76 



BARUS— NUCLEI IN DUST-FREE WET AIR, 



[April 20, 



radiation as compared with a maximum number of ions produced 

 by that radiation is as follows; 



natured radiation, air 



Beta and gamma rays used. . 

 X-rays used 



Since the intensity of radiation is as the square of the number of 

 nuclei, an increase of the intensity of radiation from i to 10* and 

 from I to 10*' lowers the condensation limit (z/i/z^= 1.24), 1.2% 

 and 1.6%, respectively. 



6. Residual Water Nuclei. Behavior on Successiz'e Evapora- 

 tion of Fog Particles. — Water nuclei are obtained by the evapora- 

 tion of fog particles, on compression of the dust-free wet air in which 

 they are suspended. One may expect them to differ with the nucleus 

 or ion on which the fog particle is precipitated, and this is the case. 



zoo 



Figs. 6 and 7. The ordinates show the nucleation {n nuclei per cubic 

 cm.) obtained upon successive identical exhaustions and immediate evapora- 

 tion, thereafter, of the fog particles precipitated. The abscissas give the 

 number of exhaustions. The ions, the vapor nuclei of dust free air and 

 phosphorus, or solutional nuclei are contrasted. In the latter case, removal 

 by exhaustion is the only source of loss. 



