Mineral Facts and Problems: 1960 Edition Page: 179
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A second method involves digesting pollucite
in a strong HC1 solution followed by filtration
to remove the siliceous residue. The filtrate
may then be treated by any one of several
different techniques including:
1. Antimony trichloride is added to crystal-
lize the cesium-antimony double chloride. The
double salt is dissolved in boiling water and
the antimony removed by precipitating it with
H2S.
2. The solution is saturated with ammonium
alum to crystallize hydrated cesium alum.
3. A solution of lead chloride containing
free chlorine is added to precipitate the double
lead-cesium chloride, which is then decomposed
with either aqueous hydrogen sulfide or am-
monium hydroxide.
The third method consists of mixing pollu-
cite with CaC12 and NH4C1, or other similar
compounds and roasting the mixture in a
:nickel crucible for one hour at 800-900. C.
The cooled mass is leached with water, and
the solution obtained is treated with H2SO4
and then with (NH4) 2C03 to precipitate the
calcium. Cesium is then precipitated as a
chloroplatinate by adding chloroplati nic acid
to the solution, or as a double chloride by
adding HCl followed by antimony trichloride.
Products contaminated with rubidium are
purified by taking advantage of the differences
in solubility of certain cesium and rubidium
salts.
REDUCTION OF COMPOUNDS TO METAL
Cesium metal has been prepared in many
ways. The method selected by American
Potash and Chemical Corp. is to reduce cesium
carbonate by reacting it at red heat with a
metal. The process yields high-purity cesium,
oxides of the metal reductant utilized, and
carbon. Alternate promising reduction :methods
include: Heating cesium hydroxide with
aluminum or magnesium in a stream of
hydrogen; reacting cesium chloride vapor with
heated calcium carbide (or calcium metal)
under vacuum; or vacuum reduction of cesium
fluoride with magnesium. Cesium metal has
been produced experimentally by electrolysis,
but this method has not proven economically
feasible to date. Because cesium is highly re-
active, the metal must be recovered under an
inert oil in a suitable receiver.
USES (7)
PHOTOMULTIPLIER TUBES
In this principal use of cesium, it is the
active agent for the conversion of light into
electricity. Sensitive to minutely varying in-
tensities of light, cesium will emit electrons
in response to the entire visible spectrum and
portions of the infrared and ultraviolet.INFRARED LAMPS
During World War II, an infrared lamp
employing cesium vapor was developed by the
Navy for "invisible signalling." A beam of
radiant energy was produced by a low-voltage
are discharge in cesium vapor. The lamp also
could be used as a searchlight.
INFRARED TELESCOPES AND BINOCULARS
The sniperscope and snooperscope were de-
veloped during World War II for viewing
objects in the dark and for receiving signals
from infrared lamps and now are used by
night watchmen, guards, and border patrols.
Infrared radiation, reflected from objects
warmer than their surroundings, enters the
telescope, strikes a cesium surface, and causes
a pattern of electron emission. The electrons
then impinge upon a fluorescent screen to
produce a visible image.
INFRARED SPECTROMETERS
Crystals of highly transparent cesium halides
may be used as prisms in infrared spectro-
meters, particularly when operating in the
longer wave length bands.
VACUUM TUBES
Cesium is one of several metals which will
absorb and retain residual gases in vacuum
tubes, thus maintaining the vacuum and en-
hancing the performance of the tube. A
cesium film deposited on the surface of
vacuum-tube filaments will increase the effi-
ciency of thermionic emission- from the fila-
ment.
SCINTILLATION COUNTERS
Cesium iodide and cesium bromide crystals
are used in some scintillation counters because
they emit electrons when exposed to nuclear
radiation.
FREQUENCY AND TIME STANDARDS
Cesium is used as a microwave frequency
standard in electronics and spectroscopy be-
cause of the long-time stability of the fre-
quency of emitted energy. The constant
energy emitted by cesium is also used by the
National Bureau of Standards to measure
and regulate time signals.
ANALYTICAL
Where quantities of material being analysed
are limited, it is essential to have reagents
which will give definite diagnostic results.
Cesium forms double salts of marked and
distinctive crystalline structure with many ele-
ments. Therefore, cesium salts are used in
qualitative determination of some elements
by chemical microscopy.179
CESIIUM
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United States. Bureau of Mines. Mineral Facts and Problems: 1960 Edition, report, 1960; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc38790/m1/187/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.