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XLVIII. The Spectrum of Hydrogen Positive Bays. By 

 L. Vegard, Dr.Philos. and Professor of Physics at the 

 University of Christiania *. 



IN the number of the Philosophical Magazine for August 

 1920, Mr. G. P. Thomson has published some results of 

 investigations with regard to the light produced by positive 

 rays in hydrogen. 



He has studied the light emission of positive rays of 

 a different composition, and according to his interpretation 

 of the results the positive rays themselves in the molecular 

 form should emit the so-called second or many-lined 

 spectrum of hydrogen. This would mean that the second 

 spectrum should show a Doppler effect — a result which is 

 opposed to all evidence so far as yet obtained. 



In spite of a great many searches for such an effect by 

 Stark t. Wilsar J, Rau, and the author under very varied 

 conditions, it 1 as not been found. Under these circum- 

 stances it seems that the indirect evidence given by the 

 experiments of Mr. Thomson is by no means conclusive, 

 and it is my intention to direct the attention to certain 

 facts which may give an interpretation of Thomson's ex- 

 periments without assuming that the positive rays themselves 

 emit the second hydrogen spectrum. 



In a series of papers published in Ann. dec Physik from 

 the year 1912 to 1917 § I have given results of investi- 

 gations with regard to the laws governing the light-emission 

 of positive rays, and I shall briefly mention some results that 

 have a bearing on the present question : — 



(1) The second spectrum of hydrogen is part of the 



"unmoved" spectrum of the positive rays, and 

 the intensity of the lines of the second spectrum 

 increases in the same rate as the unmoved spectrum 

 of the series lines. 



(2) The ratio between the intensity of Hie moved and 



unmoved spectrum was found to vary very greatly 

 with the velocity of the rays and with the pressure 

 in the observation chamber. 



Thus when the potential varied from 8500 to 27,000 volts, 

 the ratio between the moved and unmoved intensity of H^ 



* Communicated by the Author. 

 t J. Stark, Ann. d. Phys. vol. xxi. p. 425 (1900). 

 % H. "Wilsar, Ann. d. Phys. vol. xxxix. p. 1251 (1912). 

 § L. Yegard, Ann. d. Phys. vol. xxxix. p. Ill (1912) ; vol. xl. p. 711 

 (1913) : vol. xli. p. 625 (1913) ; vol. Hi. p. 72 (1917). 



