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ULTRA-VIOLET STERILIZATION•see
STERILIZATIONUUrey, Harold REY, HAROLD (1893-1981)
American biochemistAlready a scientist of great honor and achievement, Harold
Urey’s last great period of research brought together his inter-
ests and experiences in a number of fields of research to which
he devoted his life. The subject of that research was the origin
of lifeon Earth.
Urey hypothesized that the earth’s primordial atmo-
sphere consisted of reducing gases such as hydrogen, ammo-
nia, and methane. The energy provided by electrical
discharges in the atmosphere, he suggested, was sufficient to
initiate chemical reactions among these gases, converting
them to the simplest compounds of which living organisms are
made, amino acids. In 1953, Urey’s graduate student Stanley
Lloyd Miller carried out a series of experiments to test this
hypothesis. In these experiments, an electrical discharge
passed through a glass tube containing only reducing gases
resulted in the formation of amino acids.
The Miller-Urey experimentis a classic experiment in
biology. The experiment established that the conditions that
existed in Earth’s primitive atmosphere were sufficient to pro-
duce amino acids, the subunits of proteins comprising and
required by living organisms. In essence, the Miller-Urey
experiment fundamentally established that Earth’s primitive
atmosphere was capable of producing the building blocks of
life from inorganic materials.
The Miller-Urey experiment also remains the subject of
scientific debate. Scientists continue to explore the nature and
composition of Earth’s primitive atmosphere and thus, con-
tinue to debate the relative closeness of the conditions of the
experimental conditions to Earth’s primitive atmosphere.The Miller-Urey experiment was but one part of a dis-
tinguished scientific career for Urey. In 1934, Harold Urey was
awarded the Nobel Prize in chemistry for his discovery of deu-
terium, an isotope, or species, of hydrogen in which the atoms
weigh twice as much as those in ordinary hydrogen. Also
known as heavy hydrogen, deuterium became profoundly
important to future studies in many scientific fields, including
chemistry, physics, and medicine. Urey continued his research
on isotopes over the next three decades, and during World War
II his experience with deuterium proved invaluable in efforts to
separate isotopes of uranium from each other in the develop-
ment of the first atomic bombs. Later, Urey’s research on iso-
topes also led to a method for determining the earth’s
atmospheric temperature at various periods in past history. This
experimentation has become especially relevant because of
concerns about the possibility of global climate change.
Harold Clayton Urey was born in Walkerton, Indiana.
His father, Samuel Clayton Urey, was a schoolteacher and lay
minister in the Church of the Brethren. His mother was Cora
Reinoehl Urey. After graduating from high school, Urey
hoped to attend college but lacked the financial resources to do
so. Instead, he accepted teaching jobs in country schools, first
in Indiana (1911–1912) and then in Montana (1912–1914)
before finally entering Montana State University in September
of 1914 at the age of 21. Urey was initially interested in a
career in biology, and the first original research he ever con-
ducted involved a study of microorganismsin the Missoula
River. In 1917, he was awarded his bachelor of science degree
in zoology by Montana State.
The year Urey graduated also marked the entry of the
United States into World War I. Although he had strong paci-
fist beliefs as a result of his early religious training, Urey
acknowledged his obligation to participate in the nation’s war
effort. As a result, he accepted a job at the Barrett Chemical
Company in Philadelphia and worked to develop high explo-
sives. In his Nobel Prize acceptance speech, Urey said that this
experience was instrumental in his move from industrial
chemistry to academic life.womi_U 5/7/03 9:41 AM Page 563