26 Braun Corporation. Catalog No.8, Laboratory Instruments Apparatus and Supplies . Microscopes, Microtomes, Colorimeters, Optical Measuring Instruments and Accessories. The Abbe 56 is illustrated in both the 1950 catalogs of Adolf Frese and Cenco. 29 In this instrument the illuminated optical refractive index scale and the cross-hairs and boardeline are viewed alternately through a single eyepiece.
Illumination is via a built-in source.
The scales are enclosed and protected from the environment. This convenient and very popular instrument has continued in production, with slight modifications, to the present day. Library describes and illustrates Spencer's origianl refractometer with tripod base. This easy to read instrument is still sold under the Leica name. Rather, the story of this once key research instrument, which remains irreplaceable in the modern quality control and analysis laboratory, is a story of modification for convenience, cost, and the transition from practitioners to operators as its major clients.