Evening star., 1869-10-07
PLUMBAGO AND ITS USRs.

Specimens Of graphite plumbago, or black
lead. from various parts Of the country, are
reaching the General Land Once almost daily
the uses OF which have assumed q great i'm.
portance within the past few years. This
mineral IS more or less pure carbon, and il
met with in the oldest geological formations
According to recent investigations il is the
remnant Of the first vegetable organism of our
globe, and is found in beds or imbedded masses
IN gneiss, granite and mica schists. The first
mention Of il, as used for pencils, was m ade
by Swiss naturalist Of the sixteenth century.
Scheele, in 1779, ascertained its chemical ma.
ture. The purest variety occurs In TurkInsk,
IL the Government OF lrkutsk, in Siberia, and
formerly the purest variety was obtained from
the Borowdale mines in Cumberland, England
However, the value of graphite does not so
much depend upon its purity as upon its grain
and texture
For. pencils, only dense, fne-grained speci-
mems can be employed, while for crucibIes
wnicn are extensively used in the man facture
fsteel, the loose mulmous and scaly-I like kind
Is preferred. The former is only rarely me,
with.
Graphite crusibles are. besides, employed in
mmts for melting precious metals, for which
purpose they are considered greatly superior
TO the so-ealled Hessiar crucible. The cruel
bles of Passau in Bavaria have been celebrated
from the time Of Agricola, the father of Metal
lurgy; they are made, however, of In ore iufe-
Iior quality than formerly. The graphite of
Passau Is imbedded in gneiss in proportions
from IS to - per cent
For the manufacture Of crucibIes the mineral
Is reduced to fine powder, mixed thoroughly
Win one third or one half of ITS weight of CLAW
and stamped in forms and moderately heated
until perfectly dry. This industry is largely
carried OF by the Patent Plumbago Crucible
Company in Battersea, nea- LONDON by which
1t Is imported from Ceylon. The consumption
ls so large that the price of the crude product
has more than doubled within a few years.
The largest crucible works in the United
STATES belong to the successors OF the well
known inventor-Mr. Dixon, IN New Jersey
specimens Of which may now be seen or exhi-
oItpn at the American Institute Fair In New
ork, and in the mineral cabinet OF the General
Land Onice.
With regard 10 the uses OF graphite for pen-
Cils. II Is stated by Mr. BrodIe, a French
chemist, that its chemical nature will cease to
have the importance 1t used to have Mr..
Brodie has succeeded IN obtaining, al a trifirng
Gust, chemically pure black lead from the most
impure graphite. By his method the pIumbago
IS obtained in such purity as to be formed into
Light fakes, which are capable Of being blowa
away by the slightest current OF air
Besides the aforementioned uses plumbago
Is employed for portable chemical furnaces.
mufiies, retorts, and Tubes for chemists. Large
blocks Of pure graphite are sold as high as $50
per pound Mixed with soft soap and lard.
OIL, OF even OF itself, when in finely powdered
s:a;e, n forms valuable lubrieating material.
In galvanoplastics, graphite powder is EN-.
ployec TO cover the casts Of plaster OF paris in
order to Obtain metallic deposits Recently the
idea has been started by French Chemist, that
graphite cannot be considered merely as an
aloropic state OF carbon, but il must be re-
gardeo as a new element. PAUL. observed the
formation OF tins element during the prepara-
tion Of certain cyanogen compounds