Zwei unveröffentlichte Briefe von Gustav Magnus

“Two Unpublished Letters by Gustav Magnus” by Ralf Hahn (German language).—This essay presents two previously unpublished letters by Gustav Magnus and makes them available as rare documents of nineteenth-century scientific correspondence. Since no true Magnus Nachlass exists and no letters by him have survived in the archive of the German Physical Society, the two documents have particular evidentiary value. The first letter, dated June 20, 1838, is addressed to the chemist Richard Marchand and offers insight into collegial exchange, experimental practice, and the procurement of scientific instruments through the Berlin instrument maker Örtling; an incidental note on Henri Victor Regnault also points to current debates in chemistry. The second letter, dated April 6, 1862, was sent to Franz Gotthard Joseph Count von Schaffgotsch, chair of the Society of Friends of Natural Science in Berlin, and presents Magnus as a well-connected Berlin natural scientist who proposed John Tyndall and Thomas Graham as honorary members, emphasizing in particular Graham’s work on chemical separations by diffusion. At the same time, the letter makes clear the importance Magnus attached to his colloquium, which is regarded as the nucleus of the later German Physical Society.