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Clausius’ Disgregation: A Conceptual Relic that Sheds Light on the Second Law

Department of Chemistry, University of Torino, Via Giuria 7, I-10125, Torino, Italy
Independent researcher, Viale delle acacie 12, I-10148, Vinovo, Italy
Author to whom correspondence should be addressed.
Academic Editor: Kevin H. Knuth
Entropy 2015, 17(7), 4500-4518;
Received: 5 May 2015 / Revised: 11 June 2015 / Accepted: 17 June 2015 / Published: 25 June 2015
(This article belongs to the Section Thermodynamics)
PDF [988 KB, uploaded 25 June 2015]


The present work analyzes the cognitive process that led Clausius towards the translation of the Second Law of Thermodynamics into mathematical expressions. We show that Clausius’ original formal expression of the Second Law was achieved by making extensive use of the concept of disgregation, a quantity which has subsequently disappeared from the thermodynamic language. Our analysis demonstrates that disgregation stands as a crucial logical step of such process and sheds light on the comprehension of such fundamental relation. The introduction of entropy—which occurred three years after the first formalization of the Second Law—was aimed at making the Second Law exploitable in practical contexts. The reasons for the disappearance of disgregation, as well as of other “pre-modern” quantities, from the thermodynamics language are discussed. View Full-Text
Keywords: disgregation; entropy; Second Law; Clausius disgregation; entropy; Second Law; Clausius
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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MDPI and ACS Style

Pellegrino, E.M.; Ghibaudi, E.; Cerruti, L. Clausius’ Disgregation: A Conceptual Relic that Sheds Light on the Second Law. Entropy 2015, 17, 4500-4518.

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