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Polarimeter
- Zeiss-Winkel
- Germany
- 252281
- Humboldt College; c.1950
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Use/History: This instrument uses a Nicol prism to produce
a beam of plane-polarized light (generally the sodium D line is
used as the monochromatic source), which then passes through a
sample tube, after which it is analyzed using a second Nicol prism
with a circular scale. In order to improve the readability and
accuracy of the instrument aother Nicol prism, called a Lippich
prism, is placed in front of the polarizer to create a split field
by introducing a few degree rotation for half of the light. The
instrument is now adjusted to match the two halves of the resulting
field. The polarimeter can be used to determine concentrations
of optically active substances as well as to aid in the identification
of unknown compounds.
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- The polarimeter was first used as a chemical instrument by
Jean Baptiste Biot around 1816.1 By the mid nineteenth
century they had achieved essentially modern form and they remained
essentially unchanged through the 1980's. This instrument was
in use by the HSU Chemistry department from 1953 until 1986.
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- Winkel was founded in 1857 by Rudolf Winkel and soon began
making student microscopes. In 1911 the name was changed to Winkel-Zeiss
when Zeiss acquired an interest in the company. Polarizing microscope
stands were a specialty. Around 1935 the name was changed to
Zeiss-Winkel. Winkel-Werke was still in production after WW2,
and remains the principle place of manufacture of West German
Zeiss microscope stands.2
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- Some contemporary/early descriptions of the polarimeter and
its use are provided below:
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- Description: The instrument is supported by two tapered
iron pillars, to give an overall height of 16" on an oval
cast iron base (6 1/2 x 13 1/2"), all in black crinkled
finish. The 4.75" readout circle is graduated in degrees,
with a vernier readout to 0.1° observed through a magnifier,
and illuminated via a small adjustable mirror. Original decal
(now removed): State of California/43919.
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- 1 Turner, Gerard L'E. Nineteenth Century Scientific
Instruments. Sotheby/U Cal., London/Berkeley (1983) p 222.
- 2 Bracegirdle, Brian. Notes on Modern Microscope
Manufacturers , Quekett Microscopical Club (1996) p 82-3.
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- © R. Paselk
- Last modified 15 August 2000
- All photographs © R. Paselk
