The above process using ammonia, methane, and an electric discharge to produce amino acids is based on Stanley Miller's experiment in which he ran an electric discharge through a mixture of water vapor, hydrogen, methane, and ammonia. About a 10% yield of biological compounds, such as sugars, amino acids, etc. were found. Sidney Fox heated a solution of amino acids and protocells were formed. Protocells were considered "quasi-life"; although they could not be classified as cells, they divided and grew.