Bristol news. [volume] (Bristol, Va. & Tenn.) 1867-189?, 1881-05-10
LEAD PENCILS.
"BLACK LEAD" NOT At AII--HoW PEN
CHS ARE MADE.

"BLACK LEAD" NOT AT AII--IoW PEN
CHS ARE MADE.
Probably there Is nothing 80 universal
" familiar in use, and also so utterly
unknown TO the users in its nature and
origin us the common lcad-pencil the
consumption of it in this country alone
being estimated by the most competent
authority at scvcnty-ciglt millions per
year. Its very name, pcrpetuating the
old lcuden plummct familiar among the
treasures Of the boys first pocket Is Il
miSuomer and mistake, "black lead"
having no more resemblance to lend
than chalk has to cheese. Most people
suppose the "lGad' ismcltcd and poured
into the hole in the pencil wood, but IL
is ground TO an almost impalpabc pow
der, mixed to II paste with water, made
into Il long coil like wire by being forced
through small hole Jual rs water IT,
sues from syringe, stmlghlcued and
cut IN lengths and baked like pottery:
The hardness Is due TO an admiNturo
Of clay. The pencil is made in two
halves by machinery at cheap and
rapid rate, and the processes, which can
not be- related here Mt length, are among
the most interesting In American fucto-
rics. The material called "blacl lead'
Is as marvellous as India rubber, nj
though less pr0tcan, 10 is simply car
bon, and ig an enigma and Il bundle Of
Inconsistencies. Its unlkcliness 10 lead
Is suggested by saying that It's weight Is
less than onc-iourlh ,lat Of lead aud
that while lead lliscs 1T II low tcmprrN-
turc, graphite Is not friablo at any tenn
pemlurc known; on the contrary, no
substance known surprises it In resist
Ing heat. Carbon in ordinary anthra-
cite burns; carbon in graphite, refuse,
to burn. \ cruciblc Of graphite, buried
TO the top IN mass Of burning anlhra-
CitC--CUlbOn IN CnrbOn--nOt only rnilsCS
TO burn, but mclt' lts metallic contents.
The diamond, 0s Is commonly known, IL
nearly pure carbon but so Is graphite.
The latter Is the sOllrst substance dug
from the earth; the diamond Is the hard
est Substance known. Subject the dla-
lnOnd 10 sufficient heat ana II parts with
n mysterious something, leaving u bit Of
soft and dlssmillr carbon, hut II Inns not
yct--linlcss we accept recent stories
i'Nll lVVnN I'NNlUlt w lNN'lrN lHN Ilb-
cess and add to the carbon that mystcri-
oue something. The purity OF graphite
Is extraordinary, II II sometimes refined
until less than Oilc-twcnticlh of one per
cent. Of other matter than carbon IL left
merely II trace. The finest specimens
Of gold ever found, probably, wns one
from Tie TRIAL Mountains, which was
Os.OO per cent. fine, thus having lOl
per cent. Of foreign Substance, against
0,20 per cent. In the finest graphite; or,
stating 1t IN another way, the finest gold
baltimore than five times, and the aver
age gold produced has twenty 10 nifty
times rs much lmpurty IA the finest
'rlcondcroga graphite. Assuming that
the diamond ls perfectly pure carbon,
this mere trace Of lmpurlty ls nll that
separates the rare, hard, translucent,
costly diamond from the common, excess
sivcly soft, dull, comparatively value
less graphite, scarcely one half as heavy
ny the gem; aud yet the two are closely
illkc and almost equal IN their resistance
to fire. How these things are ~ Is yet
among the secrets Of naluro's labomto-
~,