728 
The so-called cyanogen-bands have completely disappeared; it 
follows that these bands do not belong to nitrogen, but to a much 
more easily condensable substance, probably cyanogen. ') 
This is in accordance with Steusine’s observations; the latter found 
no trace of the cyanogenbands in his experiments, where the presence 
of any carbon was excluded. *) 
Probably Grotrian and Runae's nitrogen was not completely free 
from carbon. This may be due to the fact that they purified their 
nitrogen by pyrogallicacid-solution; during this operation small 
quantities of carbon monoxide are usually developed. 
Eindhoven. Laboratory Philips’ Incandescent 
Lamp works Ltd. 
1) In some of our experiments we completely immersed the discharge-tube in 
liquid oxygen, the spectrogram being taken through the walls of the Dewarvessel. 
During the operation of the Tesla transformer the walls of the Dewarglass show 
the green fluorescence of cathode-rays. In one of our experiments however some 
gas was liberated in the space between the walls of the Dewarvessel, so that a 
red glow appeared, the radiation of which is superposed on that of the discharge- 
tube. The so-obtained spectrogram is shown in fig. 3. A peculiar phenomenon may 
be observed. Some of the cyanogen-bands, namely 3855, 3883 and 4168 A. come 
out very strongly, whereas the other ones are absent. So it is not impossible. 
that the cyanogen-bands are due to two different carriers. 
*) Simular results have been obtained by L. HAMBURGER, who also found no 
trace of the cyanogenbands in extremely pure nitrogen. Chem. Weekblad (15) 931 
1918. (Added in translation). 
