Humboldt State University
Robert A. Paselk Scientific Instrument Museum
Bausch & Lomb
Chemical Heritage Foundation
Hand refractometers are commonly used for determining concentrations of solutions from juices to battery acid. They are compact, easy to use and require only drops of sample. Early models, such as the one featured here were temperature sensitive, so include a thermometer and correction tables. More recent examples have an automatic compensation system built in, increasing their convenience. The catalog scan is courtesy of Van Waters & Rogers: Braun-Knecht-Heiman-Co. (Division of Van Waters & Rogers, Inc.) Catalog No 63, Laboratory Instruments Apparatus and Supplies. San Francisco. (1961).
Ernst Abbe described and illustrated a hand instrument in his original 1873 publication where he introduced the Abbe refractometer.2
The instrument came in its original box, with leather case, manual, bottle of 1-bromonapthalene and original glass test-block (nD = 1.46686; 0.801" x 0.311" x 0.155"; one side and one end are polished). A descriptionof the more general version of this instrument is available as a catalog scan from the 1950 Cenco catalog.
1 After 1941 B&L went to a letter system for serial numbers, with two letters preceeding the serial number. The first letter is the date letter, while the second is a class designation. Personal communication, Stuart Warter, California State University, Biology Dept., Long Beach State University (1998). The date letters are tabulated in Bracegirdle, Brian. Notes on Modern Microscope Manufacturers. Quekett Microscopical Club, Oxford (1996).
2 Abbe, E. Neue Apparate zur Bestimmung des Brechungs - und Zerstreuungsvermögens fester und flüssiger Körper. Mauke's Verlag, Jena (1874) Taffel: Fig. 8.