Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-08-17
SeIeninm i'm Mdustyr.


for commercial use, and the annual pEoduc-
ton Is speeding up. 1t il estimated that the
United States alone can turn out from 100000
TO 4S0.OOo pounds annually. as by-pFoducts
or other industries.
The real growth of the selenium industry
began In 1921 when $4,000 pounds were
produced. 1t has gained each year, and 1927,
the last year for which complete figures are
available. showed 2s4, 500 pounds used. The
rubber industry seems 10 offer the largest
use at present, and it is believed that re-
search win add greatly to its employment in
that line.
Selenium IN metallic form has long been
characterised by its unique action toward
light Its conduetivity Of an electric current
varies so greatly when brought from the
dark into the light that this peculiar prop
eFty varying Is 1t does In direct proportion
to the intensity of the light has caused the
development Of the selenium cell.
The selenium cell has received considerable
attention for many years. It's action toward
light and the resulting effect upon its re-
sistance was discovered by w. Smith In 1878.
These cells have numerous Industrial ap-
plieations, such as in the optophone, an ap-
paFApes 1nNentsd ~ 0ALne by Whlch Inc pnn0
may read ordinary type by ear: the self
lighting buoy: control apparatus for chimney
draft: subway, tunnel and vehicuar tube
ventilation control; control of progress in
sulphuric acid manufacture by the contact
process. and various other minor uses.
The selenium CELL however, can be used
only where the recovery of its absolute re-
Sistance to change from light to dark does
not have to be instantaneous. Where this
change must be instantaneous other cells, such
as the potassium photoelectric cell, or the
copper oxide cell, are used.
During recent years selenium cells have
been considerably improved and several makes
now on the market, where the inertia has
been reduced to a minimum. The possibility
of using Selenium cells for television purposes
is again being investigated.
Another unusual use of selenium is that for
fameproOfing electric switchboard cables. The
cables behind the switchboaTds Of generating
and distributing stations apt to accumu-
late dust and this occasionally produces short
circuits. which, when heavy currents are car
ried, may set fire to parts of the cable COW
ering. Gables treated with thin layer Of
metallic seleniun, however, are made fame
proof to remarkable extent.
The principal use of selenium and its COM
pounds at present is as decolorizer in the
glass industry and for the production of ruby
glass Sailing signals, auto tail-hghts railroad
signal lights, etc. and ruby gia1es in the
ceramic industry. Its principal in the
glass industry is to offset the greenish tint
which is caused by traces of iron in the glass
sand e#e
In the manufacture of ruby glass selenium
is used extensively, either in the form Of the
element or as the Selenite in conjunction with
reducing agent, such as arsenious oxide.
Red lead and gold chloride. however, also are
used Tor the same purpose.
Another use for selenium which may be-
come Of importance is as solvent. II has
been stated that selenium in the form of
selenium oxychloride is one of the most pow
erfu solvents known: Synthetic phenolic
resins, such as redmanol or bakelite, which
are used for many industrial purposes and
have hitherto been regarded as totally in
soluble, are now readily dissolved by Selenium
oxychloride.
Considerable research work has been car
Tled on concerning the use Of Selenium q
Vulcani2ing and accelerating agent in the
manufacture Of rubber. The use of this min
eral In the rubber industry is increasing, and
1t is estimated that in 1929 about 100000
pounds of selenium were used in that work
The potential demand for selenium, If its use
Is adopted by the entire rubber industry, is
far greater than the copper refineries can
furnish.
Fine-drawn wire Of selenium. made by the
Taylor process is finding some commercial
applications. This wire may be drawn to
diametefS as small as one nnilimeter to one
naicron.
Selenium, although fairly widely distributed
is not very abundant in nature. It is found
associated with its sister element, sulphur
The sulphides of the heavy metals likewise
are often accompanied by selenium and
tellurium, presumably In the form of selenides
and tellurides. Certain iron pyrites, such as
that from Greece, Spain, Germany and from
the Scandinavian Peninsula, contain some
selenium. Both the German and the Scandi-
naVian pyrites yield selenium The selenium
is not of course, the object of the metal-
lurgical operations, but it IS recovered com.
mercially with nickel and molygdenUm as by
nrodlncks from the srneltinn nnaratinnS nuhicla