Liquid Mercury vortex in a magnetic field

In this experiment we see that half of a copper globe is anodized with nickel metallic paint and connected to an electric wire in a direct current pole. In the center of the container there is a brass bolt electrically isolated from the container and connected to another pole of the direct current. At the base of the wooden support there is a large magnet which generates a magnetic attraction. Liquid mercury weighing just over 1 kg is poured into the container. When current flows through the two conductors, it generates a strong magnetic field that supports the system. This favorable condition causes mercury to rotate since it is a very conductive metal. For the success of the experiment it is necessary to have liquid mercury not less than 1 kg. The experiment does not work with gallium, as it is a less fluid metal. The voltage source is given by a 2 volts 45 amps transformer driven by a direct current inverter. The current absorbed for operation is approximately 38 amps. The speed of rotation of the mercury varies according to the weight and the voltage supplied. System doesn't work in alternating current.