Editing Timeline of thermodynamics (section)

== 1848–1899 ==
* 1848&nbsp;– [[William Thomson, 1st Baron Kelvin|William Thomson]] extends the concept of absolute zero from gases to all substances
* 1849&nbsp;– [[William John Macquorn Rankine]] calculates the correct relationship between [[saturation vapor pressure|saturated vapour pressure]] and [[temperature]] using his ''hypothesis of molecular vortices''
* 1850&nbsp;– Rankine uses his ''vortex'' theory to establish accurate relationships between the temperature, [[pressure]], and [[density]] of gases, and expressions for the [[latent heat]] of [[evaporation]] of a liquid; he accurately predicts the surprising fact that the apparent [[specific heat]] of saturated [[steam]] will be negative
* 1850&nbsp;– [[Rudolf Clausius]] coined the term "entropy" (das Wärmegewicht, symbolized S) to denote heat lost or turned into waste. ("Wärmegewicht" translates literally as "heat-weight"; the corresponding English term stems from the Greek τρέπω, "I turn".)
* 1850&nbsp;– Clausius gives the first clear joint statement of the [[First law of thermodynamics|first]] and [[Second law of thermodynamics|second]] law of thermodynamics, abandoning the caloric theory, but preserving Carnot's principle
* 1851&nbsp;– Thomson gives an alternative statement of the second law
* 1852&nbsp;– Joule and Thomson demonstrate that a rapidly expanding gas cools, later named the [[Joule–Thomson effect]] or Joule–Kelvin effect
* 1854&nbsp;– Helmholtz puts forward the idea of the [[heat death of the universe]]
* 1854&nbsp;– Clausius establishes the importance of ''dQ/T'' ([[Clausius's theorem]]), but does not yet name the quantity
* 1854&nbsp;– Rankine introduces his ''thermodynamic function'', later identified as [[entropy]]
* 1856&nbsp;– [[August Krönig]] publishes an account of the kinetic theory of gases, probably after reading Waterston's work
* 1857&nbsp;– Clausius gives a modern and compelling account of the kinetic theory of gases in his ''On the nature of motion called heat''
* 1859&nbsp;– [[James Clerk Maxwell]] discovers the [[Maxwell–Boltzmann distribution|distribution law of molecular velocities]]
* 1859&nbsp;– [[Gustav Kirchhoff]] shows that energy emission from a [[black body]] is a function of only temperature and frequency
* 1862&nbsp;– "[[Disgregation]]", a precursor of [[entropy]], was defined in 1862 by Clausius as the magnitude of the degree of separation of molecules of a body
* 1865&nbsp;– Clausius introduces the modern [[macroscopic]] concept of entropy
* 1865&nbsp;– [[Josef Loschmidt]] applies Maxwell's theory to estimate the number-density of molecules in gases, given observed gas viscosities.
* 1867&nbsp;– Maxwell asks whether [[Maxwell's demon]] could reverse irreversible processes
* 1870&nbsp;– Clausius proves the scalar [[virial theorem]]
* 1872&nbsp;– [[Ludwig Boltzmann]] states the [[Boltzmann equation]] for the temporal development of [[Distribution function (physics)|distribution function]]s in [[phase space]], and publishes his [[H-theorem]]
* 1873&nbsp;- [[Johannes Diderik van der Waals]] formulates his [[equation of state]]
* 1874&nbsp;– Thomson formally states the [[second law of thermodynamics]]
* 1876&nbsp;– [[Josiah Willard Gibbs]] publishes the first of two papers (the second appears in 1878) which discuss phase equilibria, [[statistical ensemble]]s, the [[Thermodynamic free energy|free energy]] as the driving force behind [[chemical reaction]]s, and [[chemical thermodynamics]] in general.{{Citation needed|date=August 2010}}
* 1876&nbsp;– Loschmidt criticises Boltzmann's H theorem as being incompatible with microscopic reversibility ([[Loschmidt's paradox]]).
* 1877&nbsp;– Boltzmann states the relationship between entropy and [[probability]]
* 1879&nbsp;– [[Joseph Stefan|Jožef Stefan]] observes that the total radiant flux from a blackbody is proportional to the fourth power of its temperature and states the [[Stefan–Boltzmann law]]
* 1884&nbsp;– Boltzmann derives the Stefan–Boltzmann blackbody radiant flux law from thermodynamic considerations
* 1888&nbsp;– [[Henri-Louis Le Chatelier]] states his [[Le Châtelier's principle|principle]] that the response of a chemical system perturbed from equilibrium will be to counteract the perturbation
* 1889&nbsp;– [[Walther Nernst]] relates the voltage of electrochemical cells to their chemical thermodynamics via the [[Nernst equation]]
* 1889&nbsp;– [[Svante Arrhenius]] introduces the idea of [[activation energy]] for chemical reactions, giving the [[Arrhenius equation]]
* 1893&nbsp;– [[Wilhelm Wien]] discovers the displacement law for a blackbody's maximum specific intensity