saccharimeter (polaristrobometer)
Date: circa 1872
Inventory Number: DW0854a
Classification: Polarimeter
Subject:
Maker: Hermann & Pfister (1866 - 1881)
Cultural Region:
Place of Origin:
Bern,
Dimensions:
saccharimeter: 42 × 57.1 × 27.9 cm (16 9/16 × 22 1/2 × 11 in.)
box: 17 × 61.2 × 27.9 cm (6 11/16 × 24 1/8 × 11 in.)
Accessories: pine box; instruction manual; glass tubes (2); open-ended tube; gas lamp (DW0854b)
DescriptionThis saccharimeter differs from those of Soleil, Duboscq, Laurent, etc. because, instead of comparing the color of two semi-circles, it depends upon the disappearance of black interference fringes on a light background.
At one end is a polariscope, consisting of a magnifying objective lens, a diaphragm with crossed hairs, two sheets of calcspar 3mm thick, cut at 45-degree angles to the optical axis and crossed at right angles to their principal surfaces, and a Nicol analyzing prism. On the other end of the saccharimeter is a Nicol polarizing prism. Between them there is a space for the nickel tubes containing the sugar solution. There is a telescope running parallel that magnifies the reading on the vernier scale (which measures the angle that the analyzer is rotated). The instrument was designed to be used with a sodium lamp giving off a homogeneous yellow light (see DW0854b). The instrument is stored in a box when not in use.
A complete description is found on the following website.
At one end is a polariscope, consisting of a magnifying objective lens, a diaphragm with crossed hairs, two sheets of calcspar 3mm thick, cut at 45-degree angles to the optical axis and crossed at right angles to their principal surfaces, and a Nicol analyzing prism. On the other end of the saccharimeter is a Nicol polarizing prism. Between them there is a space for the nickel tubes containing the sugar solution. There is a telescope running parallel that magnifies the reading on the vernier scale (which measures the angle that the analyzer is rotated). The instrument was designed to be used with a sodium lamp giving off a homogeneous yellow light (see DW0854b). The instrument is stored in a box when not in use.
A complete description is found on the following website.
Signedon diaphragm, script: No. 445 / Hermann & Pfister / Bern
FunctionThis instrument is a type of polarimeter invented by Wild in 1864. A saccharimeter is a polarimeter adapted for use with light source (sun or artificial, monochromatic or not), and it measures the optical activity of sugar solutions. The analyzer and polarizer (which are usually prisms) would be aligned such that no light passed through. Then the liquid substance was placed in between them, in a glass vial, and then put within the long tube seen on the picture. Light passing through the liquid creates fringes. The analyzer, close to the eyepiece, would be rotated until the fringes disappeared, and that angle would characterize the optical activity of the substance.
