ZSIGMONDY, RICHARD ADOLF

(b. Vienna Austria, 1 April 1865;d. Göttingen, Germany, 24 September 1929)

colloidal chemistry.

Zsigmondy was a figure of paramount importance on colloid chemistry during the first quarter of the twentieth century. His receipt of the Nobel Prize in 1925, for invention of the ultramicroscope and his work on colloids was the first time this fledgling science had been so honored. In 1926 work by J. B. Perrin and Theodor Svedberg that followed directly from Zsigmondy’s achievement was recognized by the Nobel Prizes in physics and in chemistry, respectively. No Nobel Prize since then has been awarded for work solely in colloid chemistry.

Zsigmondy was the son of Adolf Zsigmondy, a dentist, and Irma von Szakmáry. He spent his childhood, his school years, and his first years as a university student in Vienna. He took his Ph.D. in organic chemistry at the University of Munich in 1890. With this, his activity in organic chemistry ended. Neither was he influenced by the great schools of physical chemistry developing in the Netherlands under van’t Hoff and at Leipzig under Ostwald. At Berlin, Zsigmondy worked on inorganic inclusions in glass with the physicist A.A. Kundt (1891-1892) and then, at Graz, as a lecturer on chemical technology at the Technische Hochschule until 1897, when he joined the Schott Glass Manufacturing Company in Jena. There he was concerned with colored and turbid glasses, and invented the famous Jena milk glass. Zsigmondy left industrial work in 1900 to pursue private research that led to the invention of the ultramicroscope and his classic studies on gold sols. His achievements during this period led to his being called to Göttingen as professor of inorganic chemistry in 1907.

Zsigmondy became interested in colloids through work with glasses that owed their color and opacity to colloidal inclusions. He soon recognized that the red fluids first prepared by Faraday through reduction of gold salts are largely analogues of ruby glasses, and he developed techniques for preparing them reproducibly. These gold sols became the model systems used in much of his work.

The presence of colloidal particles is apparent from the cone of scattered light known as the Tyndall beam. Zsigmondy’s great contribution was the invention of the ultramicroscope, which rendered the individual particles visible. In the ultramicro scope, ordinary illumination along the microscope’s axis is replaced by illumination perpendicular to the axis. With such dark-field illumination the individual particles are rendered luminous by the scattered light that reaches the eye of the observer, in much the same fashion that moving dust particles are illuminated in a sunbeam. This achievement had been rejected for particles much smaller than the resolving power of the microscope. Certainly the exaltation Zsigmondy experienced could hardly have been loss than that of any other intrepid explorer who reveals a new universe. “A swarm of dancing gnats in a sunbeam will give one an idea of the motion of the gold particles in the hydrosol of gold. They hop, dance, jump, dash together, and fly away from each other, so that it is difficult in the whirl to get one’s bearings.”

Although dark-field illumination had long been a recognized procedure in microscopy, many difficult technical problems remained. Zsigmondy was assisted by H. F. W. Siedentopf, a physicist with the Zeiss Company of Jena, in the design and construction of the apparatus. The company’s director, Ernst Abbe, placed the facilities of the Zeiss plant at their disposal even though Zsigmondy was not associated with the company. Indeed, this activity came at a time in his career when he had no professional attachment.

Much of Zsigmondy’s research was devoted to the investigation of gold sols and particularly purple of Cassius. Although it had been investigated by a number of noted chemists, no decision had been reached whether this peculiar preparation, valued as a glass paint, is a mixture or a compound. In 1898, Zsigmondy was able to show that it is a mixture of very small gold and stannic acid particles, and later directly confirmed the correctness of this finding with his ultramicroscope.

Zsigmondy investigated the color changes that occur in gold sols upon the addition of salts and studied the inhibition of these effects upon the addition of such protective agents as gelating and gumarabic. With the aid of the ultramicroscope, he demonstrated that the color changes reflected alteration of particle size due to coagulation and that the protective agents acted so as to inhibit the coagulation.

At Göttingen, Zsigmondy was occupied with ultrafiltration, which he developed as another use ful tool for the investigation of colloidal systems. He explored a broad range of substances, especially silica gels and soap gels.

A lover of nature and an avid mountain climber, Zsigmondy acquired an estate near Terlano, in the southern Tirol, to which he retreated frequently. He married Laura Luise Muiller, the daughter of Wilhelm Muller, in 1903; they had two daughters.

BIBLIOGRAPHY

Zsigmondy’s books include Zur Erkenntnis der Kolloide (Jena, 1905), translated by Jernome Alexander as Colloids and the Ultramicroscope (New York, 1909)’ kolloihemie; en Lehrbuch (Leipzig, 1912), 5th ed., 2vols. (Leipzig, 1925-1927), translated by E. B. Spear as The Chemistry of Colloids (New York, 1917); and Das kolloide Gold (Leipzig, 1925), written with P. A. Thiessen.

His memoirs and other writings are listed in Poggendorff, IV, 1695-1696; V, VI, 2971: for comprehensive bibliography of secondary literature, see VII a supp., 796.

Milton Kerker