Born March 24, 1733

Fieldhead, England

Died February 6, 1804

Northumberland, Pennsylvania

Scientist, philosopher, teacher, minister

Joseph Priestley. International Portrait Gallery.

"Truth can never have a fair chance of being discovered, or propagated, without the most perfect freedom of inquiry and debate."

Joseph Priestley is credited for being one of the founding fathers of the science known as chemistry. In addition to discovering oxygen, he conducted experiments with fixed air (carbon dioxide), which eventually led to the development of carbonated beverages, or soda pop. His good friend Benjamin Franklin (1706–1790) aroused his interest in electricity, and it was Priestley who discovered that graphite is a useful electrical conductor. In addition to his scientific interests, Priestley was a published philosopher whose beliefs differed from the religious majority of the day. As a result, he and his family were outcasts, subjected to ridicule and physical violence. Priestley brought to America a new...