The Miller press. [volume] (Miller, S.D.) 190?-current, 1913-02-06
GRAPHITE AND ITS USES.
Mexico Supplies the Finest Brand Of
This Transformed Coal.


In the central part of the Mexi-
can state Of Sonora, twenty miles
from the mining town of La Colo
rada, is one Of the most desolate
spots on earth. A few rude shacks
give sign of human occupancy, and
there are other evidences to show
that mining operations are going
on. Here and there are huge heaps
of some intensely black stuff.
One o discovers, however, that
the black stuff is graphite-not only
that, but it is from this source that
the world gets most of the material
for its best pencils.
The stuff, oddly enough, is obtain
ed from coal beds which in places
have turned into graphite. In fact,
the same beds are actually being
mined in other spots for coal. Ge-
ologists say that the metamorphosis
was brought about by a plutonic
agency-granite 'dikes" pushing
their way up from molten hot strata
down below and changing the coal
into graphite, which today is soft
and friable enough to be dug out
with pickax and shovel.
On being brought to the surface
it is spread out in the hot sun to
dry, and then thrown into piles to
await shipment. Mules not much
larger than st. Bernard dogs haul
it to La Colorado, whence it is for
warded by rail to Michigan for treat
ment.
Water is so carce in the graphite
producing locality that it is doled
out in kerosene cans, ten gallons a
day to each family. There is not
enough of it for reckless washing,
80 that the miners look like negroes.
The famous Siberian graphite is
hard to get out, transportation ia
cilities in that part of the world
being poor, and ever the best Ger
man graphite has to be loated in
water and settled no fewer than
ninety times in order to rid it of its
impurity. But the graphite from
Sonora demands no such elaborate
treatment. Velvety soft and smooth
to the touch, humps Of it are easily
crushed in the hand. After being
ground it is "air fioated"-that is to
say, exposed to a gentle blast of air.
The heavy particles (grit) settle first
and are thus separated out. What
remains are particles almost infinite
ly small, like SCOT.
The graphite thus refined is mix
ed with clay in certain proportions
for making pencils. A good deal of
clay is used for hard pencil leads,
less Of it for soft. The more clay
the harder the pencil. The pencil
with a big lead, extremely soft, such
al carpenters use, has only enough
clay to hold the particles of graphite
together.
The largest use of graphite, how
ever, is for a lubricant. 1t is also
employed extensively in the mixing
Of paints to give ''body." The ia
miliar shiny look of gunpowder is
given by graphite, which furnishes a
coating for the individual grains
and prevents them from sticking
together. Other uses of graphite
are in electrotyping and manufac-
ture of stove polish.
For high temperature crueibles
the only suitable graphite is that
obtained from Ceylon, which has an
unusual structure, being fbrous.
Mixed with clay for a binder, its
fibers in~terlock, and with expansion
and contraction they work in and
ori, so that the crucible does not
break when heated or cooled. Such
crucibles are made from an inch
high to sizes big enough to hold gal
lons.-St. Louis Republic.