34 NUCLEATION OF THE UNCONTAMINATED ATMOSPHERE. 



values are followed by high superior values. The oscillatory curves 

 usually rise [from great depth to great height. The ^-curves sometimes 

 show a tendency to double inflection after 8/> = 24 cm. is exceeded, ref- 

 erable, it would seem, to the normal air ions added to the radium ions. 



FIG. 26. Number of efficient nuclei (n) obtained in successive exhaustions of dust- 

 free air energized by radium. Periodicity. 



FIGS. 27-30. Change of apertures (s) of coronas and nucleations (N) varying with 

 the pressure differences (5^>) in cases of dust-free air energized or not by 

 radium (in sealed glass). Arrows show the march of the observations. 

 Periodicity is apparent. 



FIGS. 31-32. Decay of nuclei produced by radium after removal of tube from fog 

 chamber. Radium in glass tube. 



Table 9, referred to in figs. 26, 27, and 28, will be found as table 18, p. 33. 

 Table 10, referred to in figs. 29, 30, 31, and 32, will be found as table 19, p. 35. 



