I was recently reading about the mercury Sprengel pump, which, until the arrival of the diffusion pump, created the highest vacuum possible. Several references to the Sprengel pump mention the periodic flashes of light in the high vacuum vessel, during the pumping process....but no explanations are ever given for this. Does anyone have any information on this?

Eric

 

I was recently reading about the mercury Sprengel pump, which, until the arrival of the diffusion pump, created the highest vacuum possible. Several references to the Sprengel pump mention the periodic flashes of light in the high vacuum vessel, during the pumping process....but no explanations are ever given for this. Does anyone have any information on this?

Eric

I would guess that glass holds electric charge very well and the Mercury falling through the glass tube can act like a silk cloth rubbing the glass and creating a static charge on the surface of the glass. The Mercury does conduct and can dissipate charge but, in the case of this vacuum pump, the beads of mercury are separated by the residual gas pulled from the bulb and, therefore, cannot form a continuous connection and, I would assume, the flash occurs either as 1) a bead of mercury passes by a specific point where charge was deposited on the glass from a previous bead, or, 2) as the bead comes in contact with the resivoir at the bottom. I would guess option 1 is more likely.

 

I would guess that glass holds electric charge very well and the Mercury falling through the glass tube can act like a silk cloth rubbing the glass and creating a static charge on the surface of the glass. The Mercury does conduct and can dissipate charge but, in the case of this vacuum pump, the beads of mercury are separated by the residual gas pulled from the bulb and, therefore, cannot form a continuous connection and, I would assume, the flash occurs either as 1) a bead of mercury passes by a specific point where charge was deposited on the glass from a previous bead, or, 2) as the bead comes in contact with the resivoir at the bottom. I would guess option 1 is more likely.

That sounds reasonable, though the only way to test it is to build one and see. I don't think the wifeypoo would appreciate me playing with a few quarts of mercury on her kitchen counter though. *-^

 

That sounds reasonable, though the only way to test it is to build one and see. I don't think the wifeypoo would appreciate me playing with a few quarts of mercury on her kitchen counter though. *-^

Yeah, You are in North Pole, AK. Getting sent to the dog house would be hella cold. Let's see if some guy in Russia posted a YouTube video of it.