Question: The inventor of Mayer's reagent and one of the founders of thermodynamics, Julius von Mayer was the first to enunciate what phrase, known as the first law of thermodynamics?

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Julius von Mayer: Julius Robert Mayer (November 25, 1814 – March 20, 1878) was a German physician, chemist and physicist and one of the founders of thermodynamics.  He is best known for enunciating in 1841 one of the original statements of the conservation of energy or what is now known as one of the first versions of the first law of thermodynamics, namely that "energy can be neither created nor destroyed".  In 1842, Mayer described the vital chemical process now referred to as oxidation as the primary source of energy for any living creature.  His achievements were overlooked and priority for the discovery of the "mechanical equivalent of heat" was attributed to James Joule in the following year.  He also proposed that plants convert light into chemical energy.

Ludwig A. Colding: Ludwig August Colding (13 July 1815 – 21 March 1888) was a Danish civil engineer and physicist who articulated the principle of conservation of energy contemporaneously with, and independently of, James Prescott Joule and Julius Robert von Mayer though his contribution was largely overlooked and neglected.

Mayer's reagent: Mayer's reagent is an alkaloidal precipitating reagent used for the detection of alkaloids in natural products.  Mayer’s reagent is freshly prepared by dissolving a mixture of mercuric chloride (1.36 g) and of potassium iodide (5.00 g) in water (100.0 ml).  Most alkaloids are precipitated from neutral or slightly acidic solution by Mayer’s reagent (potassiomercuric iodide solution) to give a cream coloured precipitate.  This test was invented by the German Chemist, Julius Robert Von Mayer (1814–1878).

Julius von Haast: Sir Johann Franz Julius von Haast {'1': ", '2': ", '3': ", '4': "} (born Johann Franz Julius Haast, 1 May 1822 – 16 August 1887), known as Julius Haast and later as Julius von Haast, was a German geologist.  He founded Canterbury Museum at Christchurch, New Zealand.

James Prescott Joule: James Prescott Joule FRS HFRSE DCL LLD ( ; (24 December 1818 11 October 1889) was an English physicist, mathematician and brewer, born in Salford, Lancashire.  Joule studied the nature of heat, and discovered its relationship to mechanical work (see energy).  This led to the law of conservation of energy, which led to the development of the first law of thermodynamics.

First law of thermodynamics: The first law of thermodynamics is a version of the law of conservation of energy, adapted for thermodynamic systems.  The law of conservation of energy states that the total energy of an isolated system is constant; energy can be transformed from one form to another, but can be neither created nor destroyed.  The first law is often formulated

Adiabatic process: In thermodynamics, an adiabatic process is one that occurs without transfer of heat or matter between a thermodynamic system and its surroundings.  In an adiabatic process, energy is transferred to its surroundings only as work.  The adiabatic process provides a rigorous conceptual basis for the theory used to expound the first law of thermodynamics, and as such it is a key concept in thermodynamics.

Levy Mayer: Levy Mayer (October 23, 1858 – August 14, 1922) was an American lawyer from Virginia.  A child prodigy of law, Mayer graduated from Yale Law School before he could even legally practice the profession in his hometown of Chicago, Illinois.  After several years organizing the Chicago Law Library, Mayer practiced with Adolf Kraus.  Mayer became one of the most infamous lawyers in Chicago by defending large corporations against anti-trust litigation.  Furthermore, he successfully defended the Iroqouis Theater and its manager in the aftermath of the Iroquois Theatre fire.  At the time of his death, he was considered one of the richest lawyers in the United States.  He is the namesake of Levy Mayer Hall at Northwestern University and his law firm is today known as Mayer Brown.

Richard D. Feinman: Richard David Feinman (born 1940) is a professor of biochemistry and medical researcher at State University of New York Health Science Center at Brooklyn, better known as SUNY Downstate Medical Center who studies nutrition and metabolism.  His current area of research is the area of diet composition and energy balance.  He is generally credited for doing the first serious scientific research on the Atkins Diet .  He has published articles on application of thermodynamics to nutrition.  His articles explain why the common idea that "a calorie is a calorie" is not correct.  His argument in brief: the first law of thermodynamics (conservation of energy) is a bookkeeping law, that it does not say how energy input is divided between weight gain, work done, heat generation or storage of energy in different biomolecules.  The second law is a dissipation law.  It says that all (real) processes are inefficient.  Feinman explained how diets of different composition vary in efficiency, in particular, how carbohydrate-restricted diets can lead to reduced efficiency.  Whereas the effect is not always seen, the argument is that there is no reason to doubt published reports where it does occur.

Rudolf Clausius: Rudolf Julius Emanuel Clausius (2 January 1822 – 24 August 1888) was a German physicist and mathematician and is considered one of the central founders of the science of thermodynamics.  By his restatement of Sadi Carnot's principle known as the Carnot cycle, he gave the theory of heat a truer and sounder basis.  His most important paper, "On the Moving Force of Heat", published in 1850, first stated the basic ideas of the second law of thermodynamics.  In 1865 he introduced the concept of entropy.  In 1870 he introduced the virial theorem which applied to heat.

Supporting paragraphs: Mayer's reagent Julius von Mayer
Answer: energy can be neither created nor destroyed