Zeiss Opton Refractometer

Description (Brief)
This refractometer was used in Stanley Cohen’s lab at Stanford University in his research on recombinant DNA. Refractometers measure how light changes velocity as it passes through a substance. This change is known as the refractive index and it is dependent on the composition of the substance being measured. In the Cohen lab, this refractometer was one of several techniques used to provide evidence that he and his research team had created a recombinant DNA molecule containing DNA from both a bacterium and a frog.
To conduct the analysis, Cohen separated out the molecule he assumed to be recombinant DNA and measured its refractive index. The index for the molecule fell between the known values for frog DNA and bacterial DNA, suggesting that the unknown DNA molecule was a mixture of the two.
For more information on the Cohen/Boyer experiments with recombinant DNA see object 1987.0757.01
“Section 9.4.2: Buoyant Density Centrifugation.” Smith, H., ed. The Molecular Biology of Plant Cells. Berkeley: University of California Press, 1977. http://ark.cdlib.org/ark:/13030/ft796nb4n2/
“Louisiana State University Macromolecular Studies Group How-To Guide: ABBE Zeiss Refractometer.” Pitot, Cécile. Accessed December 2012. http://macro.lsu.edu/howto/Abbe_refractometer.pdf
“Construction of Biologically Functional Bacterial Plasmids In Vitro.” Cohen, Stanley N., Annie C.Y. Chang, Herbert W. Boyer, Robert B. Helling. Proceedings of the National Academy of the Sciences. Vol. 70, No. 11. pp.3240–3244. November 1973.
“Replication and Transcription of Eukaryotic DNA in Escherichia coli.” Morrow, John F., Stanley N. Cohen, Annie C.Y. Chang, Herbert W. Boyer, Howard M. Goodman, Robert B. Helling. Proceedings of the National Academy of the Sciences. Vol. 71, No. 5. pp.1743–1747. May 1974.
Accession File
Currently not on view
date made
Cohen, Stanley N.
place made
associated place
United States: California, Stanford, Stanford
Physical Description
metal (overall material)
glass (overall material)
plastic (overall material)
average spatial: 21.7 cm x 33 cm x 16.7 cm; 8 17/32 in x 13 in x 6 9/16 in
overall: 12 in x 14 in x 6 in; 30.48 cm x 35.56 cm x 15.24 cm
ID Number
catalog number
accession number
serial number
Credit Line
Stanley N. Cohen, MD and Stanford University Medical Center
See more items in
Medicine and Science: Medicine
Science & Mathematics
Biotechnology and Genetics
Data Source
National Museum of American History


Add a comment about this object