How is barometric light porduced? A shaken sealed glass tube containing liquid mercury in a dark room will glow.  This has been know since the 17th century and is called barometric light.  How does the addition of potassium  permanganate crystals to the mercury influence the production of light?
 A: You can actually observe barometric light if you have access to one of those old pen-style mercury arc lamps. Turn it on, let it run for 5 minutes (and wear the necessary eye protection), and then turn it off. Then, in a dark room, rub the hot glass tube up and down with a piece of cloth.
You will observe flashes of purple light as you run your hand up and down the glass. This is barometric light.
Unfortunately, I don't have my mercury lamp on hand so I don't have a picture of the phenomenon, so here is a surrogate photo of a typical mercury pen lamp:

The phenomenon was actually investigated by Francis Hauksbee in the late 1600's; incidentally, Hauskbee is the same guy who was behind the Hauksbee electrostatic machine, which presumably works for a similar principle. 
The flashes are due to static discharges, which the mercury converts into light.
As for how potassium permanganate would affect the phenomenon, I have no idea; I have mild acid burns on my hands from a potassium permanganate hypergolic explosion from a few years ago, so the idea of mixing two deadly compounds (like mercury and a permanganate) seems like a bad idea, to put it mildly.
