Humboldt State University
Robert A. Paselk Scientific Instrument Museum
"New" Abbe Refractometer
Chemical Heritage Foundation
This instrument, illustrates the features of the final Zeiss Abbe refractometer design, the so-called "neues Abbe-Refractometer" or new Abbe-refractometer.This new design was manufactured by Carl Zeiss Oberkochen from 1950 (initially as Zeiss-Opton, view an image of the logo) until 1990, when Zeiss ceased production of refractometers.2 Similar instruments,apparently inpired by the original Zeiss design, are still being manufactured and sold by various companies. Compared to the previous Zeiss design (see the 1926 example in this exhibit), the instrument now has an optical readout of the refractive index through the eyepiece and a horizontal prism surface, both making the instrument more convenient for the user. Zeiss introduced their "new design" in 1950.3 According to The Zeiss Historica Society.4 Zeiss scientists in West Germany designed new instruments from scratch following "denazification" after WW II. Though Zeiss had a tradition of optical reading in refractometer in their sugar and butter refractometers, the loss of their prototypes etc. to East Germany apparently inspired this new and very elegant design. The new design also has clear precedent in the 1935 butter refractometer, as seen in the illustration on the manual cover. Perhaps the slightly preceeding new Abbe 56 from Bausch & Lomb also influenced them. Certainly the Bausch & Lomb 3L seems to owe some of its features (e.g. the horizontal prism, new optical readout) to the new Zeiss design. 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).
The Abbe refractometer provides a quick and easy means for determining refractive index and dispersion of liquids and solids. Its most common use is the determination of the concentrations of solutions. A brief essay, The Chemical Refractometer, describes the charecteristics, design, and use of these instruments. A detailed history, The Evolution of the Abbe Refractometer, traces the development of this valuable instrument to around 1980.
By 1980 the Zeiss instrument, as indicated in the Fisher catalog scan [Fisher Scientific Company. Fisher Scientific 81: apparatus, chemicals, furniture and supplies for industrial, clinical, college and government laboratories. Pittsburgh (1980)], had a reputation for the "best" as reflected in its high relative cost of $2831 vs. $1750 for a B&L Abbe 3L and $1525 for a Fisher Abbe, while the AO Digital Abbe was $2375.
The instrument stands 22.6cm high to the top of the eyepiece (set at 0). The cast aluminum (?) base is 12cm diameter. The instrument has a brass body, originally finished in black 'japanned' enamel, with exposed metal parts finished with a satin-chrome plate. As seen in the photographs, the instrument has significant cosmetic damage, with large patches of enamel lost to chemical stripping in the instruments long use. In the photograph of the instrument from the right side, the large knob at the bottom adjusts the refractive index, while the smaller knob above it, just behind and above the prism mount, adjusts the Amici prism compensator, and is graduated incrementally from 0-60-0, numbered decadally. The apparent knob at the top is actually a cover for an adjustment screw. Looking at the photograph of the instrument from the left side, the labels point out the knob on the left side of the instrumentwhich locks the illuminating prism in the closed position, and the light pipe which illuminates the optical refractive index scale (the pipe can be covered by a finger when determining the refractive index). The white-backed magnifying thermometer (mercury-bulb broken off) is graduated from -5°C by 50°C by one-degree increments and numbered every 10 degrees.
The instrument has its original fitted Oak case (31cm h x 15cm w x 20cm d), see the image of the closed Oak case, with an apparently original thermometer (broken) in a metal jacket. There are places - for the thermometer near the refractometer eyepiece, for a bottle of bromophenolnapthol (missing) on the inside of the door and a test-block (missing) at the base of the case - all may be seen in the image of the refractometer in its case. An image of the tag on gthe inside door of the case is also available.
1 As noted below the neues refractometer was introduced in 1950, while according to the Carl Zeiss company history, the West German Zeiss company operated as Zeiss-Opton beginning in October 1946 and was taken over by the reformed Carl Zeiss in October 1953 (http://www.zeiss.com/C12567A100537AB9/Contents-Frame/63125BAC5434D55DC1256DB900446D61) downloaded 8/24/2010.
2 Personal communication (2003), Dr. Wolfgang Wimmer, Archivar, Carl Zeiss Jena GMBH.
3The Carl Zeiss document Reifezeit für High-Tech, under the column "Refraktometrie" has the following listing: 1950 neues Abbe-Refractometer.