The Hope pioneer., 1922-10-05
MICA NOW IN
GREAT DEMAND
As Perfect InsuIator It 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
''new-fangled" latrobe, watching the
glow of the CHEEKY winter fire through
the "isinglass windows? You may
think that since the basement furnace
has generally supplanted the trouble
some pesky things the producers OF
'1singlass" must have long since gone
bankrupt; but there's more demand
for it now than ever before, says the
United States bureau Of mines.
Any way, it was not isinglass at all
in the front of the stove. 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 soluble
combustible substance. What really
was in the stove windows was mica,
one of the oldest of natural SUBJ
stances, and which Is now one Of the
greatest boons in the electrical indus
try as perfect insulator. So impor-
tant is mica, In electrical goods, it 10
declared, that many Of the larger elec-
trical supply manufacturing companies
own and operate their own mica mines.
Split Into Thin Plates.
Mica, says the bureau, includes q
group Of several minerals character
lied by perfect basal cleavage by
virtue Of which they may be split int
exceedingly thin plates.
How often as a youngster did you
make wonderful finds Of gold" or
'silver" among the rock deposits near
the homestead? OF course, the
dreams of wealth vanished when you
found the silvery or golden fakes
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 few inches to feet and up to
six inches or more in thickness 1t 10
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, flexibility, trans.
parency, ability to withstand exees-
sive heat and sudden changes Of tenn.
perature, high dielectric strength.
cleavability 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 d.
versifed shapes, or as washers and
tubes. mica is used extensively az IN
tnsulator In dynamos and In various
appliances, in fuse boxes, sockets, In
sulators, electric heaters, flatirons, tel.
ephones, etc.
As heat-resistin2 transparent me-
dium, sheet mica is still used in fur
mace sight holes, for heat screens,
lamp chimneys, canopies and shades,
particularly for gas mantles. also for
military lanterns and lantern slides.
Its ability to Withstand strains and
shocks, combined with it's transpar-
ency, has led to wide use in motor
goggles, spsctacles, divers helmets,
smoke helmets, compass cards, gage
fronts and in windows subject to
shock such as on the coming towers
Of hattloshins