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A Synopsis of Classical Thermodynamics
Published in R. Ravi, Chemical Engineering Thermodynamics, 2020
The notion of interconvertibility between heat and work is inherent in Carnot’s work as seen from his axioms, eqs. (20) and (21). In those equations, the work is related to the heat absorbed in the Carnot cycle. If one adopts the caloric theory as Carnot did, then the heat emitted equals the heat absorbed and the net heat interaction of the cycle is zero. Clapeyron, who generalized Carnot’s results to fluids with a general equation of state, also adopted the caloric theory but nevertheless remarked that “a quantity of mechanical action, and a quantity of heat which can pass from a hot body to a cold body, are quantities of the same nature.” Mendoza (p. 81 of [11]), in a footnote, regards this as “…an unambiguous statement of the First Law of thermodynamics”. However, as explained in section 1.6.1 below, the caloric theory contradicts the first law of thermodynamics. Thus Clapeyron could not have proposed the first law of thermodynamics and at the same time employed the caloric theory. In summary, a mere verbal assertion of a certain equivalence between heat and work does not imply the first law of thermodynamics. We will examine the work of Mayer, Holtzmann, Joule and Helmholtz in this light.
Analysis of Thermal Energy Systems
Published in Steven G. Penoncello, Thermal Energy Systems, 2018
Envisioning thermodynamic quantities requires abstract thought. For example, we can physically sense heat, but how can it be quantified? From your previous course(s) in thermodynamics, you learned that heat is a form of energy that is transferred due to a temperature difference. However, heat was not always considered energy. From 1697 to 1703, German chemist Georg Stahl proposed the phlogiston theory. Stahl theorized that heat was a fire-like element called phlogiston. Phlogiston was contained within substances and was released during combustion which produced the sensation of heat. The phlogiston theory was superseded by the caloric theory, developed by French chemist Antoine Lavoisier with a series of papers published from 1768 to 1787. Lavoisier proposed that heat was actually a fluid called caloric and it flowed from one substance to another. As caloric entered a substance, it would expand. The caloric theory eventually gave way to the concept of heat as energy.
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Published in Splinter Robert, Illustrated Encyclopedia of Applied and Engineering Physics, 2017
[general] caloric theory, introduced in the 1760s defined thermal energy as a fluid; caloric. Caloric was supposedly indestructible and could not be created. This medium of energy was a radical change from concepts of internal motion hypothesized as far back as Plato (427–347 BC). The work of Benjamin Thompson (Count Rumford) (1753–1814) repealed the caloric concept in 1798 to the base concepts of Plato and further theoretical evolution of the kinetic theory, reiterating that work performed can generate heat.
The elements: a visual history of their discovery
Published in Annals of Science, 2022
A particularly welcome feature of this book is that not all sections are dedicated to elements to be found on a present-day periodic table. (Ball does provide readers with a periodic table at the beginning of the book and element-specific IUPAC group, atomic number, and atomic weight where applicable.) ‘The Classical Elements’ addresses the water, air, fire, and earth of the Greek tradition, but also the concept of substance per se (‘Prote Hyle’), the five-element Chinese wuxing (water, fire, earth, wood, and metal), Greek atomism, and aether (from Aristotle’s quintessence to, on the one hand, a class of organic compounds and, on the other, the luminiferous aether of Maxwellian physics). Later chapters include sections on phlogiston and caloric. Ball writes that the latter exemplifies how ‘scientists often only come to the right conclusions by leaning on notions that are later disproven: they are not errors or mistakes, but rather signposts along the road to a better understanding of the world’ (pp. 123–124). Many sections feature a pithy generalization of this sort, a call-out to longstanding familiarity with materials prior to their ‘discovery’ (e.g. working of platinum by pre-colonial peoples in present-day Colombia and Ecuador), or other such digestible expression of historical sensibility. This diverges in striking fashion from the extreme whiggism of historical narratives of much popular science. (In my own youthful favourite, The God Particle, Lederman assigns grades to historical figures based on their contributions to the progress of atomism. Newton earns a C.) That said, Ball is not out to challenge the common-sense realism of present-day chemistry regarding what is an element and what isn’t. Caloric theory contributed to the development of thermodynamics; ‘still, fictitious it [caloric] is’ (p. 124).