One of his Chicago graduate students , Stanley L. Miller , showed in the Miller-Urey experiment that , if such a mixture be exposed to electric sparks and to water , it can interact to produce amino acids , commonly considered the building blocks of life .
Urey speculated that the early terrestrial atmosphere was probably composed of ammonia , methane and hydrogen ; it was one of his Chicago graduate students , Stanley L. Miller , who showed that , if such a mixture be exposed to electric sparks and to water , it can interact to produce amino acids , commonly called the `` building blocks of life '' ( see Miller-Urey experiment ) .