The times. [volume] (Richmond, Va.) 1890-1903, 1893-07-26
MICA rs THE STUFF.
In These Days tho World Gould Hardly
Worry Along without 1t.

worry along " ithout 1t.
Mica fills the interstices Of modern pro-
gress A few decades ago we We're seek
ing practical use and market for the ont
put 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 It's relations to all things
Mica Is now as essential 10 the various
uses or electricity as this great force is
! necessary TO human progress. In all an
! planes for electrical lighting and power.
the most important reciprocal agent en-
tering into their mechanism is mica. All
| armatures are built up with this insula-
ton. whether for dynamos. motors. gen
orators, or transformers. Without it's use
as an insulation the core OF the armatlre
would burn out with n flash But bv
placing sheets OF mica between the thin
sheets OF iron, which are secured to the
shaft that runs through the drum Of the
armature, insulation becomes perfect.
Thus armatures OF even the largest gen
orators can be run for twenty-four con-
tinuous hours without heating them more
than so degrees Fahrenheit above the
temperature Of the surrounding air. BY
this use Of mica the lines Of force are
dissipated, but do not lose any of their
electrical energy.
In all electrical safety appliances mica
also performs an important part as an
insulator. To its infusible and indie
structible nature much Of the success Of
the rheostat can be ascribed. This won
dertul mechanism, which IS applied as a |
motor starter, governor Of speed q re- |
FerSlng switch, and an automatic safety |
switch Is absolutely freproof and can |
De subjected 20 a red heat without me
chanical injury. This is rendered pos
sible by making the resistance Of thin
plates OF iron packed closely together.
but separated by mica.
Ihus the lines Of force operate on the
same principle as I'm the armature. Aside
from these important uses Of mica in
electrical apparatus. il is also applied 10
a thousand minor ones, which make Il
the constant and willing servant Of the
greatest power that man has turned 10
intelligent subjugation.
Mica is also an important factor in
many branches Of manufacture and art
Owing TO its pee uliar elasticity and tough
'fss, qualities in which Il is not eXcelled
~ anything Natural or artificial. II IS
'sed as an absorbent Of nltroclycerine
nd wien so used explosions ly percus-
ion are rendered almost impossible.
Vile at the same time nothing Is taken
tom the energy OF the nitroglycerine
Fhen exploded by Eliminates or similar
evice. For such purposes the pumose
lioa is used. or that In which the scales
re arranged in feathery form.
The prismafic or folicatcd mica is also
sed by passing It through a mill This
lstly II creases the mica's bulk. and
rms masses OF bran.like scales. trans
cent and beautiful. The French silver
holdings are also made with this ground
lea. The unslterable nature OF mica and r
he fact ttat It entirely resists the ac. I
on OF cores siye acids, smoke ard dust
axe II valuable material for edifcial
'coration. II can be readily colored or
and its transparency preserves 1
all its pristine beauty anything To
nich IT is applied. This ground mica 6
also used as a lubricant and axle -
ease, and for such purposes has no G
perior except plumbago. Coarsey pui- -
rized 1t Is also used for roofing ma
rial and as hreprooing for iron safes .,
The cleavage OF mica is so perfect IL ie ~
'imated that II can be split or divided L
% leaves 10000 to an inch. Much of =,
commercial value depends upon this
nderful property Of lamination. The IL
gest plates Of mica with such folia- l.,
us structure are obtained from the a.
'erian mines, and they sometimes at I"
n diameter OF five and seven feet. II
ystals over two feet In diameter have u
n found in Pennsylvania, eighteen 10 I"
inches I'm New Mexico. and II
rteen inches in North Carolina. Blocks III
crystals weighing over one hundred g
lnds are frequently mined The North 30
-olina mines are supposed TO be very Az
'ient. -
lea plates found in them when frstf w
covered were trimmed 10 particular lila
pes and 1t Is supposed they were used
windows, mirrors and ornaments. The r
nber OF the mines and the magnitude
these ancient operations excite won w,
Some OF the mines are tunnelled IA
onslderable length. and distinctly show All
KS OF chisel-shaped tools. Mica I'm
10 form exists all over the earth. bur 49,
In quantities OF any commercial val. Mi
IL can be found in granite and III
rtz rubellite. green tourmaline. fields -
lepidolite and other minerals. also
granular limestone. gaeiss and slate.
'aries In color from white through -
H. yellowish and brownlsh shades 10 i
X. Its chemical composition Is silic-
u alumina and potash. with n small ia
unit or iron. ma8nesia and soda. and
II per cent. water.-Chicago Inter
IN. pra