Urey, Harold Clayton (1893-1981)

US chemist. In 1932 he isolated heavy water and was awarded the Nobel Prize for Chemistry in 1934 for his discovery of deuterium (heavy hydrogen).

During World War II he was a member of the Manhattan Project, which produced the atomic bomb, and after the war he worked on tritium (another isotope of hydrogen, of mass 3) for use in the hydrogen bomb, but later he advocated nuclear disarmament and world government.

Urey was born in Indiana and educated at Montana State University. He became professor of chemistry at Columbia 1934, and was at Chicago 1945-58.

After deuterium, Urey went on to isolate heavy isotopes of carbon, nitrogen, oxygen, and sulphur. His group provided the basic information for the separation of the fissionable isotope uranium-235 from the much more common uranium-238.

Urey also developed theories about the formation of the Earth. He thought that the Earth had not been molten at the time when its materials accumulated. In 1952, he suggested that molecules found in its primitive atmosphere could have united spontaneously to give rise to life. The Moon, he believed, had a separate origin from that of the Earth.