Ionization by Charged Particles, 809 



the rajs liberated from A may strike A again and either 

 suffer a loss of energy or liberate new 8 rays. Nevertheless, 

 the results of the experiments are sufficiently interesting and 

 suggestive to be worthy of record. 



7. Fig. 2 gives the results of the measurements when Y 2 



Fior. 2. 



/ x i k * & j a i i*it ix 



is constant and Vj is variable. Any ordinate gives the 

 number of electrons having a velocity greater than Y 2 

 which emerge from A when the electrons from Z striking A 

 have a velocity denoted by the corresponding abscissa Y^ 

 It will be observed that, for all values of V 2 , the number 

 of rays emerging from A decreases as Vj increases for all 

 values of Y 1 greater than 6 volts. The absence of the 

 second rapid increase in the number of 8 rays with increase 

 in Yi, noted by Gehrts and v. Baeyer, when Y x exceeded 

 11 volts, is doubtless due to the action of the field between 

 A and Z, which tends to retain the electrons within A 

 and to prevent them from emerging. However, in the 

 dotted curve (obtained by subtracting the curve for Y 2 = 2 

 from that for Y 2 = 0), which gives the number of rays 

 emerging with a velocity less than 2 volts, there is distinct 

 evidence of the minimum at about 11 volts, followed by the 

 second increase which was noted by Grehrts. It appears, then, 

 that among the rays due to ionization there is a much larger 

 proportion of very slow rays than among those due to 

 reflexion. 



