The Tiffin tribune. (Tiffin, Ohio) 1868-1887, 1873-02-13
PInmbago..Blact Lead, Graphlte.

The Purposes for which plumOagO is
yal,aDle, The best methods Of applying
it, the properties aud true character OF
the mineral itself, its sources, and the
circumstances that surround il in the
/ commerce Of the world, the various
grades and adulteratiOns, are all
points upon which great numbers,
ever Of those who come in daily con-
Z tact with it or use it, are bY no means
familiar, and many are wholly ignOr-
ant.
The black lead of commerce, and
whist is so called by the trade, in first
hands, Is found only in Europe, prin-
cipIlly in Germany, that which comes
TO this market being wholly from
that country.
The plumbagO of commerce comes
miinly from the island of Ceylon, in
India, but is found in many parts Of
the United States, being mined
SUCCESSFULLY, however, only at TicOn-
deIoga, in the State of New York. 1t
[ is alsO mined to a small extent in the
/ Ottawa region of Canada, though be-
+ live so far without profit.
/ 1t is, therefore, known in trade as
. CeylOn plumbagO. 1t is very refrac-
tory. l have experimental by sub
( jeCting, for two hours, a piece, with
sharp projecting angles, to heat that
would melt steel, and on cooling
! found the shsTpest points perfect; but
I il Will exhaust if left on the top OF
sueha fire. It is found in veins in q
pure state, is removed in Jumps, and a
/ selection of these forms the ''prime
I lump of commerce.
Tie formation most common in the
pure state is that of laminsted crys-
: tails, Elongated at right angles with the
sides Of the vein, il not more than
| from four to six inches wide; but the
I vein wjdens the capitalization often
radiates from numerous centers, aud
| the Wide formation is very beauti-
/ full: the fOliated variety is equally
valuabIeand more brilliant, but rare
in any quantity; the acicular form Of
crystal i not apt to be as pure in the
lump, but is useful for most purposes;
the granIlated variety, the purest of
all, is oflittle use for crucibles, but,
with sIihble manipulation, produces
the fines grades for electrotyping aud
fine leadpencils, and is unequaled for
lubricatiig. Pure plumbagO is free
from grit when pulveriZed and rubbed
between the fingers, and the polish
produced in the same way is instan-
taneous and very bright, being like
dark shade of polished silver. It is
found mixed with iron, Thombspar
and othg forms of lime, the rock and
earth in which the vein is carried.
and MANY other foreign substances in
furious for all the purposes for which
pure plUmbagO is needed: so that
much can is necessary in purchasing
the raw material for a given purpose.
Lime, forinstance, is fatal to plum
bago fol- crucible making. The
plumbagO is mined in the interior OF
the island of Ceylon, and is brought
down to Colombo III bullOck carts.
Il is there selected into grades so much
as NAV be finely broken up is sifted,
and the cOarser part of this is called
tchips," while the finer part IS called
sdust.n The "dustr from prime lump
is, of eouBe, very different in charact'
er from the dust left from the poorer
grades oflump, and all of it, whether
IumD or dist, after being handled and
packed inbarrels in Colombo, becomes
so black and bright, by the poor arti-
cles rubbing against the good, that the
touch of any expert IS required to dis
tinguish between the grades.
The German black lead is not re-
fractory, and Is therefore useless for
any purpose that brings it in contact
with the fire. 1t has no value for the
erucible maker, or for stove polish, and
is of but little use az a lubricatOr. it
has a very low conducting power,
even in its pure state, and the bestquali-
ty that comes to market is far from
pure. None of It comes in its origi-
nal state as mined, but all of it is
washed and fioated, and so the grades
are produced. In fact, it resembles a
weak black clay more nearly than It
does true plumbago in nature as well
as appearance. 1t is used often on
account of its cheapness, when 1t
would be cheaper to use the real plum
bago even at five times the
price.