[theThinker (OP)]

Google search will lead to the passage in "Newtonian Electrodynamics" which explains this experiment. It is associated with verifying if there is any Ampere's longitudinal forces between collinear elements in a conducting wire.

There are two electrodes connected to a high voltage DC source. One is a vertical copper rod bar; above this is a horizontally placed copper circular ring electrode of much larger radius. The electrodes are placed in a dielectric (insulator) container of mercury just covering the ring. When a DC source is connected to the electrodes, a  high current flows in the mercury. A mercury fountain will form with the mercury pushing up the middle of the ring and bulging up, overflowing back to the side of the ring.

I find it strange that the experimenter, Peter Graneau, did not mention if the mercury fountain will form independent of current direction. My understanding is that such experiments are usually current direction independent; it should work even with AC source. But I prefer a real confirmation. My google search finds nothing.

Anyone here "knows" the answer? Or better in doing a google search?
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