The Discovery of Oxygen, by Caleb

On August 1st 1774 Priestly put calx of Mercury underneath a glass and it began to give off a gas. The gas was oxygen. Well, this gas was very flammable and he wondered if it was poison so he took a jar and filled it with air then he took another jar with this gas and put a mouse in each one. The mouse with the weird gas lived for 30 minutes but the one with normal air lived half that long. The air we breathe is only 20% oxygen.

Mr Priestly was saying that the reason that when you put a candle in a jar and it goes out is because it puts off phlogiston, but really it just uses up the oxygen.

Later, Lavoisier did an experiment that proved it was burning up all the oxygen, and not really just filling the jar with phlogiston.

Priestly discovered the mysterious unknown gas, but Lavoisier is the one who proved it to be the oxygen we breathe. He also proved the Priestly was backward in his science.