Julius Robert von Mayer

Julius Robert von Mayer, born on November 25, 1814, was one of the pioneers of thermodynamics for enunciating one of the first formulations of the First Law: "Energy can not be created or destroyed".

Mayer grew up in Heilbronn, in southern Rhineland, the son of a pharmacist he studied medicine at the University of Tubingen. After attaining his doctorate, he signed on as ship's physician on Dutch three-masted sailing ship on a trip to Jakarta.

This trip spurred his interest in the physical sciences. His observation that wind swept waves were warmer than calm seas led him to wonder about the physical phenomenon of warmth. Also while in the tropics he observed that the blood of his patients was redder than it would be in northern climes. While operating on a patient he saw the redder blood and feared he had severed an artery. Only after being reassured by local physicians did he realize that this was normal. In the tropics not as much oxygen is required to warm the body and thus the blood traveling back to the heart is more oxygenated and redder than venous blood in cooler climes where more oxygen is required to maintain temperature. This led Mayer to believe that oxidation was the primary source of energy in living things.

Upon returning to Germany Mayer wrote a paper outlining his observations, however the paper contained no experimental results and was rejected. Unable to get clarification on why his paper was rejected Mayer (relying on the experimental work of others) wrote another paper in which he proposed that mechanical energy and heat energy were equivalent, specifically that the dropping of a weight from 365meters was equivalent to warming an equivalent mass of water from 0 to 1 degree Celsius. The current accepted value for this standard is 418.4meters.

At the time Mayer's work was largely ignored and credit for the discovery of the equivalence of mechanical and heat energy was initially given to James Joule (for whom the unit of energy is named). In 1848 when Mayer tried to assert his precedence, Joule admitted Mayer's precedence but claimed credit for the experimental demonstration of the theory. This controversy, plus the loss of two of his children, caused Mayer to attempt suicide in 1850. Mayer's work led Herman von Helmholtz to formulate the general principal of conservation of energy in 1848.

For his work in describing the principal of the conservation of energy Julius Robert von Mayer is the Dead Scientist of the Week for the week of November 22-28, 2009.

References:

Julius Robert von Mayer Wikipedia Entry

Mechanical equivalent of heat Wikipedia Entry

Cobb, Kathy; Goldwhite, Harold; Creations of Fire: Chemistry's Lively History from Alchemy to the Atomic Age; Basic Books, 2002