The performer displays a test tube in his hand, which has been closed with a cork. Inside the tube rests a solid silver bar.
With a gesture from the performer, the silver bar begins to bob up and down inside the closed tube, banging against the cork.
Eventually, the bar pops the cork off of the tube! Then, the silver bar rises up out of the tube and floats about in mid-air!
Finally, the bar floats back into the tube. The magician sets the cork back in place and receives a well-deserved round of applause.