The Saccharimeter is a device for measuring the rotation of the plane of polarization of liquids. Polarized light produced by the Nicol prism on the right-hand side of the apparatus travels through the empty glass cell, and a second Nicol prism on the left-hand side is rotated until the light (usually the yellow light from a sodium lamp) is extinguished. The liquid sample is placed in the cell, and the amount by which the Nicol prism has to be rotated to get extinction once more is noted. This angle is a linear function of the concentration of the sample. The original work was done by Jean-Baptiste Biot (1774-1862) in the 1830s. 

    Saccharimeters get their name from their use in 

distinguishing between sugars which produce right-handed rotation of the plane of polarization (dextrose) and left-handed rotation (levulose or fructose). They were basic instruments in chemistry laboratories, and are not very often found in physics laboratories. The instrument above is at Kenyon College, and dates from the end of the 19th century. I have used it a number of times in upper-division optics laboratories, perhaps because it was available.

   The saccharimeters below, all by Duboscq of Paris, are in the collection of the United States Military Academy. The middle one is an 1845 design by the French instrument manufacturer Jean-Baptiste-François Soliel (1798-1878), whose business was taken over in 1849 by his former apprentice and son-in-law Jules Duboscq. The transverse white mechanism on the right-hand side is a pair of quartz wedges, one cut to rotate plane polarized light to the right and the other one to the left. These are slid back and forth until the rotation caused by the liquid is cancelled.
   This handsome Soleil-type saccharimeter is in the Garland Collection of Classical Physics Apparatus at Vanderbilt University. It was bought from the firm of J. Duboscq of Paris about 1875. 

   The eyepiece is missing, but the apparatus is otherwise complete. The right-hand side of the mechanism can be slid back and forth to accomodate sample tubes of various lengths. 

   The 1885 Duboscq catalogue listed this apparatus at 250 francs (about $50).

   This small, unmarked saccharimeter probably dates from the early years of the 20th century. The aluminum handle used to rotate the Nicol prism assembly is clearly not original.

   The apparatus is in the Greenslade Collection.

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