Evening star. [volume] (Washington, D.C.) 1854-1972, 1906-08-24
MORE MICA USED.
Once Seen Chiefly in the Stove-Now
Employed to Insulate Electric Wires.

From the New York Sun.
There was a time when mica, or isinglass
as 1t was far more commonly called, was
familiar in one limited use in every house
hold In which there was parlor or a sit
ting-room stove, thin, transparent sheets
Of this mineral being set in the stove door.
Through the 'tsinglass," not destructible
when subjected to heat as glass would have
been. the glow of the fire within could be
seen.
With long use the mica might become
smoked up and Opaque, II might become
marred and broken. Then the head of the
household would get and set into the stove
door fresh isinglass from the stove dealers,
while the fragments of the old were very
probably turned over to the children, who
were likely to be surprised to find into how
much thinner sheets still the thin old
pieces from the stove door could be divided.
AS a matter of fact mica is Invisible into
sheets one two-thousandth of an inch in
thickness.
Now there are many who don't know mica
at all. not even as 1t is used in stoves,
people born and raised in houses that are
heated by steam, in which no stoves are
used for heating purposes; but while the
number of these Is large and all the time
growing. the number of people who yet use
stoves Is larger still; and so while mica
may have passed entirely out of the sight
and mind of many who once knew 1t in this
use. and in this use only, the preparation
Of 1t for stove use still constitutes regu-
lar branch of the mica trade; and thus one
of the old uses of mica still continues
The chief use to which mica is now put
Is one not dreamed of until within a COM
paratively few years, namely. as an insu-
1ating material in the construction of cleo
trical apparatus, for which purpose its use
is now general and constantly increasing,
and far larger than In any use to which it
had ever before been put.
Mica is used also for making chimneyS
for incandescent gas lamps placed where
they would be exposed to drafts, or out of
doors. subject TO the weather. Mica is used
TO make protectors for ornamental candle
shades. and il is used for making fancy
boxes and. In place of glass, for covering
the labels on drawers. as in a desk. Ground
up mica is now used In the manufacture
of lubricants and of fertilizers. and of dy-
Mantle. and in other forms 1t is used for
boiler coverings.
Mica was long used for windows and for
lanterns. and 1t is still used in lanterns
where such use would be advantageous. 1t
Is used in place of glass in spectacles worn
by stone and metal workers. and in miners
lamps. and II has been in the past or still
is put to various other. including ornamen-
tai. uses: but among It's various modern
uses the chief is in its application to cleo
trical machinery. For this the mica is cut
into hundreds of different shapes and sizes.
India is the chief source of the worlds
supply of mica. with Canada next, the
United States next, and Brazil and other
countries following. Mica, from one source
and another, ranges in color from white
or transparent, through various shades to
black.
In the formations In which II exists it IS
found in more or less scattering deposits,
or In pockets Its value depends. with re-
gard to the uses 10 which 1t may be put, on
It's color. its freedom from impurities and
the size OF the sheets that can be obtained
from II.
Now this anciently known mineral, for
many years put to varied though compare
lively limited uses. finds more extensive use
than ever in applications peculiarly modern.