On the Complete Emission Function. 379 



oxygen is set free from commercial aluminium and 

 magnesium. 



5. Certain carbon bands are always present in glass tubes 

 filled with hydrogen, nitrogen, oxygen, and ammonia 

 gas, notwithstanding the greatest care which may have 

 been taken in submitting them to a high temperature 

 during the process of exhausting, when powerful dis- 

 charges are employed. 



6. The brilliancy of the light of tubes filled with hydrogen 

 diminishes as the process of the dissociation of water- 

 vapour goes on and the resistance of the tube increases. 

 It is possible to raise such a tube to the a*- ray stage from 

 a pressure of 1-2 mm. merely by the application of a 

 strong steady current. 



7. The 07-rays excited by the application of a steady 

 current are due to the radiations set up by the dissocia- 

 tion of highly rarefied water-vapour. 



Jefferson Physical Laboratory, 

 Harvard University, Carnb., U.S.A. 



XXXVIII. On the Complete Emission Function. 

 By P. G. Nutting* 



THE relation between emission, temperature, and wave- 

 length, developed theoretically by Wienf and by 

 Planck J, and empirically by Pascheu §, expresses the amount 

 of the radiation from a black or perfect radiator, in regions 

 of temperature and period in which the emission-period 

 function is continuous- Von Kovesligbety || has given a 

 function by which the emission of a limited class of substances 

 may be represented in the optical region. By means of the 

 modern theory of functions, a function more general than 

 either may be developed ; expressing the emission of all wave- 

 periods, of both complete and partial radiators, as well in the 

 lined as in the banded and continuous spectra. The Wien 

 formula will be developed by the same method, as a preliminary 

 step in the development of the complete function. 



The intensity of the emission from a body, being a function 

 of the entirely independent arguments, temperature and 

 wave-period, we may construct each function separately and 



* Communicated by the Author. 

 f W. Wien, Wied. Ami. lviii. p. 6G2 (1396). 

 X M. Planck, Bed. Berichte, Mav 1899. 

 § F. Pasclien, Wied. Ann. lviii. p. 491 (18961 



|| R. v. Kovesligbety, Astr. Nachr. No. 2805, cxvii. p. 330 (1887) ; 

 Math, u. XaLBeric/iJe Unyarn, xvi. p. 40 (1899) ; Beibl 1900, p. 1280. 



