> There are also mercury arc rectifiers but you probably don't want to get =
into
> that kind of thing- they can contain enough mercury to keep a hazmat team
> busy for some time.

Oh, so shades of when I was a lab boy at secondary school, and asked to set=
 up an experiment to show the magnetic field around wires.

A couple of test tube stands, some lengths of 16AWG wire, a dish with about=
 a pint of mercury open to the air, and a 6V motor bike battery as  power s=
ource IIRC. Hang wires from stand so bottom end is sitting in mercury. Conn=
ect one side of battery to stand, wire from other battery terminal held in =
hand and stripped end dipped into mercury when needing to 'turn on the curr=
ent'. Gave an impressive demonstration of how the wires attracted when the =
current through them was running the same way, and repelled when the curren=
t was down one and up the other.=20

A bit of mercury vapour from the arc when the wire went in and came out of =
the mercury? Who cares, we are just a classroom full of secondary school ki=
ds ... couldn't do it these days H&S would have a field day.

Topic changed again.



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