‎"CLAUSIUS, R. (RUDOLF). - THE SECOND LAW OF THERMODYNAMICS.‎
‎Ueber einen Grundsatz der mechanischen Wärmetheorie. (The mechanical theory of heat). (Vorgetragen am 25. August 1863 in der zu Samaden abgehaltenes Versammlung der schweizerischen naturforschenden Gesellscahft).‎

‎Leipzig, Johann Ambrosius Barth, 1863. Without wrappers. In ""Annalen der Physik und Chemie. Hrsg. von J.C. Poggendorff"", Bd. 120, No.11. Pp. 337-512 a. 2 plates. (Entire issue offered). Clausius' paper: pp. 426-452. With titlepage to volume 120.‎

Reference : 45072

‎First appearance of one of Clausius' importent papers in which he gives further proofs of the Second Law of thermodynamics.""Clausius discovered that if he took the ratio of the heat content of a system and its absolute temperature, this ration would always increase in any process taken place in a closed system. (A closed system is one that loses no energy to the outside world and gains no energy from it.) With perfect efficiency, which is never realized in the real world, of course, the ratio would remain constant, but i would never, under any circumstances, decrease.""(Asimov). ‎