Humboldt State University
Robert A. Paselk Scientific Instrument Museum
Bausch & Lomb
Ser. No. 5387
Chemical Heritage Foundation
Bausch & Lomb introduced an Abbe refractometer around 1919, according to an internal Carl Zeiss document.1 The currrent instrument uses the slow-motion screw introduced to B&L refractometers c.1926.2 It was most likely manufactured between 1937, when the patent marked on the instrument (2,080,841) was issued,3 and1941, when B&L began a new serial number sequence including letter designations.4 The B&L design is very similar to the contemporaneous Carl Zeiss design introduced c.1911, as well as that of Spencer.
The original B&L design remained unchanged with the exception of a few incremental changes, such as the slow motion screw in the current instrument, until a radical redesign, the "Abbe 56", using an enclosed, illuminated glass scale, in was introduced around 1949.5 The catalog scan is taken from the Braun Corp. Catalog No.34, Laboratory Instruments Apparatus and Supplies. Los Angeles. (1934).
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.
The instrument stands 12 1/5" high in the closed, vertical position.
The instrument is in its original light hardwood case (15 1/8"h x 8 1/2"d x 7 1/4"w) and has its original glass test block (nD = 1.5137; 0.798" x 0.466" x 0.146", with one side and one end polished). This exhibit also includes an early B&L Abbe refractometer manual and a set of B&L dispersion tables.
1 Entwurf zu einer Chronik der Abteilung Mess (An Outline of the History of the Measurement Division) is the following entry: 1919 Die amerikanische Firma Bausch & Lomb Rochester (USA) und die Firma Adam Hilger in London bauen nach den ihr durch den Krigesausgang übereigneten Pateten Zeiss-Geräte mit den Zeiss' schen Originalbezeicnumgen, z.B.: Refractometer nach Abbe; Refraktometer nach Pulfrich; Eintauchrefraktometer. (As a result of patents that were transferred because of the outcome of the war, the American firm Bausch & Lomb Rochester (USA) and the firm of Adam Hilger in London were able to produce instruments using original Zeiss [specifications/plans/designs] e.g. The Abbe Refractometer; The Pulfrich Refractometer; The Immersion Refractometer.) [translation courtesy B. Codispotti]
2 As shown in the Bausch & Lomb catalog: Microscopes, Microtomes, Colorimeters, Optical Measuring Instruments and Accessories. Bausch & Lomb Optical Company, New York (1926) pg 171.
3 A patent application for this instrument was filed in 1935 and issued (2,080,841) in 1937.
3 See Bracegirdle, Brian. Notes on Modern Microscope Manufacturers. Quekett Microscopical Club, Oxford (1996), for a list of serial number letters and their years of use.
5 The Abbe 56 is illustrated in: MacAlaster Bicknell Co. General Catalog of Laboratory Supplies and EquipmentCatalog M-E. New Haven (1949).