Today’s scientific fact may become tomorrow’s scientific myth.
In 1667, for instance, the German alchemist, Johann Becher, proposed the theory that substances that burned in air were rich in “phlogiston,” and when they combusted, they released this element into the air. In the process, they lost mass.
That notion held sway for about a century.
But if metals gave off their phlogiston during their combustion, should they not lose weight, later research questioned? It couldn’t explain why a metal gained mass, when it burned (which happened, of course, because it combined with the oxygen in the air to form an oxide.)
It were the experiments of Antoine Lavoisier, a French civil servant and chemist, which dismantled it. He demonstrated that combustion needed a gas, a gas called oxygen.