Mix 2/3rds of Joy liquid with 1/3rd glycerin to make soap bubbles.
Put some of the mix into a dishwashing pan of warm water.
Bubble propane gas through the soapy water.
Remove the propane gas and light the bubbles with a fireplace match or a burning torch. Some soot will be produced. A propane torch can be purchased at a hardware store.
Caution: if you use oxy-acetylene with both gases on you could damage your hearing.
