produced from a Gas by H'njli-Speed Cathode Rays. 219 



range v = 40 to v = 700 volts. Assuming an equation 

 j/ = V.v~ a , calculation by the method of least square gives 



y= 188. x-°'*\ 



The Table IV. for hydrogen leads us to the same conclu- 

 sions as in the case of air. The mean values in the last 

 column in this table are plotted in fig. G. 



Fig. 6. 



oesi ro-H con ocei ecu cooi oo 



IOB 001 009 COS 0017 OOC 00Z 00! 05 



50 HX 



The mean values are very close to the corresponding values 

 for air. Calculation gives an equation : 



■0-91 



over the range u = 40 to 700 volts. The difference between 

 the two exponents of x in the equations for air and hydrogen, 

 while not negligible, is not large. These results seem to 

 support strongly the fact that the distribution of velocities 

 with which these secondary rays are emitted does not vary 

 much with the nature of the atoms emitting them. This 

 property also agrees with that of 8 rays from metals (§ 1). 



For potentials lower than 30 volts, currents calculated 

 from the above equations do not agree with those obtained 



