Geissler tube

This is another old Geissler tube I have and think it would have been made for educational purposes as it is of a simple construction when compared to more ornate varieties. The tube appears to have some uranium content as can be seen when viewed under blacklight. The top right image shows one of the electrodes and cap.

As the arc forms a thin line it is easy to noticeably influence it with a magnetic field, shown in the middle of the montage. This suggests the pressure is quite high. The tube requires over 3kV to strike but runs with 2kV.

I was also trying to capture the spectrum to determine the gas used, however the light output is quite low for my spectrometer arrangement. I initially though argon but from the image obtained and shown bottom right I suspect Nitrogen or just air, as was common with Geissler tubes.