On Excited Radioactivity and its Transmission. 95 



(5) The value of n is probably 05 for monatomic gases, 

 and 1*5 for diatomic gases, on the simple hypothesis of 

 integral degrees of freedom. These values give very fair 

 agreement with experiment, but there is no a priori reason 

 why the number of degrees of freedom should be an integer 

 for a polyatomic molecule. 



(6) The properties of C0 2 at moderate pressures are well 

 represented by the assumption n = 2, provided that account 

 is taken of the variation of the specific heat as observed by 

 Regnault. This reconciles the hitherto discordant results for 

 the cooling-effect and the compressibility. 



(7) The properties of Steam, including the variation of the 

 latent heat and the saturation-pressure, are well represented 

 by the value n = 3*3, if the limiting value of the specific 

 heat at zero pressure is assumed to be independent of the 

 temperature, provided that the variation with pressure is 

 not neglected. 



(8) The value of the Absolute Zero, as deduced from the 

 pressure-coefficient of hydrogen, is probably within one or 

 two hundredths of a degree of 273 o, 10. 



IV. Excited Radioactivity and the Method of its Transmission. 

 By E. Rutherfokd, M.A., JD.Sc, Macdonald Professor of 

 Physics, McGill University, Montreal*. 



§ 1. Introduction. 



§ 2. Connexion between the excited activity and the emanations. 



§ 8. Method of transmission of excited activity. 



§ 4. Velocity of carriers of thorium-excited activity. 



§ 5. Increase of excited radiation with time. 



§ 6. Radium-excited activity. 



§ 7. Distribution of excited activity on the anode. 



§ 8. Velocity of the carriers. 



§ 9. Origin of the carriers. 



§ 10. Nature of the radiations. 



§ 11. Evidence of chemical changes. 



§ 12. Summary of results. 



§ 1. — Introduction. 



ONE of the most interesting properties of the radioactive 

 substances thorium and radium, is their power of com- 

 municating or exciting f temporary radioactivity to all bodies 

 in their neighbourhood. If a wire charged to a high negative 



* Communicated by the Author. Preliminary accounts of these 

 results were communicated to the American Phvsical Society, New York, 

 December 27, 1901. and to Phys. Zeit. No. 10, i902. 



f (Note) — The term " excited," has been used throughout these investi- 

 gations rather than " ^nduced, ,, which has found favour with main 



