Diffusion Cells in Ionized Gases. 499 



used. With gypsum this constant was found to be 7*621 . 10~ 8 

 cm., being- the mean of two determinations only differing 

 by 0*16 per cent. 



The values of the wave-lengths are put together in 

 Table I., and in Plate XI. a graphical representation of the 

 results (from zirconium to uranium) after the relation of 

 Moseley is given. As seen, 14 line-groups seem to be sure 

 in the L-series. Of these tha /-group was discovered by 

 Siegbahn *, who has examined the.se lines in the elements 

 tungsten-uranium. The graphical representation shows 

 further, that only in some cases (a 2 , a 1? /9 2 ) a Moseley relation 

 holds good for the whole range, while the other groups 

 generally form curves slightly convex to the X-axis. The 

 order of the rare earths here found agrees with that generally 

 adopted. The order Te-I found by Siegbahn f for the 

 K-series is also verified here. 



I have much pleasure in recording my thanks to Dr. M. 

 Siegbahn for suggesting this work to me. 



Physical Laboratory, University of Lund, 

 June 191(5. 



LIV. Diffusion Cells in Ionized Gases. By E. B. AVoOD, 

 21. A., 0. A. de Long, B.S., and K. T. Oompton, Ph.D.> 

 Assistant Professor of Physics ? Princeton University %. 



IN a recent paper § Mr. W. H. Jenkinson has shown 

 very conclusively that an electromotive force is set up 

 between two similar electrodes in a o-as if the degree of 

 ionization of the gas surrounding the two electrodes is 

 unequal. The effect of this phenomenon on the relative 

 potentials of an electrode and the surrounding gas had 

 already been investigated by Professor John Zeleny||. The 

 interpretation given by Mr. Jenkinson to his results, however, 

 appears to us deserving of further examination. 



Following the analogy of Nernst's treatment of electro- 

 lytic cells by the concept of solution tension and solution 



* Verh. d. Phys. Ges. xviii. p. 150 (1916). 

 t Verh. d. Phys. Ges. xviii. p. 39 (1916). 

 \ Communicated by the Authors. 



^"Concentration Cells in Ionized Gases," Phil. Mag. xxviii. p. G85- 

 (1914). 



|| Phil. Mag. xlvi. p. L34 (1898). 



