Editing Caloric theory (section)

==== Caloric theory ====
According to the caloric theory, the quantity of this substance is constant throughout the universe,{{Citation needed|date=January 2014}} and it flows from warmer to colder bodies. Indeed, Lavoisier was one of the first to use a [[calorimeter]] to measure the heat released during chemical reaction. Lavoisier presented the idea that caloric was a subtle fluid, obeying the common laws of matter, but attenuated to such a degree that it is capable of passing through dense matter without restraint; caloric's own material nature is evident when it is in abundance such as in the case of an explosion.<ref name=":0">{{Cite journal|last=Morris|first=Robert J.|date=1972|title=Lavoisier and the Caloric Theory|url=https://www.jstor.org/stable/4025261|journal=The British Journal for the History of Science|volume=6|issue=1|pages=1–38|doi=10.1017/S000708740001195X|jstor=4025261|s2cid=45598864 |issn=0007-0874|url-access=subscription}}</ref>

In the 1780s, [[Count Rumford]] believed that cold was a fluid, "frigoric", after the results of [[Pictet's experiment]]. [[Pierre Prévost (physicist)|Pierre Prévost]] argued that cold was simply a lack of caloric.

Since heat was a material substance in caloric theory, and therefore could neither be created nor destroyed, [[Conservation law|conservation]] of heat was a central assumption.<ref>See, for example, [[Nicolas Léonard Sadi Carnot|Carnot, Sadi]] (1824). ''Réflexions sur la Puissance Motrice du Feu''.</ref> Heat conduction was believed to have occurred as a result of the affinity between caloric and matter thus the less caloric a substance possessed, thereby being colder, attracted excess caloric from nearby atoms until a caloric, and temperature, equilibrium was reached.<ref name=":2">{{Citation|last=Brown|first=Sanborn C.|title=The Caloric Theory|date=1967|url=http://dx.doi.org/10.1016/b978-0-08-012179-6.50008-3|work=Men of Physics: Benjamin Thompson – Count Rumford|pages=16–24|publisher=Elsevier|doi=10.1016/b978-0-08-012179-6.50008-3|isbn=9780080121796|access-date=2021-12-03|url-access=subscription}}</ref>

Chemists of the time believed in the self-repulsion of heat particles as a fundamental force thereby making the great fluid elasticity of caloric, which does not create a repulsive force, an anomalous property which Lavoisier could not explain to his detractors.<ref>{{Cite book|last=Sage|first=Balthazar Georges|url=http://worldcat.org/oclc/1013352513|title=Mémoires de chimie|oclc=1013352513}}</ref>

Radiation of heat was explained by Lavoisier to be concerned with the condition of the surface of a physical body rather than the material of which it was composed.<ref name=":2"/> Lavoisier described a poor radiator to be a substance with a polished or smooth surface as it possessed its molecules lying in a plane closely bound together thus creating a surface layer of caloric which insulated the release of the rest within.<ref name=":2"/> He described a great radiator to be a substance with a rough surface as only a small amount of molecules held caloric in within a given plane allowing for greater escape from within.<ref name=":2"/> Count Rumford would later cite this explanation of caloric movement as insufficient to explain the radiation of cold becoming a point of contention for the theory as a whole.<ref name=":2"/>

The introduction of the caloric theory was influenced by the experiments of [[Joseph Black]] related to the thermal properties of materials. Besides the caloric theory, another theory existed in the late eighteenth century that could explain the phenomenon of heat: the [[kinetic theory of gases|kinetic theory]]. The two theories were considered to be equivalent at the time, but kinetic theory was the more modern one, as it used a few ideas from [[atomic theory]] and could explain both combustion and calorimetry. Caloric theory's inability to explain evaporation and sublimation further led to the rise of kinetic theory through the work of Count Rumford. Count Rumford observed solid mercury's tendency to melt under atmospheric conditions and thus proposed that the intensity of heat itself must stem from particle motion for such an event to occur where great heat was not expected to be.<ref name=":3" />