Dickinson, Roscoe Gilkey

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Dickinson, Roscoe Gilkey

(b. Brewer, Maine, 10 June 1894; d. Pasadena, California, 13 July 1945)

physical chemistry, X rays, crystal structure.

Dickinson’s father, George E. M. Dickinson, was a violin teacher and director of music for the Hyde Park, Massachusetts, city schools; his mother’s maiden name was Georgie Simmons. He attended grammar school and high school in Hyde Park and then studied chemical engineering at the Massachusetts Institute of Technology, where he received the B.S. degree in 1915. After two years of graduate work there he was appointed instructor at the California Institute of Technology (called Throop College of Technology until 1918). In 1920 he became the first recipient of the Ph.D. degree from this institute. He remained there all his life; at the time of his death he was professor of physical chemistry and acting dean of graduate studies.

As a graduate student Dickinson became familiar with the technique of determining the atomic structure of crystals by the X-ray diffraction method through his contact with C. Lalor Burdick and James H. Ellis, who carried out, in Pasadena, the first crystal-structure determination made in the western hemisphere. At that time the lack of quantitative information about the interaction of X rays and crystals made the task of the crystal-structure investigator a difficult one. The field was, however, especially well suited to Dickinson, whose outstanding characteristics were great clarity of thought, a mastery of the processes of logical deduction, and meticulous care in his experimental work and in the analysis of data. He carried out many crystal-structure determinations, all of which have been found to be reliable to within the limits of error that he assigned. He determined the structures of a number of crystals containing inorganic complexes, including the hexachlorostannates, the tetrachloropalladites and tetrachloroplatinites, and the tetracyanide complexes of zinc and mercury. His determination (with one of his students, A. L. Raymond) of the structure of hexamethylenetetramine was the first structure determination ever made of a molecule of an organic compound. In a decade he developed the leading American school of X rays and crystal structure.

During the last twenty years of his life Dickinson and his students carried on many researches in other fields, including photochemistry, chemical kinetics, Raman spectroscopy, the properties of neutrons, and the use of radioactive indicators in studying chemical reactions. Through this, as well as through his work on crystal structure, he contributed significantly to the development of the California Institute of Technology.