In science, theory of heat, or "heat theory", refers to number of theories employed to explain the nature of heat, namely: material theory of heat (or fluid theory of heat), kinetic theory of heat, wave theory of heat, among others.

In the 1830s, French writers began to use the therm "theory of heat" as the subject of the study of the phenomena of radiation, conduction, expansion of bodies, and light according to the doctrine that heat is a state of vibration. [1] This was in contrast to the older, but still in debate, during these years, “caloric theory” by French chemist Antoine Lavoisier, which viewed heat as a fluid-like indestructible substance called caloric.

Transition to thermodynamics
In the 1850s, the theory of heat was unified with the mechanical equivalent of heat, in the production of heat by work or work by heat, particularly in heat engines, into the “Mechanical Theory of Heat” by German physicist Rudolf Clausius. [2] This work soon led to the development of the new science of "thermo-dynamics", an early outlines of which can be found in British physicist William Thomson’s 1851 paper “On the Dynamical Theory of Heat”. [3]

Theory of Heat
In 1871, Scottish mathematical physicist James Maxwell published his Theory of Heat, geared toward the layman, and after discovering the 1873 graphical thermodynamics work of American engineer Willard Gibbs, made a substantial revised 1875 edition, wherein he incorporated his sketches of his Maxwell thermodynamic surface, correcting his earlier views on entropy, which were based on Peter Tait.

1. Kelland, Philip. (1837).
Theory of Heat. Cambridge University Press.
2. Clausius, R. (1865). The Mechanical Theory of Heat – with its Applications to the Steam Engine and to Physical Properties of Bodies. (Google Books). London: John van Voorst, 1 Paternoster Row. MDCCCLXVII.
3. Thomson, William. (1851). “On the Dynamical Theory of Heat.” Transactions of the Royal Society of Edinburgh, March.

Further reading
● Maxwell, James C. (1872). Theory of Heat (313 pgs). London: Longmans, Green, and Co.
● Preston, Thomas. (1894). Theory of Heat (719 pgs). London: MacMillan and Co.

External links
Theory of heat – Wikipedia.

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