Omaha daily bee., 1893-08-16
MICA Is THE STUFF.
In These Days the world Could Hardly
Worry Along without 1t.

In These Days the world Could Hardly
Worry Along without 1t.
Mica fills the interstices of modern
progress. A few decades ago we were
seeking practical use and market for the
output of mica mines already found
now we are seeking new mines to supply
the multifarious uses to which mica can
be applied. Thus the law of necessity
changes in its relation to all things.
Mica is now as essential to the various
uses of electricity as this great force is
necessary to human progress. In all APP
pliances for electrical lighting and
power, says the Chicago Inter Ocean,
the most important reciprocal agent en-
tering into their mechanism is mica
All armatures are built up with its in
sulation, whether for dynamos, motors,
generators or transformers. Without
its use as an insulation the core of the
armature would burn out with FASH
but by placing sheets of mica between
the thin sheets of iron, which are Sc
cured to the shaft that runs through the
drum of the armature, insulation be-
comes perfect. Thus armatures OF even
the largest generators can be run Tor
twenty-four continuous hours without
heating them more than 500 Fahren-
heit above the temperature of the sur
rounding air. BY this use of mica the
lines of force are dissipated, put do not
lose any of their electrical energy.
In electrical safety appliances mica also
performs an important part as an in
sulator. To its infusible and indestruct-
ible nature much of the success OF the
rheostat can be ascribed. This wonder
full mechanism, which is applied as
motor starter, governor of speed, re-
lt,,f itph md nl1
switch. is absolutely fire-proof, and can
be subjected to red heat without
mechanical injury. This is rendered
possible by making the resistance OF
thin plates of iron packed closely to
gether, but separated by mica.
Thus the lines of force operate on the
same principle. as in the armature
Aside from these important uses of mica
in electrical apparatus, it is also applied
20 q thousand minor ones, which make it
the constant and willing servant of the
great power that man has turned to in
telligent subjugation.
Mica Is also an important factor in
many branches of manufacture and art.
Owing to its peculiar elasticity and
| toughness, qualities in which it is not
excelled by anything natural or arti
| fetal, it is used as an absorbant of nitro7
| glycerine, and when so used explosions
| by percussion are rendered almost i'm
| possible, while at the same time nothing
| is taken from the energy of the nitro
| glycerine when exploded by Eliminates
or similar device. For such purpose
the plumose mica is used, or that in
which the scales are arranged in feath-
! cry form.
The prismatic or foliated mica is also
used by passing it through mill. This
vastly increases the mica's bulk and
forms masses of bran-like scales, trans
lucent and beautiful. The French sill
yer holdings are also made with this
ground mica. The unalterable nature
of mica and the fact that it entirely re-
sists the action of corrosive acids, smoke
and dust, make it valuable ma
terial for edifcial decoration.
1t can be readily colored or metal
ll2ed. and Its transparency preserves in
all its pristine beauty anything to which
it is applied. This ground mica is also
used as a lubricant and axle grease, and
for such purposes has no superior ex.
cept plumbago. Coarsely pulverized il
is also used for roofing material and as q
tireprooting for iron safes.
The cleavage of mica is so perfect il is
estimated that it can be split or divided
into leaves 250,0 to an inch. The
cious structure are obtained from the
Siberian mines, and they sometimes
attain diameter of and 7 feet
Crystals over 2 feet in diameter have
been found in Pennsylvania, IS to 2
inches in New Mexico and IA inches il
North Carolina. Blocks of crystal.
weighing over 100 pounds are frequently
mined. The North Carolina mines arc
supposed to be very ancient.
Mica plates found in them when frs
discovered were trimmed to particula
shapes, and it is supposed they wer,
used for windows, mirrors and orna
ments. The number of the mines anC
the magnitude of these ancient opera
tions excite wonder. Some of the mine
are tunnelled to considerable length
and distinctly show marks of chisel
shaped tools. Mica in some form exist
all over the earth, but not in quautitie
of any commercial value. 1t can b
found in granite and quartz rubellite
green tourmaline, feldspar, lepidolit
and other minerals, also in granula
limestone, gneiss and slate. 1t varies i
color from white through green, vel
lowish and brownish shades to black
Its chemical composition is silicite G
alumina and potash with small amour
of iron, magnesia and Soda and about
per cent water.