Julius von Mayer

Julius Robert von Mayer (1814 to 1878) was a German physician, chemist and physicist, counted among the founders of thermodynamics. In 1841 he set out one of the original statements of the conservation of energy, an early version of what is now called the first law of thermodynamics, namely that energy can be neither created nor destroyed. In 1842 he described oxidation as the vital chemical process that is the primary source of energy for any living creature, and he also proposed that plants convert light into chemical energy. His achievements were overlooked at the time, and priority for the 1842 discovery of the mechanical equivalent of heat was attributed to James Joule the following year. He belongs in a medical atlas as a trained physician whose work on energy and metabolism bore directly on how the living body was understood.