Wheeling register. [volume] (Wheeling, W. Va.) 1878-1935, 1879-08-07
How Load Penoils are Made.

The ordinary pencil is filled with a
preparation of graphite, commonly call
Ell black lead or plumbago, both OF which
are misnOmers, as there is no lead or
plumbum in it. Until quite lately 1t
has been considered by chemists as a
carburet of iron, but il is now generally
acknowledged that although it shows
traces of iron, this metal is only me-
chemically mixed with it-there be-
ing no chemical combination between
the two.
Pencils were originally filled with
square sticks cut from blocks OF graphite
found in the famous BortOwdale mine,
in Cumberland, England, which con-
tanned the purest ever found, but on the
exhaustion of that mine the impure ma
terials 10 be found elsewhere were press
ed into service, after proper publication.
The process adopted by the Dixon Co.,
at JERSEY City, who usea graphite found
at Ticonderoga, \. u, is as follows: The
graphite is first ground fine IN water,
treated with sulphuric and nitric acids,
and after washing clean, heated to a
bright red. Then it is mixed with sutfl-
cient water to make il run freely, and
allowed to pass slowly through series
Of tanks arranged in steps, until
the water leaves the last one OF
the series almost clear, having left
the graphite deposited and graded in the
tanks-the deposit in that nearest the
overflow, being the purest, is used Tor
the finest pencils. The graphite after
being taken from the tanks is dried and
then mixed with pipe-clay obtained
nom Rotterdam, Holland, which has
been purified in the same way as the
graphite, only the very finest being
used for pencils, as the coarse can be
utilized in the manufacture of crucibles.
Upon the amount OF clay used depends
the hardness of the pencil-the more
clay the harder the grade-abOut seven
parts OF clay to ten parts of graphite, by
weight, forming medium. The clay
and graphite is thoroughly mixed with
water and ground like paint, but passed
repeatedly through the mills, as many
as 81 times being considered necessary
for the finest grades. When ground
sufficient, the pasty mass is inclosed in a
bag, and the water is squeezed out by a
powerful press, leaving the compound
in the form OF stiff dough, which is
placed into a cylinder OF a forming ma
chine, and by means of a piston, driven
down by powerful screw, is forced out
M the bottom of the cylinder in the
form of 'leads" that, after being heated
i'm a crucible to a red heat, are ready for
insertion i'm the wooden blocks to cut
into pencils.
The blocks are formed by saving the
wood into pieces as long as pencil, six
times as wide, and half the thickness,
which are afterwards run through Il
planning machine that not only smOOths
them but cuts in each block six grooves
half the thickness of the "leads." In
the grooves in one block the leads are
laid. second block, previously coated
with glue, is laid on the first, and pile
of these compound blocks are next cut
apart into six pencils each, by passing
through machine like moulding ma
chine, having two sets of cutters opera
ting on opposite sides OF the blocks,
each of which cuts half way through the
wood. The cutters III these machines
are so accurately arranged, and run so
true, that when the pencils leave the
machine there is no mark TO show the
line OF separation from the block other
than the Joint of the two pieces Of wood
inclosing the lead, and they are said to
be so smooth that sand-papering would
roughen them. The shaping machine
turns out about - per minute, or over
$4,000 per day. The pencils are then
vanished or colOred by another ma
chine at the rate OF l20 per minute, or
1900 per day; and then polished in
another machine at the rate OF lO6 per
minute, or over $4,000 per day; all by
unskilled labor.-Scicntyfc AlaericaR.