Aside from what he learned in the local schools, he taught himself Latin, Greek, French, Italian, German and a smattering of Middle Eastern languages, along with mathematics and philosophy.
At the age of 19, the first student to enroll at the new dissenting academy in Daventry. He became a minister, but his interests and writings also encompassed science, history, education, and grammar.
Priestley’s scientific interests expanded to include the study of various gases, or “airs,”
as they were called at the time. Priestley was the first person to report the discovery of oxygen and describe some of its extraordinary properties.
He became a good friend of Benjamin Franklin who encouraged him to take up natural philosophy. In 1772 he began experiments on different airs (gases).
Priestley systematically analyzed the properties of different "airs" using the favored apparatus of the day: an inverted container on a raised platform that could capture the gases produced by various experiments below it.
Priestley called his discovery "dephlogisticated air" on the theory that it supported combustion so well because it had no phlogiston in it. Hence it could absorb the maximum amount during burning.
Lavoisier (1743–1794) repeated Priestley’s initial experiment and went on to describe the true nature of oxygen that had eluded Priestley, who never abandoned the erroneous phlogiston theory.
Joseph set sail for America on April 8, 1794. He died on February 6, 1804 at the age of seventy.
Joseph Priestley (1733-1804): English chemist
