72 CONDENSATION OF VAPOR AS INDUCED BY NUCLEI AND IONS. 



ionizations. If the two curves between 0.8 and 1.2 volts be considered, 

 the mean ionization of each is 







Apparent positive ions, negative charge N= 540,000 



Apparent negative ions, positive charge N' 1,164,000 



Total true ionization N + N' = 1,704,000 



Total nuclei caught 650,000 



It will be seen that N + N' is the true total ionization positive and nega- 

 tive, if io 10 = 3.4. Only 65/170, or about 38 per cent, of this is actually 

 caught in the given fog chamber on exhaustion, provided the old coronal 

 values are correct. 



If, however, it is assumed that negative ions only are caught during 

 exhaustion in the fog chamber in question, then the value of the electron 

 would be 



io 10 <? = 3.4X2.62X- = 4.4 electrostatic units. 



2 



61. Data. Moderate ionization. Electrical currents. These results 

 were obtained by placing but one radium tubelet, No. IV, in the alumi- 

 num tube it' of the condenser fog chamber (fig. 19). The data were 

 assembled in the same way as the above, N = Kd(\og V")/dt, as usual, but 

 they are here withdrawn, as they are sufficiently reproduced in the curves 

 (figs. 22 and 23). In the first and second parts of the table positive charges 

 only are treated and the results show the apparent negative ionization. 

 In the third part of table 23, however, both currents are observed in 

 succession and the true total ionization is TV+TV' as before. Moreover, 

 in parts i and 2 the capacity of the condensers is widely varied, 410 to 

 1459 cm., without showing serious divergence; though to bring this effect 

 out fully both positive and negative currents should have been averaged. 



62. The same. Coronas. At a fall of pressure of 2 1 cm. or dp/p o. 2 7 , 

 the nucleation was stationary and equal to N == 1 13,000 in the exhausted 

 fog chamber. At atmospheric pressure, therefore, 113,000X1.37 = 154,000 

 nuclei should have been present. The effect of a charge on the core of 

 the condenser did not appreciably diminish the nucleation or at least the 

 estimate could not be pushed below about 140,000. 



63. The same. Summary. For the case of the third and fourth parts 

 of table in question the successive observations at intervals of 30 seconds 

 apart are shown in fig. 22, the slopes only being of interest. The appar- 

 ent values of TV are given (fig. 23). Though the positive and negative 

 currents are both taken in one section only, parts 3 and 4, all the four 

 series show about the same drift, even though taken many days apart. 

 The condenser effect (excessive rapidity of needle) may be considered 

 eliminated for capacities greater than 500 cm. 



