The Pleasantville press. (Pleasantville, N.J.) 1912-1929, 1922-09-20
MICA NOW IN
GREAT DEMAH[
As Perfect InsuIator 1t Has I'm
portant and Varied Uses in
Electrical Industry.
FOUND IN THREE COUNTRIES
Possesses Combination of Special
Qualities Found In no Other
Substance-No Satisfactory
Substitute Found.

Washington.-Do you remember how
you used to sit before the old barrel
stove in the parlor, Or before that
s~.new-faIlgled' latrobe, watching the
glow of the CHEEKY winter fire through
the "isinglass windows? You ma.
think thai since the basement furnac,
has generally supplanted the trouble.
some pesky things the producers OF
''isinglass'' must have long since gopr
bankrupt but there's more demand
for 1t now than ever before, says the
United States bureau of mines.
Any way, 1t vas not isinglass at all
in the front of the W. Had it been.
it would have lasted as long as paper,
for isinglass is made of the air blad
ders Of certain fish and Is a soluble
.Ombustible substance. What reall,
was In the stove windows vas mica.
1ne Of the oldest of natural sub
stances, and which is now one of the
greatest boons In the electrical indus
try as a perfect insulator. So inpor-
tant is mica, in electrical goods, 1t Ii
declared, that many of the larger cleo
trical supply manufacturing companies
own and operate their own mica mines
Split Into Thin Plates.
Mica, says the bureau, includes II
group of several minerals character
lied by a perfect basal cleavage by
virtue Of which they may be split into
exceedingly thin plates.
H.. FL, Itl won
make wonderful finds of gold or
"silver's among the rock deposits near
the homestead? OF course, the
dreams of wealth vanished when you
found the silvery Oh golden flakes
were only mica. Such mica has no
commercial value; it is only when it
occurs In large deposits where it ap-
pears in Books" fairly free from de-
fects, varying in width and length
from a few inches to feet and up to
of value.
OF the several varieties of the min
eral only two are Of commercial
value, the "muscovite' or white mica,
and the 'phlogopite' or amber. India,
Canada and the United States are the
chief producers.
Has Special Qualities.
Mica possesses a combination of
special qualities which is found in no
other substance, consequently no sat
isfactory substitute has been found,
Chief among these qualities are elias
ticity, tOughness. ~fiexibility, trans
parency. ability to withstand exces.
sive heat and sudden changes of tenn
perature, high dielectric strength,
c~leavability and resistance to decom-
position.
An important use Of electrical mica
Is for interviewing between the cop
| per segments of commutators. Thin
films are used In vast numbers in con
densers for magnetos and in wireless
apparatus. AS sheets In greatly di.
versified shapes, or as washers and
tubes. mica is used extensively as an
insulator In dynamos and In various
| appliances, In fuse boxes, sockets, in
sulators, electric heaters, fiatirons, tel
ephones, etc. ass
As a heat-resisting, transparent me
dunn, sheet mica is still used in fur
mace sight holes, for heat screens
lamp chimneys, canopies and shades
particularly for gas nantes, also fol
military lanterns and lantern slides
It's ability to withstand strains ant
shocks, combined with its transpar
ency, has led to wide use In motor
goggles, spectacles, divers helmets
smoke helmets, compass cards, gage
fronts and In windows subject to
shock such as on the coming towers
Of battleships.