Editing Timeline of thermodynamics (section)

== 1800–1847 ==
* 1802&nbsp;– [[Joseph Louis Gay-Lussac]] publishes [[Charles's law]], discovered (but unpublished) by [[Jacques Charles]] around 1787; this shows the dependency between temperature and volume. Gay-Lussac also formulates the law relating temperature with pressure (the pressure law, or [[Gay-Lussac's law]])
* 1804&nbsp;– Sir [[John Leslie (physicist)|John Leslie]] observes that a matte black surface radiates heat more effectively than a polished surface, suggesting the importance of [[black-body radiation]]
* 1805&nbsp;– [[William Hyde Wollaston]] defends the conservation of energy in ''On the Force of Percussion''
* 1808&nbsp;– [[John Dalton]] defends caloric theory in ''A New System of Chemistry'' and describes how it combines with matter, especially [[gas]]es; he proposes that the [[heat capacity]] of gases varies inversely with [[atomic weight]]
* 1810&nbsp;– Sir John Leslie freezes water to ice artificially
* 1813&nbsp;– [[Peter Ewart]] supports the idea of the conservation of energy in his paper ''On the measure of moving force''; the paper strongly influences Dalton and his pupil, [[James Prescott Joule|James Joule]]
* 1819&nbsp;– [[Pierre Louis Dulong]] and [[Alexis Thérèse Petit]] give the [[Dulong-Petit law]] for the [[specific heat capacity]] of a [[crystal]]
* 1820&nbsp;– [[John Herapath]] develops some ideas in the kinetic theory of gases but mistakenly associates temperature with [[molecule|molecular]] [[momentum]] rather than [[kinetic energy]]; his work receives little attention other than from Joule
* 1822&nbsp;– [[Joseph Fourier]] formally introduces the use of [[dimension]]s for physical quantities in his ''Théorie Analytique de la Chaleur''
* 1822&nbsp;– [[Marc Seguin]] writes to [[John Herschel]] supporting the conservation of energy and kinetic theory
* 1824&nbsp;– [[Nicolas Léonard Sadi Carnot|Sadi Carnot]] analyzes the efficiency of [[steam engine]]s using [[caloric theory]]; he develops the notion of a [[reversible process (thermodynamics)|reversible process]] and, in postulating that no such thing exists in nature, lays the foundation for the [[second law of thermodynamics]], and initiating the science of thermodynamics
* 1827&nbsp;– [[Robert Brown (Scottish botanist from Montrose)|Robert Brown]] discovers the [[Brownian motion]] of [[pollen]] and dye particles in water <ref>{{Cite book|last=Brown, Robert, 1773-1858.|url=http://worldcat.org/oclc/38057036|title=A brief account of microscopical observations made in the months of June, July, and August, 1827, on the particles contained in the pollen of plants: and on the general existence of active molecules in organic and inorganic bodies ...|date=1828|publisher=A. and C. Black|oclc=38057036}}</ref>
* 1831&nbsp;– [[Macedonio Melloni]] demonstrates that black-body radiation can be [[Reflection (physics)|reflected]], [[refraction|refracted]], and [[Polarization (waves)|polarised]] in the same way as light
* 1834&nbsp;– [[Émile Clapeyron]] popularises Carnot's work through a graphical and analytic formulation. He also combined [[Boyle's law]], [[Charles's law]], and [[Gay-Lussac's law]] to produce a [[combined gas law]].  PV/T = k <ref>{{Cite book|last=CLAPEYRON, Benoît Paul Émile.|url=http://worldcat.org/oclc/559435201|title=Mémoire sur la puissance motrice de la chaleur.|date=1834|oclc=559435201}}</ref>
* 1841&nbsp;– [[Julius Robert von Mayer]], an [[amateur]] scientist, writes a paper on the conservation of energy, but his lack of academic training leads to its rejection
* 1842&nbsp;– Mayer makes a connection between work, heat, and the human [[metabolism]] based on his observations of blood made while a ship's surgeon; he calculates the [[mechanical equivalent of heat]]
* 1842&nbsp;– [[William Robert Grove]] demonstrates the thermal dissociation of molecules into their constituent atoms, by showing that steam can be disassociated into oxygen and hydrogen, and the process [[reversible process (thermodynamics)|reversed]]
* 1843&nbsp;– [[John James Waterston]] fully expounds the kinetic theory of gases,<ref>{{Cite book|last=Waterston, John J.|url=http://worldcat.org/oclc/328092289|title=Thoughts on the mental functions : being an attempt to treat metaphysics as a branch of the physiology of the nervous system.|date=1843|publisher=London|oclc=328092289}}</ref> but according to D Levermore "there is no evidence that any physical scientist read the book; perhaps it was overlooked because of its misleading title, Thoughts on the Mental Functions."<ref>{{Cite web|title=Neglected Pioneers|url=https://www.math.umd.edu/~lvrmr/History/Neglected.html|access-date=2020-12-20|website=www.math.umd.edu}}</ref>
* 1843&nbsp;– [[James Joule]] experimentally finds the mechanical equivalent of heat <ref>{{Cite journal|last=Joule|first=J.P.|date=1843|title=LII. On the calorific effects of magneto-electricity, and on the mechanical value of heat|url=https://www.tandfonline.com/doi/full/10.1080/14786444308644766|journal=The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science|language=en|volume=23|issue=154|pages=435–443|doi=10.1080/14786444308644766|issn=1941-5966}}</ref>
* 1845&nbsp;– [[Henri Victor Regnault]] added [[Avogadro's law]] to the [[combined gas law]] to produce the [[ideal gas law]]. PV = nRT
* 1846&nbsp;– Grove publishes an account of the general theory of the conservation of energy in ''On The Correlation of Physical Forces'' <ref>{{Cite book|last=Grove|first=W. R.|url=http://dx.doi.org/10.5962/bhl.title.19475|title=The correlation of physical forces (6th edition) by W.R. Grove.|date=1874|publisher=Longmans, Green|location=London|doi=10.5962/bhl.title.19475}}</ref>
* 1847&nbsp;– [[Hermann von Helmholtz]] publishes a definitive statement of the conservation of energy, the [[first law of thermodynamics]]<ref>{{Cite book|last=Helmholtz, Hermann v.|url=http://worldcat.org/oclc/488622067|title=Über die Erhaltung der Kraft, eine physikalische Abhandlung|date=1847|oclc=488622067}}</ref>