Julius von Mayer

German physician and physicist who, with James Joule, shared credit for discovering the universal law of conservation of energy. Due to controversy regarding whose discovery was first, Mayer’s contributions were little recognized until the 1860s.

He studied medicine at Tübingen, Munich and Paris, and while serving as a surgeon on a ship, Mayer studied the color difference between arterial and venous blood. Working independently of Joule, he concluded that the human body produces less energy by combustion when temperatures are elevated; this led him to determine the general relationship between heat and work. In 1842, he published his announcement regarding these findings in "Bemerkungen über die Kräfte der unbelebten Natur," and in 1845, he made a more general statement of the principle that came to be known as the first law of thermodynamics.

Mayer died on 20 March 1878 at age 63 in Heilbronn.