CO, CO2, H2, N2, H2O, S, HCl, HCN, but NO!!! O2.
Salts, methane, ammonia, hydrogen, and water
He wanted to demonstrate that the application of UV radiation, heat, or combination of these to a mixture of methane, hydrogen, ammonia, and water could result in the formation of complex organic compounds.
So he set up an apparatus in which the 4gases were continuously circulated past electrical discharges from tungsten electrodes
After circulating for a week, he analyzed the liquid in the apparatus and found that an amazing variety of organic compounds, including urea, hydrogen cyanide, acetic acid, and lactic acid had been synthesized