Onsager, Lars (1903–1976)
Norwegian-born American chemist awarded the 1968 Nobel Prize in Chemistry
for his fundamental work on irreversible chemical and thermodynamic processes.
In 1931 Onsager presented an explanation of the motion of ions in solution
which, although it received little attention at the time, has since been
called the fourth law of thermodynamics. From this theory,
Onsager developed a technique for producing uranium-235
(the basic fuel of nuclear reactors) from natural uranium (which consists
mainly of uranium-238). This technique was put into large-scale operation
at Oak Ridge, Tennessee, and remained the primary method for obtaining uranium-235
until the 1960s.