Jaeger, Frans Maurits

(b. The Hague, Netherlands, 11 May 1877; Haren, near Groningen, Netherlands, 2 March 1945)

crystallography, physical chemistry.

Jaeger was the oldest of three sons of an officer who left the army at twenty-eight and then taught mathematics at the Gymnasium in The Hague. After completing his primary and secondary education in his native town, Jaeger entered the nearby University of Leiden in 1895, working as a part-time assistant at the geological museum. After his final examination in 1900 he obtained a stipend for two years of study at the University of Berlin, where he obtained practical experience in the laboratories of E. Fischer, E. Warburg, and J. F. C. Klein. While in Berlin he married the sister of his classmate B. R. de Bruijn. He began to teach chemistry in the fall of 1902 at a secondary school in Zaandam, near Amsterdam. On 9 October 1903 he obtained his Ph.D. from Leiden University with a thesis suggested by his promoter, A. P. Franchimont, entitled Kristallografische en moleculaire symmetrie van plaatsings-isomere benzolderivaten.

Under the supervision of H. W. Bakhuis Roozeboom, the successor to J. H. van’t Hoff, Jaeger continued his studies at the municipal university in Amsterdam. On the recommendation of Roozeboom, he was allowed to teach as privaat-docent at the university while retaining his salaried position at Zaandam. In 1908 he was appointed lecturer, and the following year professor, of physical chemistry at the University of Groningen; he held this position until his dismissal by the Nazis in November 1944. One of his first tasks was to plan a new chemical laboratory to replace the one destroyed by fire in 1906.

Through his friend H. R. Kruyt, professor of colloid science at the University of Utrecht, Jaeger became acquainted with A. L. Day, director of the Geophysical Division of the Carnegie Institution of Washington. He spent one semester (September 1910-March 1911) with Day and thereby learned how to equip his new laboratory (opened in 1912) for the study of silicates and other materials with high melting points. In 1929 Jaeger returned to the United States as nonresident George Fisher Baker lecturer at Cornell University, where he gave a summary of his laboratory work from 1912 to 1929.

Throughout his active life as a scientist Jaeger was fascinated by the study of crystals. His first book on this topic, Lectures on the Principle of Symmetry and Its Applications in All Natural Sciences, was published in Amsterdam in 1917. Jaeger’s most important work was his study of molten salts and silicates at extremely high temperatures. It involved the determination of viscosity, surface tension, conductivity, and specific heat at temperatures ranging from&50° to 1,600°C. Jaeger’s bent for writing on the history of chemistry was probably inherited from his father who wrote in his spare time under the pseudonym of Maurits Smit. This hobby became a welcome necessity during the two world wars, when laboratory work was limited or entirely halted, particularly after the German invasion of Holland in 1940. Most of Jaeger’s contributions to science are recorded in English in Proceedings. K. Nederlandse akademie van wetenschappen, of which academy he became a member in 1915.

BIBLIOGRAPHY

I. Original Works. Jaeger’s writings include Anleitung zur Ausführung exakter physiko-chemischer Messungen bei höheren Temperaturen (Groningen, 1913); and the Geoerge Fisher Baker Nonresident Lecturership in chemistry at Cornell University, VII (New York 1930); I, “Spatial Arrangements of Atomic Systems and Optical Activity” II. “Methods, Results and Problems of Precise Measurements at High Temperatures” III, “The Construction and Structure of Ultramarines”.

II. Secondary Literature A résumé, by his collaborators, of 25 years of Jaeger’s activity as profesasor appeared in Chemisch weekbland, 31 (1934), 182-212; an obituary by his colleague J. M. Bijvoet is in Jaarboek der K. Nederlandsche asademie van wetenschappen (1945).

Henry S. van Klooster