The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1899-05-13
ARE MADE OF GRAPHITE.
Lead Does Not Enter at all into the
Competition OF Pencils. W

The first thing to be said about lead
pencils is that they are not lead pencils at
all, Once upon a time sticks of lead were
used for making marks on paper aud
wood, and the name has survived. though
nowadays all the pencils are filled with
graphite, or plumbago. This mineral Is
found in only few places in the world
in Cumberland, England, along the
Iaurentian ranges in the province OF
Quebec, and at Ticonderoga. VT. The
largest mines on this continent are at the
latter place.
The graphite is taken in the lum from
The mines and carried to the reducing
mill, where it is ground or pulveriged In
stamp mills undsr water. The fine parti-
elss of graphite float away with the water
through Ii number OF tanks, collecting at
the bottom of these reservoirs. 1t is
picked In barrels, in the form of dust and
sent to the factory, where tens of thous-
ands of lead pencils are turned out every
day. The pulverized graphite is so fine
tlat it really is n DUST dingy in color,
and smooth and oily to the touch. 1t is
divided into various grades of fineness by
floating 1t on water from one tank to an
other. The coarse dust sinks to the bot
tom of the first tank, the next finer TO the
bottom of the second tank, and SO on
down the line, the finest powder for the
finest pencils settling in the last tank.
In another series of tanks the German
pipe clay, which is mixed with graphite
to secure the different grades of pencils
from very soft to extra hard, is graded in
the same way, by floating. The finest
clay is mixed with the finest graphite,
being ground together between stones,
and tina hardness of the pencil is secured
by increasing the proportion Of clay In
the mixture.
For the medium grades seven parts by
weight of clay are mixed with ten parts
of graphite. After the graphite and clay
are ground together the mixture Is put
in canvas bags, and the water is squeezed
out under an hydraulic press, leaving
mass the consistency of putty, The plas-
ter is PLACED in a forming press. which is
small iron cylinder, in which q solid
plunger or piston works up and ldown. A
steel plate having a hole the size and
shape of the lead" is put under the open
end of the cylinder, and this plunger
pressing down forces the graphite through
the hole, making a continuous Thread or
wire of graphite As long as this thread
Is moist 1t Is pliabls, but 1t becomes brit
Tic WubD ury, 81 10 Is uoAuAoA A"Eluiy. ~
Ia cut into three lead lengths, Strengthened
out, and then hardened in cructble over
a coal fire. The leads, When ,taken from
the crucibles. are ready for the wood,
which is pine for cheap pencils and cedar
for more expensive ones. When the strips
of wood are received at the factory they
are run through a machine which cuts in
each one six grooves, round or square,
and at the same time smooths the face OF
the wood.
The filing Of tae strips is done by girls
The first one takes grooved strip OF
wood in her left hand and bunch of
leads in the right. She spreads the leads
out fan shape, and with one motion she
fills the six grooves with leads Next to
her sits another girl, who takes the filled
strips and quickly and neatly lays on au-
other grooved strip which has just
been coated with hot glue by a third
girl. The filed and glued strips
are piled upon each other and put in a
press, where they are left to dry. The
ends of the strips are evened of under q
sandpaper wheel, and then the strips are
fed into Q machine which cuts out the
individual pencils, shapes them, and
delivers them smooth and ready for the
color and polish in six streams. The
ooloring is done with liquid dyes, after
which the pencils are sent through the
vanishing machine. -School and Home.