lONIZATION BY NEGATIVE IONS 



9 



practically parallel to the axis of x for the low forces, so 

 that w , the number of ions produced by the rays, is 

 proportional to the currents for forces of 10 or 15 volts 

 per centimetre. The following numbers may be taken 

 as illustrations: 



In the experiments at a pressure of I'l millimetre, and 



180 

 160 

 140 

 120 

 100 

 60 

 60 

 40 

 20 



80 



160 



240 



320 400 



Volts per centimetre. 



Current-electric force curves for air at '385 mm. 

 pressure, with distances of 2, 1 and '5 cms. 

 between the plates. 



Figure 4. 



a force of 160 volts per centimetre the value of a deduced 

 from the curve, figure 3, corresponding to a distance of 

 2 centimetres between the plates is 2'02, and from the 

 second curve the value 1*98 was obtained. With the 

 same force and a pressure of *385 millimetre a increases, 



