nucleation is shown by the same method of a permanently opened filter 

 cock. The conditions of all of the exhaustions are quite identical; but 

 the small fog particles of large coronas evaporate faster and in greater 

 numbers than the larger particles of smaller coronas. Hence the water 

 nuclei are present in like periodic distribution. The effect is more 

 striking when the stopcock is opened wider. The difference between 

 180 and 90 in the adjustment of the cock is not marked, because the 

 filter itself introduces resistance to flow. 



Table 28. Corresponding to table 27. Periodicity due to permanent open filter cock. 



w o g. 



3 Blurred with rain. 



2 w r g. Note the periodicity of the series. 4 g B p. 

 Table 29. Corresponding to table 27. Effect of dp; cock open during exhaustion. 



