Mercury Vortex in a Magnetic Field

Neat demonstration.

I believe Faradays first motor was a magnet and wire suspended over a cup of mercury to act as a conductor.

There is also a telescope that uses a spinning vat of mercury to form a reflector.

Vintage mercury vapor rectifiers are really neat to watch.

https://youtu.be/5ftCS5wwiPY

Had fun playing with mercury as a kid; say what you will. Still have my 1 pound container of it.