﻿1128 Prof. M. N. Saha on Temperature Ionization of 



Wilson *, and on rosin, sulphur, and ebonite in the interval 

 1902-8 by the author f. 

 From Maxwell's theorem 



Adding together the expressions for Pj and P 2 we obtain 

 very simply the expression for P given above as hitherto 

 derived only on the basis of the Cohn-Minkowski equations J. 



The Carnegie Institution 



of Washington, 

 Department of Terrestrial Magnetism, 

 April, 1922. 



CIV. On the Temperature Ionization of Elements of the 

 higher Groups in the Periodic Classification. By Megh 

 Nad Saha, D.Sc, F.I. P., Guruprosatt Sinylia Professor 

 of Physics , University of Calcutta, India §. 



I. 



THE theory of the temperature ionization of gases and its 

 application to problems of radiation and astrophysics 

 was given by the present writer in a number of papers 

 published during last year. In these papers the theory was 

 limited to the ionization of gas consisting of atoms of a 



* H. A. Wilson, Roy. Soc. Phil, Trans. A. 1904, p. 121. Wilson con- 

 sidered his experiments to prove that the motional electric intensity or 

 electromotive force was proportional to (K — 1), which is not correct. 

 According to all theories, the motional intensity is independent of the 



medium and equal to - [uB] ; while on the theory of Larmor and 



Lorentz, the resulting polarization is proportional to (K — 1), the result 

 s-upported by the experiments. 



t S. J. Barnett, Phys. Rev. xxvii.p. 425 (1908). 



| The permeability fi differs from unity so slightly for all insulators 

 that it is impossible at present to distinguish experimentally between P 

 and Pi. By embedding a large number of small steel spheres in wax, 

 however, M. Wilson and H. A. Wilson (Proc. Roy. Soc. A. lxxxix. 

 p. 99 (1914)) formed a composite dielectric whose mean permeability, for 

 large volumes, was much greater than unity. On the assumption that 

 this procedure is justifiable, the results of experiments which they made 

 on the electric effect of moving the composite substance in a magnetic 

 field support the above equation for P. M. and II. A. Wilson concluded 

 that their results therefore supported the (Einstein-Minkowski) principle 

 of relativity. As shown in §17, however, the result follows from 

 Maxwell's theorem based on a much older, though less exact, relativity 

 principle. 



§ Communicated by the Author. 



