9 2 



VAPOR NUCLEI AND IONS. 



suddenly at given intervals before exhaustion. Only very penetrating 

 primary rays (/? and y) are therefore in question. The curves show the 

 number of efficient nuclei in thousands per cubic centimeter, observed 

 after the lapses of time shown by the abscissas, and it is supposed that 

 the nuclei are reproduced faster than they can be removed by the ex- 

 haustion. In the upper curve the pressure differences applied (dp = 31) 

 are much above the fog limit of dust-free air, which is below dp = 24 for 

 the given apparatus. In the lower curve the pressure differences are 

 nearly at the fog limit of dust-free air, while the other curve (dp = 28) 

 applies for intermediate conditions. The effect of the radiation is there- 

 fore, virtually at least, a coagulation (to use a figurative expression) of 



Table 37. Falling to pieces of ions produced by radium. Everything ready; 



cocks closed before removing radium. 



Date. 



Oct. 19 



t* 



s. 



Cor. 



nx io" 



0/1 = 31 cm. 



dp = 24.5 cm. 



140 



76 



24 



5i 



82 



in 



134 



145 



79 

 45 

 36 

 18 

 16 

 1 1 

 3-5 

 45 

 29 

 23 



Date. 



I* 



s. 



Cor. 



nx 10 



-3 



dp = 28 cm. 



Oct. 25 



sec. 

 o 



15 

 30 

 45 

 60 

 120 

 180 

 00 

 00 



wrg 

 w o g 



72 



21 

 16 

 13 

 14 

 40 



37 

 37 

 43 



Oct . 2 7 Repeated . Decay of ions at dp 24. 



Radium on. . 

 Radium at 00 

 Radium on . . 



2.5 



1.6 

 12. 1 

 11. 4 



25 

 36 



77 



Fog limit of air. Radium off. 



67> = 2 3 .6 



dp = 22.6 



i-3 

 .0 



i-5 

 .0 



* Seconds elapsed after removal of radium. 



t First coronas dense but fall out rapidly, leaving fainter and smaller coronas behind. 



