476 Prof. 0. W. Richardson on the Theory of 



H. Konen, '"das Leuchten der Gase und D'ampfe," Braun- 

 schweig, 1913, pp. 302 ff. Besides many papers by other 

 authors not mentioned in Mr. Jolly's summary. 



From the experience gained in our Miinster Laboratory 

 it seems necessary : 



(1) to make use of tubes with a continuous flow of gas; 



(2) to make use of continuous electric current in all mea- 

 surements of intensity or energy of spectral lines in order 

 to avoid complications that make it impossible to draw any 

 reliable conclusions either from radiometric or photometric 

 measurements. That it is possible to fulfil both conditions, 

 by means of special tubes described in the first of the papers 

 mentioned above, is^ in my opinion, conclusively shown by 

 Mr. J. Schwedes. 



Yours very truly, 



H. Konen. 



Minister i/W, physikalisclies Institut 

 der Universitat, Jan. 25, 1914. 



LVI. The Theory of Photoelectric and Photochemical Action. 

 By 0. W. Richardson, F.R.S., Wheatstone Professor of 

 Physics, University of London, King's College*. 



FOR many reasons and especially on account of the 

 complexity which recent experimental investigations f 

 have shown to characterize the relation between the number 

 of electrons emitted by bodies and the intensity and frequency 

 of the radiation used to stimulate them, it seems desirable to 

 consider the theory of these effects from as many points of 

 view as possible. I have therefore amplified the discussion 

 of some of the points raised in my previous papers dealing 

 with these questions. I shall consider first the amount of 

 energy which is abstracted from the radiation when one 

 electron or atom is liberated. In what follows immediately 

 I shall use the term atom to include electrically charged 

 particles, i. e. ions and electrons, since the argument is exactly 

 the same whether the particles are supposed electrically 

 charged or not. 



* Communicated by the Author. A paper read before the American 

 Physical Society at the Chicago Meeting-, Nov. 28, 1913. 



t Pohl and Pringsheim, numerous papers in recent volumes of the 

 Verhandlungen der Deutschen Physik. Gesellschaft. Compton and 

 Richardson Phil. Mag. vol. xxvi. p. 549 (1913). 



