Narva Hg/E 2 40W (HQE40) High pressure spectral lamp

This lamp originally developed by Osram in the 1930s as laboratory light source. It consist of a tubular outer envelope which fins to towards the end mad from soda-lime glass. This limits the transistion at around 280nm. Should even lower wavelength light be desired a hole would be melted in the side of the lamp.
The early lamps of this design like this one feature vacuum shrunk arc tube seals instead of the more common pinch seal design. It is believed that this design was used longer with Narva than with Osram. Also Narva developed in the 70s a revised version of this lamp, featuring a pinch sealed arc tube with platinum heat reflective coating at the end and novel toroidal shaped starcing electrodes, minimizing the effect of glowing red electrodes on the lamps spectrum.

This lamps runs at 40W, .5A and 85-115V making it rather similar to american H45 lamps.