Narration

The actual apparatus consists of a condenser with the high-voltage coil of wire on the inside and the grounded coil of wire wrapped around the outside. The oxygen gas passes through the part of the condenser that would contain water if the condenser were used in the normal way. Since both ozone and oxygen are invisible, a small feather has been placed over the exit tube so that an escaping stream of gas will cause it to move. The Tesla coil is turned on. When the oxygen is turned on, in normal light, the feather can be seen to move, but there is no visible gas. A small plate of glass has been hung above the exit tube. Since the glass is transparent to visible light, it casts no shadow.