Ill'fl 



212 Mr. M. Ishino on Velocity of Secondary Cathode Rays 



respect to the electrode E did not prevent the reflexion of 

 the secondary rays from the electrode. This defect accounts 

 in part for the positive current. This arrangement was 

 abandoned as unsatisfactory. 



§ 7. Effects due to Rontgen Rays. 



Rontgen rays would be produced from the gas molecules 

 under the bombardment of the high-speed primary cathode 

 rays. Some effects due to the Rontgen rays were observed. 

 With a brass electrode not covered with soot, the experi- 

 ment described in § 6 was tried. The results are shown in 

 curve II. fig. 4. The amount of the negative current is 

 always less than that in the curve I. obtained with soot- 

 covered electrode. This is explained to be due to the emission 

 of some /3 rays, when the Rontgen rays hit the electrometer 

 electrode. 



The other effect caused by Rontgen rays will be considered 

 in the discussion of the final results (§ 9). 



§8. The Results, ' The Distribution of the Velocities 

 of the Secondary Cathode Rays. 



The results obtained for air are tabulated in Table I., the 

 values of the potential differences applied to the gauzes 

 being V 1= -12 volts, V 2 =-2 volts, and V 3 =-12— v 

 volts. The first column gives the values of v representing 

 the variable retarding fields for the secondary cathode rays. 

 These results are calculated by noting the number of second- 

 ary cells used, each cell being considered to have a potential 

 difference of 2 volts. The kinetic energies of the primary 

 cathode rays are written in volts in the first row. The 

 figures in each column (in the second row and below) are 

 the currents representing the relative numbers of the second- 

 ary cathode rays which have velocities greater than v volts 

 in the corresponding rows. 



As the table shows, the currents decrease very rapidly 

 with increase of v up to 40 volts, then slowly, and after 

 i<=900 volts they become almost constant and small, though 

 not negligibly so. The currents observed in the case of the 

 primary rays with a velocity of 10,500 volts are plotted in 

 curve II., fig. 5, where the abscissae indicate the values of 

 v in volts. 



