Nitrous oxide, discovered in 1772 by Joseph Priestley, is the well-known "laughing gas". Nitrous oxide was first introduced as an anesthetic by Sir Humphry Davy. In the mid-1790s, Davy used the gas to soothe the pain of a toothache. Prepared usually by the decomposition of ammonium nitrate (NH₄NO₃), nitrous oxide is used today in food aerosols and is strictly intended for relatively short procedures in the operating room.