46 CONDENSATION OF VAPOR AS INDUCED BY NUCLEI AND IONS. 



In the third part of the table the occurrence of the maximum at 50 cm., 

 for radium placed at 80 cm. from the exhaustion end, is again brought 

 out. Furthermore, the destructive effects of electric charge on the insu- 

 lated aluminum core extending from end to end of the fog chamber are 

 clearly manifest, the number of ions being everywhere relatively very 

 small. Specially favorable conditions obtaining in some of these experi- 

 ments are accompanied by comparatively large ionizations with the 

 uncharged core. This part of the table also contains an observation 

 proving that if filtered air enters at either end of the fog chamber, the 

 result is the same. Identical displacements were observed. In other 

 words, there is no deficiency of saturation involved in the occurrence in 

 the results in question, nor any difference between the freshly filtered 

 air and the stagnant residue in the fog chamber, nor any effect attribut- 

 able to parts of different material. 



ZOO 







30 40 50 60 70 80 90C02. 



FIG. 15. lonization at different points along the axis of the 

 fog chamber for different positions of the sealed radium 

 tubelets within the aluminum core. Position of lines of 

 sight shown on the curves. 



