Juniata sentinel and Republican. [volume] (Mifflintown, Juniata County, Pa.) 1873-1955, 1876-08-23
About Lead Pencils.

1t will, perhaps, surprise some of our
readers when we state as a positive
fact that lead pencils contain nothing
of lead except in the name. Yet such
is the truth.
Lead pencil is. in fact, as mucha mis-
nomer as it would Ge to call horse a
COW. Red lead as an oxide of lead and
white also a carbonate of that metal,
but the black lead used in pencils Is
neither metal nor compound OF
metal. 1t is plumbago or graphite, one
of the forms of carbon.
Formerly the square pieces of graph
lite which form the marking portion OF
the pencil. Were sawed out of large
masses of hat material, but when PEN
ellis came INTO such universal useIt was
found that this method of procedure
necessitaied so much waste, that 1t was
quickly discovered that some other
process must be used IN order TO utilize
the waStage. In such cases, the want
is stnlom felt before some ready in
Yentor's brain supplies the remedy.
SO it was here. After the experiment
ing necessary to bring any invention
down to practical working basis the
following method was matured:
The fragments of graphite are
ground fine, calcined, and mixed with
pure clay. This clay has been prepared
by diff'using il through water, allowing
the cuarser particles TO settle, drawing
off the milky fluid from the top and
letting it settle again. The latter sedl-
ment is exceedingly fine aud plastic,
and after being dried on linen filters
is fit for use. Ii is then mixed with
powdered graphite in various proper
portions, according to the degree OF
hardness required in pencll-twO
parts of clay 10 one of graphite being
used for fine, hard grade, equal parts
for a soft one, and intermediate
mixtures for the grade between.
The materials after being mixed. are
triturated OF kneaded with water until
they are about the consistency OF
dough. This is pressed into grooves
in an otherwise smooth board, dried IL
the mould by a moderate heat, then
taken out aud baked in covered cruel
bles in a furnace. Sometimes the
dough is compressed in strong
receiver and out through small hole
in a thread of the shape required, ther
dried and baked as above.
The grade of the lead depends alst
partly upon the degree of heat To whlcl
1t is exposed in the furnace. Leads
intended for very fine work, like
architectural drawing, etc, art
reheated after the baking and INNER
sed in melted wax or suet.
The wood used for ali the better
kinds of pencils is the Florida red
cedar. 1t is first thoroughly seasoned
then sawed into strips, dried again land
then cut into strips of proper size fol
pencils. They are grooved by mach
inery, the leads are glued into the
grooves, and the other half of the WOOD
glued on. After being dried under
pressure they are rounded or otherwise
shaped by kind of lathe or cuttInl
machine, then polished by another
operation, and sometimes painted Ol
vanished by a third, which feeds th,
pencils from hopper and turns then
around under the brush. They ar,
next cut the right length by a circula
saw and the ends made smooth by 6
drop knife, after which they are stamp
ped 10y a heated die and sent to til,
packing-rOom to he packed for sale.