110 Prof. E. Rutherford on Uranium Radiation and 



polarization or refraction have been obtained for Rontgen 

 radiation. 



It is the object of the present paper to investigate in more 

 detail the nature of uranium radiation and the electrical 

 conduction produced. As most of the results obtained have 

 been interpreted on the ionization-theory of gases which was 

 introduced to explain the electrical conduction produced by 

 Rontgen radiation, a brief account is given of the theory and 

 the results to which it leads. 



In the course of the investigation, the following subjects 

 have been considered: — 



§ 1. Comparison of methods of investigation. 



§ 2. Refraction and polarization of uranium radiation. 



§ 3. Theory of ionization of gases. 



§ 4. Complexity of uranium radiation. 



§ 5. Comparison of the radiation from uranium and its 

 compounds. 



§ 6. Opacity of substances for the radiation. 



§ 7. Thorium radiation. 



§ 8. Absorption of radiation by gases. 



§ 9. Variation of absorption with pressure. 

 § 10. Effect of pressure of the gas on the rate of discharge. 

 § 11. The conductivity produced in gases by complete 



absorption of the radiation. 

 § 12. Variation of the rate of discharge with distance 



between the plates. 

 § 13. Rate of re-combination of the ions. 

 § 14. Velocity of the ions. 

 § 15. Fall of potential between two plates. 

 § 16. Relation between the current through the gas and 



electromotive force applied. 

 § 17. Production of charged gases by separation of the ions. 

 § 18. Discharging power of fine gauzes. 

 § 19. General remarks. 



§ 1. Comparison of Methods of Investigation. 



The properties of uranium radiation may be investigated 

 by two methods, one depending on the action on a photo- 

 graphic plate and the other on the discharge of electrification. 

 The photographic method is very slow and tedious, and admits 

 of only the roughest measurements. Two or three days' 

 exposure to the radiation is generally required to produce any 

 marked effect on the photographic plate. In addition, when 

 we are dealing with very slight photographic action, the 



