Richard Adolf Zsigmondy
Richard Zsigmondy received the 1925 Nobel Prize in chemistry for his elucidation of the nature of colloidal suspensions. With Henry Siedentopf (1872–1940), he invented, used, and promoted the ultramicroscope. Zsigmondy and others used ultramicroscopic studies of colloidal suspensions to convince influential skeptics that molecules are real and that matter is discontinuous at the molecular level.
Zsigmondy was born in Vienna, Austria, the fourth child of Irma von Szakmáry and Adolf Zsigmondy. Both parents encouraged chemical and physical experiments at home for their children. Young Zsigmondy studied chemistry in Vienna and Munich. Between 1883 and 1887 he worked at a glass factory in Bohemia, investigating luster and color in glasses. The University of Erlangen awarded him a doctorate degree in 1889. From 1890 to 1892 he worked in Berlin with August Kundt (1839–1894), studying the phenomenon of colors appearing on porcelain when suspensions of colloidal gold were applied before firing.
Beginning in 1893, Zsigmondy taught chemical technology and at the same time continued his own research on colloidal gold at the Technische Hochshule in Graz. He formed associations with glassmakers at the Schott Glass Company in Jena. The Schott Glass Company was famous for its making of glass scientific apparatus, including optical instruments. Zsigmondy left Graz in 1897 and became part of the Schott laboratory, where he conducted systematic investigations of colored glasses as colloidal systems.
Zsigmondy needed new types of optical instruments for his experiments. At the Schott laboratory, he had a hand in designing and constructing such instrumentation. Siedentopf joined the laboratory in 1899, and there he and Zsigmondy created the ultramicroscope. The Carl Zeiss Company, also in Jena, manufactured and sold the instruments.
Just as individual dust particles suspended in air can be seen and counted in a beam of sunlight, so individual colloidal particles can be seen and counted when a sample is illuminated in an ultramicroscope. In each case, the best viewing direction is perpendicular to the direction of illumination. Zsigmondy used aqueous solutions of colloidal gold as model systems. He prepared colloidal gold by reducing solutions of gold chloride with formaldehyde . Knowing the mass of gold in a known volume of solution and using the ultramicroscope to count the number of colloidal particles in that volume, he determined the molecular weight of the gold colloid.
Zsigmondy extended his observations to a wide range of important colloids—proteins, soaps, dyestuffs, clays, and polysaccharides. He was an influential leader in colloid physical chemistry throughout the first quarter of the twentieth century.
Nye, Mary Jo (1972). Molecular Reality: A Perspective on the Scientific Work of Jean Perrin. New York: American Elsevier.
Zsigmondy, Richard (1909). Colloids and the Ultramicroscope: A Manual of Colloid Chemistry and Ultramicroscopy, tr. Jerome Alexander. New York: Wiley.
Zsigmondy, Richard (1917). The Chemistry of Colloids, tr. Elwood B. Spear. New York: Wiley.