FREUNDLICH, HERBERT MAX FINLAY

(b. Berlin-Charlottenburg, Germany, 28 January 1880; d. Minneapolis, Minnesota, 30 March 1941),

colloid and interface science.

Freundlich was the older brother of Erwin Freundlich. At the age of nineteen he transferred from the University of Munich to that of Leipzig, in order to study chemistry under Wilhelm Ost-wald. After graduating in 1903, he remained as Ostwald’s chief assistant, later private assistant, until 1911, when he became associate professor of physical chemistry at the Technische Hochschule in Brunswick. During World War I, Freundlich’s knowledge of adsorption enabled him to find agents for gas masks. He was noticed by Fritz Haber, wartime chief of the Chemical Warfare Service, who found a post for him after the war at the Kaiser Wilhelm Institute for Physical Chemistry and Electrochemistry in Berlin—Dahlem. From 1919 until 1933 Freundlich’s laboratory was one of the world’s chief centers of research in colloid and interface science. He followed Haber’s example of linking his fundamental research to industrial processes (such as brewing and ore flotation) and to technically important systems (such as rubber, paint, oil, and detergents). In 1933 Freundlich left Germany to escape Nazi harassment. A five—year research appointment at University College, London, was created for him by Imperial Chemical Industries. He was elected an honorary fellow of the Chemical Society (1938) and a foreign member of the Royal Society (1939). At the end of his tenure in London he accepted a special research professorship at the University of Minnesota but served there for only two years before he died of a coronary thrombosis.

Freundlich’s most important contributions are on the flocculation of colloidal dispersions by electrolytes, particularly on the significance of the zeta potential and his demonstration that it is not the same as the ordinary electrode (Nernst) potential; on the viscosity and elasticity of colloidal dispersions and the phenomenon of thixotropy (a term he coined): on the effects of ultrasonic vibrations on colloidal stability; and on the biological applications of the principles of colloid science, many of which he himself had developed or amplified.

Freundlich was highly cultivated and an accomplished musician; his temperament combined the artist and the scientist. A lively and engaging conversationalist, he wrote books and papers that are models of organization and forceful exposition.

BIBLIOGRAPHY

I. Original Works. Freundlich’s major book is Kapillarchemie (Leipzig, 1909; 4th ed., 2 vols., 1930-1932). The English trans, of the 3rd ed. is Colloid and Capillary Chemistry (London. 1926); the 4th German ed., twice as long as the 3rd ed., has not yet been translated. A complete list of Freundlich’s 8 books and 243 papers is in the obituary notice by Donnan (see below).

II.Secondary Literature. Obituaries are F. G. Donnan, in Obituary Notices of Fellows of the Royal Society of London, 4 (1942). 27-50: R. A. Gortner and K. Sollner, in Science, 93 (1941), 414-416; H. S. Hat field, in Mature, 147 (1941). 568-569; E. K. Rideai. ibid., 568: and J. Traube. ibid., 148 (1941). 18.

Sydney Ross