In 1953, Stanley Miller tested whether the prebiotic synthesis of organic molecules was
possible. He simulated the condition of early Earth in a specially designed apparatus (figure 1).
Water was boiled and the vapor rose into the chamber containing hydrogen gas (H2), methane
(CH4), and ammonia (NH3). Two electrodes were inserted into the chamber. The electrodes released
electrical discharge as if it was a lightning bolt. Gaseous substances that had been formed moved
pass a cold condenser and then precipitated. A portion of the sample was collected in a flask and the
rest was re-circulated in the apparatus. For the first round of the experiment, Miller found hydrogen
cyanide (HCN) and formaldehyde (CH2O). These small precursors were combined to form larger
molecules such as amino acid glycine in later round of the experiments.