Kathy Zipp, a New York resident and former chemistry teacher, has taught other teachers how to perform this common experiment. She said it demonstrates several scientific principles, including what elements are needed to create an explosion and how chemical energy can be converted into motion. The experiment involves a small plastic jug with two nails driven into its sides. The pointed ends of the nails face each other but don't quite touch. The teacher pours a small amount of methanol into the jug, puts a cork on the jug, and shakes the jug, she said.
Methanol vaporizes quickly and the jug gets filled with the vapor.
The teacher removes the cork and pours the remaining methanol out of the jug. The teacher then puts the cork back on and clamps the jug down sideways, so the nails are pointing up and down and the cork is pointing to the side. An electric coil attached to one of the nails creates a spark that jumps between them, igniting the vapor. The combustion causes the vapor to expand and blows the cork off the jug. It's common to repeat the experiment to show it can't happen again, Zipp said.