PERSISTENT NUCLEI. 



2Z 23 24 2.5 



4- 8 to 



In the above charts, Tab. 12 is replaced 

 by the present table 39; Tab. 13, by the 

 present table 40; Tab. 14, by the present 

 table 41. 



"22. 19 20 **2T 



FIGS. 63-68. Illustrating tables 39, 40, 41. 



54. Persistent nuclei in general. It is not improbable that persist- 

 ency may generally be due to some cause favorable to the production 

 of water nuclei.* Those heavy rains, for instance, which accompany 

 the X-ray corona when the bulb is close to the fog chamber may be 

 due to the fact that condensation occurs spontaneously without the 

 need of supersaturation, if an exposure to very intense X-light is in 

 question. The nuclei in the X-field behave like hygroscopic bodies. 



* For more detailed statements see my investigation on the "Structure of the 

 Nucleus," Smithsonian Contributions, No. 1373, 1903. 



