|Vacuum tube with mercury.|
I have no idea why this vacuum tube contains beads of mercury. If it gets hot in operation that mercury will vaporize and create a gas much better able to sustain an arc than is vacuum. That is the function of mercury in arc lamps, and presumably that is what it's here for as well.
Source: Max Cane
Contributor: Max Cane
Acquired: 11 August, 2007
Text Updated: 3 September, 2007