Photoelectric colorimetry was a hot topic in the mid-1930s when Arnoldus Goudsmit Jr. and William Henry Summerson described a photoelectric colorimeter of their own design. As graduate students at the Cornell University Medical College, Goudsmit and Summerson knew that the "progress of analytical biochemistry in the past 30 years has been closely associated with the use of the colorimeter as a measuring instrument," and they believed that an instrument that used standard photocells to measure the intensity of light would give more reliable results than one that depended on the eyesight of individual people.
Summerson applied for a patent in 1938, one year after receiving a PhD in biochemistry. The Klett Manufacturing Co. of New York began marketing this instrument in 1939, noting that it would "bring the convenience, speed, accuracy and other advantages of photoelectric colorimetry to the laboratory" and provide "analytical precision in an instrument that is simple and easy to operate." The original model was still available in 1965; the same in a slightly different housing could still be had in 1974.
The inscription on this example reads "KLETT-SUMMERSON / PHOTELECTRIC COLORIMETER / PAT. NO. 2193437-1940 / KLETT MFG. CO. / N.Y. U.S.A. / MODEL 900.3 / SERIAL 12 246 / VOLTS 115 / MAX. WATTS 100." The instrument was made after the issuance of Summerson's patent (#2,193,437) in 1940. The National Institutes of Health transferred it to the Smithsonian in 1980.
Ref: A. Goudsmit Jr., and W. H. Summerson, "A Variable Layer Photoelectric Comparison Photometer," Journal of Biological Chemistry 111 (1935): 421-433.
Summerson, "A Simplified Test-Tube Photoelectric Colorimeter, and the Use of the Photoelectric Colorimeter in Colorimetric Analysis," Journal of Biological Chemistry 130 (1939): 149-166.
Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.