General view of chemist Abraham Rednor placing a sample in the subambient temperature chamber of a Perkin-Elmer differential scanning calorimeter at the U.S. Army Chemical Test Branch laboratory located in Edgewood, Maryland. Per notations accompanying the photograph, the sample was heated through its melting stage in order to measure the heat absorbed against the temperature of the material as it was melting. Through this analysis, chemists measure the heat of fusion of the material, as well as it melting temperature, melting range, and degree of purity.