Physics. — “The so-called cyanogen-bands’. By G. Horsr and 
E. Oostersuis. (Communicated by Prof. H. KAMERLINGH ONNes). 
(Communicated at the meeting of May 29, 1920). 
In photographing the nitrogen-spectrum one usually observes a 
number of bands, which were formerly ascribed to cyanogen’). 
The most prominent of these bands lie between 3855 and 3883 A. 
and between 4158 and 4216 A. In 1914 Grorrian and RUNGE?) 
made some experiments, from which they concluded, that these 
bands are due to nitrogen and should not be ascribed to cyanogen. 
Many later observers’) have considered this view to be the right one. 
We have made a new investigation on this point and came to 
the conclusion that these bands are not due to nitrogen, but to one 
of its compounds which condenses at a much higher temperature. 
In our experiment the discharge tube was a cylindrical glass tube 
with one electrode connected to a Tesla-transformator. The gas in 
: the tube was an argon-nitrogen- 
mixture containing about 15°/, 
of nitrogen. The gaspressure was 
1. about 55 cm. Under these cir- 
cumstances the spectrum shows 
no argon lines, only the nitro- 
2. genbands and the so-called 
“cyanogen-bands”. (Fig. 1). 
The bands 3855—3883 A 
3, can be seen at A, the bands 
4158—4216 A at B. 
In order to discriminate 
whether these bands are due to 
nitrogen or to cyanogen, we immerged the lower half of the discharge 
tube into a glass filled with liquid oxygen and so obtained the 
spectrum fig. 2. 
AEB, 
U See Kayser, Handbuch der Spectroskopie. Bd. 5. 
2) W. Grotrian and C. Runee. Phys. Z. S. 15, 545. 1914. 
8) W. Sreusine. Phys. Z. S. 20, 512. 1919. 
L. Greet und A. Bacuem. Verh. D. Phys. Ges. 21, 454. 1919 and Zeitsehr. f. 
Physik, 1, 51. 1920. 
