178 C. JBarus — Distribution of Nuclei. 



viz., whether all the X-ray nuclei have been caught and in how 

 far the exhaustions are below the point of spontaneous con- 

 densation of moist air. Accordingly larger pressure differ- 

 ences were applied. Table 3 gives a few examples. 



Table 3. 



— Nucleations n in 

 X-rays, 3*5 min 



17 cm 



thousands per cm 3 . Ti 

 . Angular aperture <p - 

 21 cm 



me of 

 = s/30. 



exposure to 



3l cm 



Side 



s = 

 10-"ji = 

 Ratio 



A B 



4-6 1-8 



35 1-9 



18 :1 



A B 

 3-9 2-L 

 27 3-5 

 7-7:1 



1 B 

 2-8 2.5 

 11 7-8 

 1-4:1 



Hence above Bp = 21 cm for this apparatus, nuclei show them- 

 selves on both sides and the question arises to what extent the 

 normal air nuclei or ions have been captured. At Sp = 31 cm , 

 the fog particles condensed on X-ray nuclei probably drop out 

 at once and the persistent corona observed is precipitated on 

 the normal or inseparable air nuclei stated. 



6. Spontaneoits condensation in moist air in the absence of 

 X-ray nuclei. — With the object of finding the pressure differ- 

 ence of exhaustion, 8p, corresponding to the lower limit of 

 spontaneous condensation of moist air without foreign nuclei, 

 experiments were first tried with a cock 3/4 inch in bore, in 

 the exhaustion tube. The results were identical on the A and 

 the B sides, as follows : 



Table 4. — Spontaneous condensation in saturated air. Angular 

 aperture 0=s/3O. 



8p = 





24 cm 



31 cm 



s = 





2-2 



2-7 



Repeated, s = 





2-4 



3-2 



s = 





2-1 



— 



Do., large filter, s = 





2'2 



3 5 



Do. s = 





1-9 



— 



Air over nights, s — 





2-0 



— 



Mean \ s = 





2-1 



3-1 



n = 





3,500 



15,500 



8p = 



22 cm , 



n = 





This indicates that at a pressure difference of about Sp = 22 cm 

 for the given apparatus and dust-free moist air, spontaneous 

 condensation with vanishing coronas begins, and that there- 

 after the coronas increase regularly-. 



In corroboration with the preceding, similar experiments 

 were tried with an instantaneous valve, opening with a ham- 

 mer, and having a clear bore of over one inch. The results 

 shown in table 5 were identical on both sides but unexpectedlv 



