84 



VAPOR NUCLEI AND IONS. 



o / ^ 3 4 5 6 



Fig. 39. Nucleation (ions) produced by a 

 radiating X-ray bulb (cased in lead or 

 not as stated), at different distances (D) 

 from the glass fog chamber. Table 32. 



zoo 



ISO 



160 



140 



JZO 



100 - 



80 



60 



40 



20 



Fig. 40. The same, illustrating table 15, 

 Chapter II. 



The curves I and II, fig. 39, for the free bulbs show different nuclea- 

 tions, compatibly with the different values of dp applied, but are other- 

 wise alike in character. They in no way suggest the law of inverse 

 squares. The curves III and IV for the inclosed bulb are again similar 

 in character, but beyond this very little can be stated. If in case of 

 series II and III, for instance, the law 



n (A +D) 2 = const. 



is assumed, the constant A would have to be from 1.2 to 2.7 meters in 

 the first case, and 1.5 to 2.1 meters in the second, which is entirely 

 out of the question for a fog chamber less than 0.5 meter long. If the law 



n (A +D) = const. 



is used, in the first case (II) A =0.3 to 0.1 meter; in case III, A = 0.2 to 

 - 0.6 meter. This decrease would then be too fast in the first case and 

 too slow in the second, or the decrement in case of the open bulb is 



