L 202 J 



XXI. On the Velocity of Secondary Cathode Rays emitted by 

 a Gas under the Action of High-Speed Cathode Rays. 

 By M. Ishino, Rigakushi, of the Imperial University of 

 Kyoto, Japan *. 



Contents. 

 § 1. Introduction. 

 § '2. Apparatus. 

 § 3. Experimental Procedure. 

 § 4. Experiments on the Positive Ions. 

 § 5. Experiments on the Action of the Metallic Gauzes. 

 § 6. Arrangement of the P.D. between the Gauzes. 

 § 7. Effect due to Pontgen Pays. 

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



the Secondary Pays. 

 § 9. Examination of the Residual Currents. 

 § 10. General Conclusions. Summary. 



§ 1. Introduction. 



THE ionization of various substances in different states- 

 has been investigated by many observers. The initial 

 velocity of the particles during ionization may have an 

 important bearing on the theory of ionization and on that of 

 the structure of the atom. Lenard f was the first to esti- 

 mate the velocity of the secondary cathode rays from a 

 metal. The metal was bombarded by slow cathode rays, 

 produced by the action of ultra-violet light on a metallic 

 plate. He observed that the greater proportion of the 

 secondary cathode rays left the metal with velocities less- 

 than "that acquired by the corpuscle under a fall of potential 

 of 11 volts " (or merely for brevity "a velocity of 11 volts"), 

 v. Baeyer}, Grehrts § ; and Campbell || and others investi- 

 gated the same problem. They used a retarding electric 

 field to determine the velocity of the secondary cathode 

 rays, i. e. so-called 8 rays. The results showed that the 

 velocity of the 8 rays depended upon the velocity or the 

 kinetic energy of the primary rays, provided that the kinetic 

 energy was not large ; but that the velocity did not depend 

 very much on the kind of metal from which 8 rays were 

 liberated. They have shown that the greatest velocity of 

 the 8 rays did not exceed 30 volts, notwithstanding the fact 

 that different velocities of the primary rays were used. 



For the case of primary rays having very high speeds of 



* Communicated by Sir J. J. Thomson, O.M., F.P.S. 

 t Lenard, Ann. d. Phys. xii. p. 449 (1903). 

 j v. Baever, Phys. Zeits. x. p. 176 (1909). 

 § Gehrts, Ann. d. Phys. xxxvi. p. 995 (1911). 

 || Campbell, Phil. Mag. xxv. p. 803 (1913). 



