Year 1774: English chemist Joseph Priestley discovers oxygen

Joseph Priestley was born near Leeds on 13th March 1733, the eldest son of a cloth-dresser. His scientific interests began around the middle of the 1760s. He began to write his book "History and Present State of Electricity" and was helped by the likes of Benjamin Franklin, William Watson and John Canton.

Priestley entered the service of the Earl of Shelburne in 1773 and it was while he was in this service that he discovered oxygen. In a classic series of experiments he used his 12inch "burning lens" to heat up mercuric oxide and observed that a most remarkable gas was emitted. Although oxygen was his most important discovery, Priestley also described the isolation and identification of other gases such as ammonia, sulphur dioxide, nitrous oxide and nitrogen dioxide. He was also involved with the Lunar Society - a small group of academics, scientists and industrialists with wide ranging interests who were prominent in spearheading the Industrial Revolution in England. Priestley died on 5th February, 1804.

Here is a book on the life and works of Joseph Priestley.