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a polarization device that determines the sugar content of solutions by measuring the angle of rotation of the plane of polarization of a light beam. The amount of rotation is proportional to the concentration of the solution. Sac-charimeters are used less frequently for measuring concentrations of other optically active substances.
Rotation in a saccharimeter is compensated, that is, the plane of polarization is rotated by an amount equal in magnitude and opposite in direction to the rotation produced by the solution. The compensator in a saccharimeter is a linearly movable quartz wedge (Figure 1) rather than the rotating analyzer of a polarimeter. The dependence of optical activity on the wavelength of the light, that is, the rotatory dispersion, of quartz and sugar are nearly identical. This circumstance allows the solution to be illuminated by white light when a quartz compensator is used in determining the concentration of sugar. The scale along which the compensating wedge travels is calibrated to give a direct reading of the percentage concentration of optically active substance in the solution. Compensation with sac-charimeters, as with polarimeters, involves an equalization of brightnesses of two halves of the field of view. Conditions for measuring sugar content with a saccharimeter have been standardized: the incident white light must first be filtered through a 1.5-cm layer of 6-percent potassium dichromate (K2Cr2O7) solution.
In many modern saccharimeters with polarizational modulation of light, the quartz compensator and scale are connected to a tracking system, and the rotation plane of polarization is compensated automatically.
REFERENCESLandsberg, G. S. Optika, 4th ed. (Obshchii kurs fiziki, vol. 3.) Moscow, 1957.
Shishlovskii, A. A. Prikladnaia fizicheskaia optika. Moscow, 1961.
Silin, P. M., and N. P. Silina. Khimicheskii kontrol’ sveklosakharnogo proizvodstva, 3rd ed. Moscow, 1960.