The Morristown gazette. [volume] (Morristown, Tenn.) 1867-1920, 1881-05-25
LEAD-PENCILS.
8 Black lead - Net Head at 'An-HToyv Pen-
.. ellis re Made.

l
Probably there is nothing SO univer-
sally familiar in use, and also so utterly
| unknown to the users in It's nature and
origin as the common lead-pencil, The
| consumption of it in this country alone
being estimated by the most competent
authority at seventy-eight millions pdr
year. Its very name, perpetuating the
old Ieaden plummet familiar among the
treasures Of tie boys first pocket, IS q
missioner and mistake, black lead ="
having no more resemblance to laad
than chalk has to cheese. Most people
suppose the "lead /" is melted and poured
into the hole in the pencil wood but it
IS ground to an almost impalpabla
powder, mixed to a paste with water,
made into a long coil like wire by being
forced through a small hole Gust as
water issues from a syringe), straightened,
and cut in lengths and baked like pot
terry. The hardness is due to an
admixture of clay The pencil is made
in two halves by machinery at a cheap
ard rapid rate, and the processes, which
cannot be related here at length, are
among the most interesting in American
factures. The material called "black
lead is as marvellous as India rubber,
although less protean. 1t is simply
carbon, and is an enigma and a bundle
Of Inconsistencies. Its unlikeness to
lead is suggested = saying that its
weight is less than One-fOUrth that of
lead and that while lead fuses at a low
temperature, graphite is not friable at
any temperature known; ON the contrary,
no substance known surpasses it in re-
sisting heat. Carbon in ordinary anthra-
cite burns: carbon in graphite, refuses to
burn A crucible of graphite, buried to
the top in q mass of burning anthracite
carbon in carbOn-not only refuses to
burn. but melts its metallic contents.
The diamond, as is commonly known, is
nearly pure carbon; but so is graphite.
The latter is the sOftest substance dug
from the earth; the diamond is the hard
est substance known. Subject the dia-
mond to sufficient heat, and it parts with
a mysterious something, 4eaving a bit OF
soft and dissimilar carbon; but it has not
yet-unless we accept recent stories
been found possible to reverse the pro
cess and add to the carbon that myster-
ious something. The purity Of graphite
is extraordinary. 1t is sometimes refined
until less than One-twentieth of one per
cent. of other matter than carbon is left
merely a trace The finest specimen
Of gold ever found, probably, was one
from the Ural Mountains, which was
1896 per cent. fine, thus having 1OI
per cent. of foreign substance, against
{. 90 per cent. in the finest graphite; or. i
stating it in another way, the finest gold
had more than five times, and the aver
age gold produced has twenty to fifty !
times as much imDurity as the finest I
graphite. Assuming that
the diamond is perfectly pure carbon, |
this mere trace of impurity is all that
separates the rare, hard, translucent,
costly diamond from the common. exces-
5ively soft, dull, comparatively valueless
graphite, scarcely one-haf as heavy as
Lhe gem; and yet the two are closely !
alike and almost equal in their resistance |
TO fire How these things are so is vet
among the secrets of natures laboratory. |