Rock salt prism used in pioneering work on the infra-red spectrum, 1920-1940

Rock salt prism used by Sutherland and Sheppard in infra-red research

The prism was used by Sir Gordon Sutherland and Norman Sheppard at Cambridge during the Second World War in the analysis of hydrocarbons present in enemy fuels using infra-red spectroscopy. One such use was to determine to what extent Germany was converting coal into oil. The prism was used in conjunction with infra-red diffraction gratings, also acquired, which had been purchased in the 1930s from Michigan University. Acquisition of these items by the Science Museum provides the opportunity for strong stories on the use of novel scientific techniques in warfare, and of the use of science by the state.