Classical Thermodynamics

Abstract

1. If we ignore the difference between Robert Mayer’s view of the concept of energy and Helmholtz’s — a difference which is profound, to be sure — we are left with two fundamental ideas as results of the development presented thus far. On the one hand, there is the equivalence of heat transfer with mechanical work, championed by Carnot and Clapeyron; and, on the other hand, there is the equivalence between heat energy and work which, at least in the judgment of contemporaries, received its greatest support from Joule’s experimental investigations. The former view is fully in harmony with the hypothesis that heat is a substance, since as heat loses its capacity for doing work, it, like falling water, nonetheless does not change its amount. The other idea impels one to think that heat is the motion of the smallest parts of bodies, since in working it ceases to exist, like motion which gives rise to another motion. In his work of 1847, Helmholtz is already aware of the contradiction between these two points of view; but Clausius was the first¹ to overcome it in his fundamental work of 1850.²