Use/History: The Beckmann thermometer was invented
by Ernest Otto Beckmann (1853-1923), also noted for the Beckmann
transformation in organic chemistry, as a result of his work
with oximes. His interest in the physical properties of these
molecules lead him to invent a number of ingenious apparatus
for measuring colligative properties based on the theoretical
work of Francois Marie Raoult (1830-1901). He began publishing
this work around 1888. Beckmann developed the differential thermometer
bearing his name, which could accurately measure temperatures
to about 0.001° C, in order to measure the very small temperature
changes found in boiling point and freezing point determinations
of molecular weight.
Some early descriptions of the Beckmann thermometer and its
use are provided below:
Description: The thermometer is a Cenco model No.
19410 (made in Germany). It is 57.5 cm in overall length, with
a 35.5 cm long milk glass baking inside the large tube. There
is a nickel cap on top made of straight tubing to which a flat,
knurled-edge top with a small turned knob in the center is soldered.
The thermometer is graduated from -0.1 to 6.1 °C by 1/100
°C on the main scale, and from -9 to 144 °C by single
degrees on the upper "setting" scale. The upper scale
has every 10 degrees numbered (obviously by hand), while the
main scale is numbered every 0.2° with larger numbering at
each degree.
Research: The metal cap appears to be of an early
style, not shown in the listings for 1976, 1960 (J-300, pg 257),
1950 (J-150, pg 367), or 1941 (J-141, pg 380) Cenco catalogs,
even though the same model number is used (19410). A similar
cap style does show up in the 1927 (C-227) Cenco catalog (p 664),
but it is given a different catalog number (13522)
References:
Gascoigne, Robert Mortimer. A Chronology of the History
of Science, 1450-1900. Garland Publishing, Inc. New York
(1987) pg. 137
Gienapp, Ruth Ann. "Beckmann, Ernest Otto" in Dictionary
of Scientific Biography, vol. 1 (Charles Coulston Gillispie,
editor), Charles Scribner's Sons. New York (1970) pg. 553.
Laidler, Keith J. The World of Physical Chemistry.
Oxford Univ. Press. Oxford (1993) pg. 124.
