In his most famous experiment he placed a candle and a plant in a jar and concluded that candles and organisms destroy the air while plants replenish it with what he called "dephlogisticated air."  
A pastor of Leeds as well as a scientist, this man's first experiments involved the discovery that brewery gas extinguishes wood chips.  A meeting with Benjamin Franklin led to the discovery that graphite conducts electricity, which he documented in his book The History of Electricity. In his most famous experiment he placed a candle and a plant in a jar and concluded that candles and organisms destroy the air while plants replenish it with what he called "dephlogisticated air."  FTP, name this English scientist, the discoverer of oxygen.
A pastor of Leeds as well as a scientist, this man's first experiments involved the discovery that brewery gas extinguishes wood chips.  
Joseph Priestley