Joseph Priestley

Joseph Priestley was an English natural philosopher, dissenting theologian, political theorist, and chemist who isolated more gases than any other scientist of the eighteenth century. A close friend of Benjamin Franklin, Priestley began his scientific career studying electricity before turning to the chemistry of 'airs' (gases).

On August 1, 1774, focusing sunlight through a twelve-inch burning lens onto red mercuric oxide in a pneumatic trough, Priestley isolated a gas in which a candle burned with vigorous brilliance and mice survived twice as long as in common air. Calling it 'dephlogisticated air', he shared his findings with Antoine Lavoisier in Paris, who recognized it as the elemental gas oxygen. Priestley also discovered carbon monoxide, nitrous oxide, nitric oxide, ammonia, sulfur dioxide, and hydrogen chloride. In 1767, after living next to a brewery in Leeds, he invented carbonated water (soda water) by dissolving carbon dioxide in water. Attacked by religious and royalist mobs who burned his home and laboratory in the 1791 Priestley Riots, he fled to America.