In 1774 Priestley discoverd oxygen by heating the calc of mercury and trapping the gas produced using Stephen Hales pneumatic trough. This is two years after Scheele did the same, but Priestley published first and now usually gets credit. A devout phlogistonist, he named the new gas "dephlogisticated air". (The name, oxygen, meaning "acid former", was later given by Lavoisier who believed that all acids contained this element.) Among his other accomplishments, Priestley discovered hydrochloric acid and sulfuric acid in 1775. He was also the first to write a detailed account of Benjamin Franklin's famous kite experiment.