Nitrogen

Daniel Rutherford asked a question regarding what happens if a candle is burned until no further burning air is possible, which led him to discover a new gas eventually called nitrogen. This gas does not support combustion or sustain life, showing it was neither combustible like oxygen nor able to support life like carbon dioxide.
 Daniel Rutherford England 1772 Nitrogen

Daniel Rutherford asked a question regarding what happens if a candle is burned until no further burning air is possible, which led him to discover a new gas eventually called nitrogen. This gas does not support combustion or sustain life, showing it was neither combustible like oxygen nor able to support life like carbon dioxide.