On the Process of Establishing the Theory of Dissociation Equilibrium by A. Horstmann -The first step toward the formation of Chemical Thermodynamics late in the 19th century-

Abstract

August F. Horstmann is known to be the first chemist to have applied the second law of thermodynamics to chemical processes. He began to study the decomposition of substances by heat from the view-point of the kinetic theory of gases on one side (in 1868), and by the thermodynamical analogy with vaporizations on the other (in 1869). Next on th basis of the new thermodynamic formulation developed by Clausius in 1862, Horstmann promoted a better understanding with respect to the mutual relations between dissociation and thermodynamics. In 1871 he derived fundamental equations of dissociation equilibrium for substitution of watervapors with irons. A. Naumann criticized Horstmann's theory of dissociation, especially his application of a thermodynamic formula (so-called Clausius-Clapeyron's formula) to dissociation, from a standpoint of the molecular theory. Refuting Naumann's criticism, Horstmann showed that thermoclynamics and every formula deduced from it were not dependent upon any hypothesis on molecular processes, and therefore it was valid to apply thermodynamics to chemical changes Thus, in 1873 he attained a qualitatively high level of theory concerning dissociation equilibrium on the entropy maximization principle (formulated by Clausius in 1865). Then this new level of Horstmann's theory was established through his exact recognizing of the inner connection of chemical processes with the thermodynamic laws, and of the difference and the relation between microscopic processes and macroscopic ones.