A Smokin' example of Charles's Law! Using the Fire Syringe to compress air into a smaller volume is a classic example of how rapidly doing work on a gas results in an increase in temperature. Once you have inserted a small piece of combustible cotton fiber into the syringe piston, a quick firm stroke on the piston handle produces a flash in the chamber which burns as long as there is air present. The Fire Syringe comes with combustible fiber, and 2 replacement O-rings for the piston.