Physics. — ''On (he light emission oj gases and inivlures of gases 

 by electric discharges" By Dr. L. Hamburger. (Communicated 

 by Prof. H. Kamerlingh Onnes.) 



(Communicated in the meeting of December 29, 1917). 



§ J. Method of investigation. 



Researches on the influence of different factors in the emission of 

 light of gases by electric discharges have revealed phenomena of so 

 very different nature, that we strongly felt the desirability of system- 

 atic methods of investigation and of objective measuring methods 

 that are free from the imperfections of the human eye. 



As however in spectroscopy and the measuring of intensities which 

 is closely connected with it, great difïiculties arise, we should have 

 to wait a very long time for results if we wished to measure the 

 intensities of each emitted wavelength (spectral line or band) for 

 the different gases and mixtures and then still under different cir- 

 cumstances. Therefore on entering this difficult and vast domain of 

 research our first work can only be a first exploration of the new 

 field of investigation, which work renders a method desirable which 

 allows a quick survey of what is observed under different conditions. 

 Such a method is the photographic one, which can also be used in 

 the ultraviolet part of the spectrum and which has been described 

 in a recent publication of G. Holst and L. Hamburger. ^) 



In the two next paragraphs of this short paper a survey is given 

 of the most important results of an investigation made in this way 

 on the influence of different factors on the emission of light of gases 

 and mixtures by electric discharges. The lightning of the gases was 

 excited by a continuous current discharge apparatus the construction 

 of which is based upon the direction lines determined by H. Konen 

 and W. JuNGJOHANN ') and in which (comp. J. Sohwedes')) streaming 

 gases are used. By the application of streaming gases several pheno- 

 mena could be investigated which up til! now had not or hardly 

 been observed. 



The sector method alone, described in the publication of G. Holst 



1) These Proceedings, p. 1021. 



5) Verb. d. D. phys. Ges. (12) 8, 128—144 (1910). 



^) Zeitschr. f. wiss. Phot. 11, 199 (1913). 



