Joseph Priestley (24 March 1733 – 6 February 1804) was an English chemist, natural philosopher, separatist theologian, grammarian, multi-subject educator, and liberal political theorist.He published over 150 works, and conducted experiments in electricity and other areas of science. He was a close friend of, and worked in close association with Benjamin Franklin involving electricity experiments.
Priestley is credited with his independent discovery of oxygen by the thermal decomposition of mercuric oxide,having isolated it in 1774.[9] During his lifetime, Priestley's considerable scientific reputation rested on his invention of carbonated water, his writings on electricity, and his discovery of several "airs" (gases), the most famousbeing what Priestley dubbed "dephlogisticated air" (oxygen). Priestley's determination to defend phlogiston theory and to reject what would become the chemical revolution eventually left him isolated within the scientific community.