214 Prof. Rutherford on Dependence of the Current through 



Using a thin layer of radium chloride, the intensity of the 

 radiation was found to be about 1/10 of its value at the 

 surface after passing through a distance of air of 3 centim., 

 and diminished approximately in G.P. with the distance. 



Fig:. 1 a. 













__ r — 



£00 

 '175 





















-*- + 













150 

 1E5 









r x / 









f 











/ / 









100 























75 

 50 













/ / 











25 

 n 



f 



/=>D. 



//V l/OLTS. 







50 



300 



450 



600 



Potential- Gradient between Plates. 



J. J. Thomson * has worked out the mathematical theory 

 of gas-conduction, due to distributed ions, under certain 

 special conditions. He has shown that in the case of uniform 

 ionization, the equation is not integrable in the practicable 

 case when the ions move with different velocities. The 

 present case is still more complicated than the one con- 

 sidered ; for, in addition, the rate of production of ions is 

 not uniform between the plates. Some light is, however, 



* Phil. Mag. March 1899, 



