Miller and Urey performed an experiment to prove the origin of life. What was the gases that they used to perform this experiment?

CH_4,NH_3, water vapours ,H2

The conditions on earth were – high temperature, volcanic storms, reducing atmosphere containing CH4 , NH3 , etc. In 1953, S.L. Miller, an American scientist created similar conditions in a laboratory scale . He created electric discharge in a closed flask containing CH4 , H2 , NH3 and water vapour at 800 degree Celsius .He observed formation of amino acids. In similar experiments others observed, formation of sugars, nitrogen bases, pigment and fats.