Humboldt State University
Robert A. Paselk Scientific Instrument Museum
Spencer Lens Co.
Serial No. 36
Chemical Heritage Foundation
The Spencer Lens Company began selling an Abbe refractometer in about 1920. Catalog illustrations differed from the current instrument in having a tripod base. Spencer appears to be the most innovative of the three companies who introduced refractometers around the end of WW I, and whose instruments are illustrated in the catalog scan (Bausch & Lomb-8610, Spencer-8614, and Adam Hilger-8620). Thus the Spencer instrument uses a rack and pinion adjustment for the alidade and a sliding mount for the mirror to allow more efficient illumination. (Zeiss similarly modified their redesigned refractometer of c.1926, adding a rack and pinion drive, and putting the mirror on an arm.) The base was redesigned before1924, as illustrated in catalogs (e.g. Fisher, 1926)1, and as seen in the Spencer instrument in this exhibit. Spencer replaced the rack and pinion alidade drive with a clamp and slow motion screw around 1941, as shown in the Cenco 1941 catalog2 (the older rack and pinion form is still illustrated in the 1942 Eimer & Amend/Fisher catalog)3, and the 1953 AO Spencer instrument in this display. The catalog scan above is taken from the Arthur H. Thomas Co. catalog, Laboratory Apparatus and Reagents. Philadelphia (1921).
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 characteristics, 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.
The instrument stands 11.5" high in the closed, vertical position. The base is of cast iron with black japanned finish, some of which has come off to expose the iron in spots. The scale and readout arms are of brass. The control knobs are finished in laquered brass. The single-sided glass mirror is mounted on an adjustable dovetail slide. The scale is engraved on an inlaid German silver strip with scale divisions to the thousands place (nD 1.3001.710), and numbered to the hundreds place. A second scale, 0-84 is engraved to the right of the refractive index scale from 1.333 (pure water) to 1.499 (84% sugar). The operating temperature, 27.5° C. is engraved on the scale just above the 1.300 mark. The readout is viewed with an adjustable magnifier. A hairline engraved on a glass window affixed via a retaining ring to the prism alidade determines the index. The prism alidade has a rack and pinion fine adjustment. The refractometer telescope is heavy black enameled brass, with the Spencer/Buffalo/U.S.A. "lens" logo engraved on the arm over the serial number: 36. The Amici color compensating prism scale is finished in brushed nickel with black filled engraved divisions (0.0-6.0-0.0) and adjusted against a brushed nickel 0-10 vernier scale with a knurled wheel. The prism holder is finished in black enamel with polished nickel plated tubulatures for connecting to a circulating bath for temperature control. The instrument is missing the refractive index prism.
The instrument came in a fitted, mahogany-stained hardwood carrying case (14"h x 8"w x 7 5/8"d) and included a glass test-block (nD = 1.5229; 0.673" x 0.403" x 0.118", with one side and one end polished) in ivorine case (1 5/16" dia. by 3/8" h) made by the Whitehead & Hoag C., Newark, N. J. (written on side of lid), a dispersion table on heavy card-stock, and a user-made temperature calibration table. A users manual and dispersion charts from Bausch & Lomb were also included with the instrument, and may be accessed via links to the B&L Abbe refractometer.
1 Fisher Scientific Company. Fisher Scientific 81. Pittsburgh (1926).
2 Cenco. Cat J-141, General Catalog Laboratory Apparatus & Scientific Instruments. Chicago. (1941).
3 Eimer & Amend/Fisher Scientific Company Modern Laboratory Appliances 90. Pittsburgh/New York (1942, reprinted 1946)