January 31st
1868 Theodore W. Richards was born. He was a researcher on atomic weights, electrochemistry and thermodynamics; discovered isotopes of lead from uranium and thorium. He was awarded the Nobel Prize in recognition of his accurate determinations of the atomic weight of a large number of chemical elements.
1881 Irving Langmuir was born. He was a researcher of surface chemistry, introduced gas-filled tungsten lamps and the use of atomic hydrogen blowpipe for welding. He invented the condensation pump for producing high vacuums and evolved electronic theory with Gilbert N. Lewis. He won the Nobel Prize (1932) for his discoveries and investigations in surface chemistry.