Distribution of Energy in the Spectra of Gases. 475 



Drs. Pohl and Pringsheim have found that the long wave- 

 length limit of the photo-electric effect for some of the 

 metallic surfaces prepared by them shifts a considerable dis- 

 tance along the spectrum during the course of a few hours 

 after the formation of the surface. This interesting result 

 does not tell us anything about the relation between V and 

 n ; all that it does is to show that V in equation (1) pro- 

 bably alters with the course of time. It is probable that if 

 they measured the emission velocity of the photo-electrons 

 while the surfaces of the metals were changing, they would 

 find that the relation between the velocity and the frequency 

 was always represented by (1) and that the line corresponding 

 to (1) moved parallel to itself as the long wave-length limit 

 moved towards the red end of the spectrum. This is a point 

 to be decided by experiment. 



Yours truly, 



A. Ll. Hughes. 

 The Rice Institute, 



Houston, Texas. 



Dec. 24th, 1913. 



LY. On the Distribution of Energy in the Spectra of Gases. 



To the Editors of the Philosophical Magazine. 

 Gentlemen, — 



IN Mr. H. L. P. Jolly's paper on the Distribution of 

 Energy in the Spectra of Gases in the Philosophical 

 Magazine for November 1913, there is to be found a summary 

 of previous work on the subject, from which several papers 

 published by myself or pupils of mine on the same subject 

 .are missing. May I be allowed to mention those papers for 

 the benefit of the readers of your Journal : — 



H. Konen and W. Jungjohann, " Studies on the Emission 

 of Gases," Astrophys. Journ. xxxi. pp. 404-418 (1910). 

 H. Konen and W. Jungjohann, " Studies on the Emission of 

 Gases, II.," ib. xxxii. pp. 141-152 (1910). W, Jungjohann, 

 a Ueber Emission und Absorption leuchtender Gase bei 

 hohen Stromdichten unter Yerwendung von Gleichstrom/' 

 Zeitschr. f wiss. Photographie Sfc, ix. pp. 84-103, 105-lb*8 

 (1910). H. Kyll, " Intensitatsmessungen im positiven 

 Bandenspectrum des Stickstoffs," Dissertation, Minister, 1910. 

 J. Schwedes, " [Jeber Intensitatsmessungen stromender Gase 

 bei hohen Stromdichten unter Yerwendung von Gleichstrom," 

 Zeitschr. f. wiss. Photographie S(c. xi. pp. 169-204 (1912). 



