b. Vienna, April 1, 1865, d. Goettingen (Germany), Sept. 23, 1929, chemist, Nobel Prize laureate; brother of Emil Zsigmondy. Outstanding researcher in the fields of colloid chemistry and microscopy; awarded the Nobel Prize in 1926 (for 1925) for proving the heterogeneous nature of colloids and for applying new research methods which today form the basis of colloid chemistry. Private assistant in Munich in 1889 and in Berlin from 1890 to 1892; 1893 assistant at Graz University of Technology, where he wrote his habilitation. At that time he already dealt with gold ruby glass and ceramic colours in his search for glass staining methods. While employed at the Schott glassworks in Jena from 1897 to 1900, he developed a number of different kinds of stained glass, as well as the famous Jena milk glass, and took out various technological patents. From 1900 to 1907 lived as a private scientist in Jena before he retired with his whole family to his home at Terlago near Trento. From 1908 to 1929 was Professor at Goettingen University and head of its Department of Inorganic Chemistry.
While living in Jena, Z. carried out his first basic research in the field of colloid chemistry. Together with the physicist H. F. W. Siedentopf he invented an ultramicroscope based on the dark contrast method. By way of improving this microscope, he developed the immersion ultramicroscope in 1913, with which he was able to make particles the size of a millionth of a millimetre visible. In addition, Z. introduced a system of particles classified according to their size which can be found in fluids and in solid matter (e.g. in precious stones). He called them microns, submicrons and amicrons (disperse particles too small to be seen even under his ultramicroscope). To make even amicrons visible under the microscope, he developed a special technique called silver enhancement.
In Goettingen he revolutionized chemical research with his findings on the processes at work during the coagulation of colloids (the transition from fluid into colloidal matter). In 1918 invented the membrane filter and the ultrafilter. His studies strongly influenced the research carried out in the fields of biology and medicine, since they showed that protoplasm displayed the same characteristics and reactions as colloids.
Publications#Zur Erkenntnis der Kolloide, 1905; Kolloidchemie mit bes. Beruecksichtigung der anorgan. Kolloide, 1907; Kolloidchemie, 1912 (5th ed., 2 parts, 1925/1927); Ueber die technische Gasanalyse, 1920 (with F. Jander); Ueber das kolloide Gold, 1925 (with A. Thiessen). - Festschrift, 1925.
Literature#F. G. Smekal, Oe. Nobelpreistraeger, 1961; W. Martin, Verzeichnis der Nobelpreistraeger 1901-1987, 21988.