Clausius’ Disgregation and other disappeared thermodynamic quantities: conceptual relics or meaningful epistemic junctions?

The present paper is based on the analysis of some foundational works by Clausius (namely the Sixth and Ninth Memoires) and analyses the stepwise process that led Clausius to translate the qualitative statement of the Second Law of thermodynamics into mathematical expressions. The epistemic role of the thermodynamic quantities that were part of Clausius’ formal system is discussed. In particular, we analyse the meaning of disgre-gation and other pre-modern quantities that stem from Clausius’ micro-scopic model of matter, as essential precursor of entropy