‎"SMOLUCHOWSKI, MARIAN.‎
‎Beitrag zur Theorie der Opaleszenz von Gasen im Kritischen zustande.‎

‎Cracovie, Imprimerie de L'Université, 1911. 8vo. In the original printed wrappers. Offprint from ""Bulletin de L'Académie des Sciences de Cracovie"", Octobre 1911. Very fine and clean. Pp. (2), 493-502.‎

Reference : 48721

‎Offprint issue of Smoluchowski's second paper on the reasons behind the blue sky and how to reproduce it.""In 1910 Theodor Svedberg based his experiments on Smoluchowski's calculations, observing how many particles of a suspension can be seen in the field of vision of a microscope at a given time and experimentally confirming Smoluchowski's predictions to an astonishingly high degree Smoluchowski himself had previously proved the existence of fluctuations of density in a pure gas by demonstrating that they are responsible for the known but unexplained phenomenon of the opalescence of a gas at a critical state. His paper ""Teoria kinetyczna opalescencji gazów w stanie krytycznym"" (""kinetic Theory of Gas Opalescence at the Critical Stale"" 1907) shows why the critical point plays such an important role and states that the opalescence of pure gas also should be observable under normal conditions: ""Each of us has observed it innumerable times when admiring the blue of the sky or the glow of the rising sun."" Smoluchowski combined the theory of fluctuations with the results of Lord Rayleigh's researches on the blue of the sky"" his finding (Einstein also took part in the discussion) was that the blueness of the sky was caused by fluctuations in the density of the air. Smoiuchowski's laboratory production of sky blue closed the investigation to a certain extent."" (DSB).‎