Josef Loschmidt

Johann Josef Loschmidt (1821-1895), while relatively little-known today, made major contributions to physical chemistry, thermodynamics, electromagnetism and organic chemistry. His work on the size of molecules was sufficiently important that in German-speaking countries, "Loschmidt's number" is the term for what English-speaking countries call Avogadro's number.

Loschmidt, to historians of science, is a man whose name should have been on more basic ideas, or at least a coauthor. He conceived the concept of a benzene ring before Friedrich Kekulé, but did not have the chemical bonding quite right. His contributions to thermodynamics led to the work by James Clerk Maxwell and Ludwig Boltzmann. Heinrich Hertz built on his ideas.