Theory caloric

The second law as it left the hands of Carnot required no explanation. On the caloric theory then prevalent, it was a necessary consequence of a hydrodynamical analogy—the mechanical explanation was in fact, as Carnot s words show, the source of the principle. When the caloric theory was thrown down, the analogy and explanation fell with it, and the reconstruction of Carnot s principle by Clausius and Kelvin resulted in a law of experience. 

The equations of 59—61 are independent of the mechanical, theory of heat, and would apply equally well to the caloric theory. In the latter case, however, SQ is a perfect differential. They are also unchanged when T is put for 6, where T is the absolute temperature. All the twelve relations can be derived from the four in the first column, together with the equations (4). 

Thus, within the context of the Newtonian force atom and the caloric theory of heat, solids, liqitids, and gases were all viewed as organized arrays of particles produced by a static equilibrium between the attractive interparticle forces, on the one hand, and the repulsive intercaloric forces, on the other. The sole difference was that the position of eqitilibriitm became greater as one passed from the solid to the liqitid to the gas, due to the increasing size of the caloric envelopes siuToittrding the component atoms (Figures 5 and 6). 

Figure 5. The author s graphical interpretation of the caloric theory of states.

Rumford s studies (along with those of Humphrey Davy see Section 3.4) contributed to gradual decline of the caloric theory of heat and its replacement by the modem kinetic molecular theory. By about 1840, the interconversion of heat and work was clearly understood, as well as the association of heat with molecular motion. However, there was as yet no clear statement of the conservation principle for the total heat plus work. 

Around 1800, experimental challenges to caloric theory were being presented by Count Rumford (cannon boring) and Humphrey Davy (melting of ice by friction). It became apparent that heat could be produced from a body in unlimited quantity by friction, further stretching its credibility as a substance. By about 1840, caloric theory was overturned by the modem kinetic molecular theory of heat (Sidebar 2.7), which identified heat with the energy of random molecular motions. 

The caloric theory of heat pictured heat as a fluid which permeates all materials. What experimental evidence clearly made this theory untenable, regardless of the properties assigned to the caloric fluid Why ... 

Nineteenth Century Chemistry Caloric Theory and Thermodynamics Lavoisier proposed in the late 18th century that the heat generated by combustion was due to a weightless material substance called caloric that flowed from one place to another and was never destroyed. 

Sadi Carnot in the 1820s used caloric theory in developing theories for the heat engine to explain the engine already developed by Watt. Heat engines perform mechanical work by expanding and contracting a piston at two different temperatures. 

James Prescott Joule determined the equivalence of heat energy to mechanical work in the 1840s by carefully measuring the heat produced by friction. Joule attacked the caloric theory and played a major role in the acceptance of kinetic molecular theory. The SI unit of energy is named after him. 

William Thomson, 1st Baron of Kelvin also called Lord Kelvin recognized the existence of absolute temperature in the 1840s and proposed the temperature scale named after him. He failed in an attempt to reconcile caloric theory with Joule s discovery and caloric theory began to fall out of favor. 

Hermann von Helmholtz in the 1840s proposed that energy is conserved during physical and chemical processes, not heat as proposed in caloric theory... 

See H. Chang, Inventing Temperature Measurement and Scientific Progress, (Oxford Oxford University Press, 2004), pp. 168-70. On Dalton and Irvinism see R. Fox, The Caloric Theory of Gases from Lavoisier to Regnault (Oxford Clarendon Press, 1971), pp. 104-15. 

Other, better known, extenders of Black s work in this sense were, of course, William Irvine, Adair Crawford and William Cleghorn on whom see Donovan, Philosophical Chemistry, pp. 27 Iff. See also Fox, The Caloric Theory of Gases, Chapter 1. 

Fox, R., The Caloric Theory of Gasesfrom Lavoisier to Regnault (Oxford The Clarendon Press, 1971). 

There were some contradictions in Carnot s work—a result of his reliance on the caloric theory—that were subsequently cleared up by Clausius. Clausius accepted Carnot s proposition that some heat must be thrown away when converting heat to work as a law of nature, something that cannot be proved or derived from something else, but as far as we have ever been able to tell describes the way the world works. He called it the second law of thermodynamics and then sought to recast it in a different, more general, form that did not apply to heat engines alone. He showed that an equivalent statement of the... 

Robert J. Morris, Lavoisier and the Caloric Theory, British Journal for the History of Science 6, 1972, 1-38, at 14—15. 

Lavoisier, Reflexions sur le phlogistique pour servir de developpement a la theorie de la combustion de la calcination, publiee en 1777, Oeuvres, volume 2, 623-655 A short description in Robert). Morris, Lavoisier and the Caloric Theory, British Journal for the History of Science 6, 1972, 1-38, at 16-21 Guerlac, Lavoisier, 258-261. 

H. E. Le Grand, Genius and the Dogmatization of Error The Failure of C. L. Berthollet s Attack upon Lavoisier s Acid Theory, Organon 12-13,1976-77, 193-209 Robert Fox, The Caloric Theory of Gases (Clarendon, 1971). 

Morris, Robert J. Lavoisier and the Caloric Theory. BJFiS 6, 1972, 1-38. Muirhead, James Patrick. Correspondence of the Late James Watt on Flis Discovery of the Theory of the Composition of Water (London J. Murray Edinburgh W Blackwood, 1846). 

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