304 



Hon. R. J. Strutt on the Discharge of 



gas to the insulated quadrants of a quadrant electrometer. 

 This rate was first determined when both of the cells were 

 filled with air. The bulb was adjusted to such a position that 

 the rate of leak in each of the cells was very nearly the same. 

 One of the cells was then filled with helium, and the rates of 

 leak again compared. The ratio of these rates was corrected 

 for the slight inequality of the gas cells as determined when 

 both were filled with air. 



In this way the relative conductivities were determined. 



The electrical connexions are shown in fig. 6. 



Fig. 6. 



earth 



a represents the battery (100 cells). 



b, the cell containing the ionized gas. 



c, the electrometer quadrant. 



d, the bulb emitting the rays. 



a is the battery, consisting of 100 storage- cells. One 

 terminal is put to earth and to a pair of electrometer 

 quadrants. The other terminal to the outside of the cell b, 

 containing Rontgenized gas. The central and highly insu- 

 lated electrode of this cell is connected to the other pair of 

 electrometer quadrants. 



Suitable commutating arrangements, consisting of mercury 

 cups in paraffin blocks, are provided for throwing either the 

 air cell or the helium cell into the circuit. 



Supposing all to be in working order, the measurements 

 were made as follows : — The two pairs of quadrants were 



