Hermann Kopp. Portrait of Hermann Franz Moritz Kopp (1817-92), German chemist and historian of chemistry. Professor at Geissen and Heidelberg, Kopp researched the relationship between the physical properties of elements or compounds and their chemical composition. He made accurate measurements of properties such as boiling points, specific heats, densities, and developed the concepts of atomic volume and molecular volume. He wrote a major history of chemistry Geschichte der Chemie (4 volumes) between 1843 and 1847. He was thus one of the founders of physical chemistry.