88 



NUCLEATION OF THE UNCONTAMINATED ATMOSPHERE. 



TABLE 55. Radium effect from different distances outside of fog chamber. 2^=25 

 cm. Wood fog chamber in lead casket. First exposure 5 min. Radium in sealed 

 aluminum tube. 



* Five or six periods observed in succession, same amplitude. 

 \ Radium effect lost at once ; apparent air periods. 



TO. Glass fog Chamber Penetration It seemed necessary to repeat 

 the work on the penetration of radium radiations as well as the exper- 

 iments on their effect from a distance with the aid of the cylindrical 

 fog chamber of glass ; for a vessel of this type may be made rigorously 

 tight, whereas entire freedom from leakage is often difficult to main- 

 tain in the plate-glass apparatus. From what has been stated, leaks 

 of any kind, even if small, are favorable to the occurrence of water 

 nuclei and therefore to periodicity. The data are given in table 56 

 and curves 88. 



tAworption /m J% tuleA*. Jal 29' 



J)--0 20 



40 60 80 /OO 120 



FIGS. 88-90. Illustrating table 56. 



160 



