Back to top In 1767, Priestley was offered a ministry in Leeds, Englane, located near a brewery.
This abundant and convenient source of "fixed air” — what we now know as carbon dioxide — from fermentation sparked his lifetime investigation into the chemistry of gases.
His unorthodox religious writings and his support for the American and French revolutions so enraged his countrymen that he was forced to flee England in 1794.
He settled in Pennsylvania, where he continued his research until his death.
The world recalls Priestley best as the man who discovered oxygen, the active ingredient in our planet's atmosphere.
In the process, he helped dethrone an idea that dominated science for 23 uninterrupted centuries: Few concepts "have laid firmer hold upon the mind," he wrote, than that air "is a simple elementary substance, indestructible and unalterable." In a series of experiments culminating in 1774, Priestley found that "air is not an elementary substance, but a composition," or mixture, of gases.Researchers had distinguished no more than two dozen or so elements, depending on who was doing the counting. Nobody knew what it was, and researchers kept finding that it could be converted into such a variety of forms that they routinely spoke of different "airs." The principal method for altering the nature of air, early chemists learned, was to heat or burn some compound in it.The second half of the 1700s witnessed an explosion of interest in such gases.Before long, he was encouraged to study for the ministry.And study, as it turned out, was something Joseph Priestley did very well.Priestley (1733-1804) was hugely productive in research and widely notorious in philosophy.He invented carbonated water and the rubber eraser, identified a dozen key chemical compounds, and wrote an important early paper about electricity.He found a way to produce artificially what occurred naturally in beer and champagne: water containing the effervescence of carbon dioxide.The method earned the Royal Society's coveted Copley Prize and was the precursor of the modern soft-drink industry.His first full-time teaching position was at the Dissenting Academy in Warrington.(Although obviously brilliant, original, outspoken and, by one report, of "a gay and airy disposition," Priestley had an unpleasant voice and a sort of stammer.