Joseph Priestly was fascinated by gases. He lived
near a brewery and noticed a heavy air with a distinct odor. He realized
that this gas, carbon dioxide, could extinguish a fire and if bubbled
through water would give it a pleasant and tangy taste (soda pop). He
also discovered in 1774, oxygen or what some people referred to as
"fire air" because it could burn. He also discovered that
plants released oxygen, and mice could survive with a plant inside a
glass jar. Priestly tried to adjust his discoveries with the Phlogiston
Theory. Prior to the 1760's people felt that "phlogistons"
were responsible for animals dying in an airtight container. Priestley
told French chemist Antoine Lavoisier of his discovery.
The Phlogiston Theory was then debunked by
Lavoisier as he refined Priestley’s experiments. This Frenchman used
precise measurements to become one of the first chemists to suggest that
air was composed of different gases.