Julius Robert von Mayer

Julius Robert von Mayer (November 25, 1814 – March 20, 1878) was a German physician and physicist. He described the vital chemical process now referred to as oxidation as the primary source of energy for any living creature in 1842.

Development of ideas

He sent a paper to Johann Christian Poggendorff's Annalen der Physik in which he postulated a Erhaltungssatz der Kraft, by which he meant a conservation law energy. However, owing to Mayer's lack of advanced training in physics, it contained some fundamental mistakes and was not published. Mayer continued to pursue the idea steadfastly and argued with the Tübingen physics professor Johann Gottlieb Nörremberg, who rejected his hypothesis. Nörremberg however, gave a number of valuable suggestions on how it could be examined experimentally. If kinetic energy transforms into heat energy, water must be warmed up by vibrating.

Related Topics:
Johann Christian Poggendorff - Annalen der Physik - Conservation law - Energy - Physics - Tübingen - Johann Gottlieb Nörremberg - Hypothesis - Kinetic energy - Heat - Water - Vibrating

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Mayer not only performed this demonstration, but determined also the quantitative factor of the transformation, the mechanical equivalent of heat. The result of his investigations was published 1842 in the May edition of Justus von Liebig's Annalen der Chemie und Pharmacie. In his booklet Die organische Bewegung im Zusammenhang mit dem Stoffwechsel (The Organic Movement in Connection with the Metabolism (1845) he could specified the numerical value of the mechanical equivalent of heat: at first as 365 kgf·m/kcal{{ref|kpm}}, later as 425 kgf·m/kcal; the modern values are 4.184 kJ/kcal (426.6 kgf·m/kcal) for the thermochemical calorie and 4.1868 kJ/kcal (426.9 kgf·m/kcal) for the international steam table calorie.

Related Topics:
1842 - Justus von Liebig - Annalen der Chemie und Pharmacie - 1845 - Kgf - KJ

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This relation implies that work and heat equivalent to each other and are different forms of energy which can be transformed. This law is called the first law of the caloric theory and led to the formulation of the general principle of conservation of energy, definitively stated by Hermann von Helmholtz in 1847.

Related Topics:
Caloric theory - Conservation of energy - Hermann von Helmholtz - 1847

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Meyer derived what is now known as Mayers' relation:

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:Cp - Cv = R

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