Sadly, the school Science Fair is probably cancelled this year, but that doesn’t mean Junior can’t enjoy some exciting science experiments at home, such as the ones described 80 years ago this month in the April 1940 issue of Popular Science.

Actually, it might be a good thing that the official Science Fair is cancelled. It’s unlikely that the science teacher would sign off on these experiments, since they amount to playing with fire, and it would be hard to tie them in to the scientific method of inquiry. But they do have a redeeming scientific value of getting Junior excited about science, and they look like fun, as long as they are done in the backyard far away from any combustible objects.

The best experiment is shown above, where a line is traced out and then used as a racetrack for a race of fire.  A “pinch or so” of potassium nitrate (also known as saltpeter) is dissolved in a teaspoon of water.  This is used as ink, and the race course traced on a piece of paper.  When the paper is dried, the starting line is ignited with a “lighted match or cigarette tip.”  (Due to a pandemic of respiratory illness in progress, we advise against using a cigarette.)  Trails of fire then appear, racing to the finish line.  You can order the potassium nitrate at Amazon.