‎"CLAUSIUS, R. (RUDOLF). - RADIANT HEAT AND THE SECOND THERMODYNAMIC LAW.‎
‎Ueber die Concentration von Wärme- und Lichtstrahlen und die gränzen ihrer Wirkung. (Vorgetragen in der Züricher naturforschenden Gesellschaft am 22. Juni 1863).‎

‎Leipzig, Johann Ambrosius Barth, 1864. Without wrappers. In ""Annalen der Physik und Chemie. Hrsg. von J.C. Poggendorff"", Bd. 121, No 1. Pp. 1-192 a. 2 plates. (Entire issue offered). Clausius' paper: pp. 1-44. With titlepage to volume 121.‎

Reference : 45076

‎First apperance of an importent paper in which Clausius shows that radiant heat is not an exception to the Second Law of Thermodynamics"" - it is and answer to some suggested counter-entropic processes.""In 1864 he answered it in a long and detailled paper in which he made use of Kirchhoff's recent work on heat or blackbody radiation. Clausius' conclusion was unambiguous: radiant heat was no exception to the second law and it could not provide a means for escaping the heat death.""(Helge Kragh ""Matter and Spirit in the universe.."", p. 48.‎