From my college Chemistry texts:
"Graphite, an allotropic form of <A
HREF="http://www.bartleby.com/65/ca/carbon.html";>carbon</A>, known also as
(archaic terms)
plumbago and black lead. It is dark gray or black, crystalline (often in the
form
of slippery scales), greasy, and soft, with a metallic luster. It is a good
conductor of electricity and does not fuse at very high temperatures or burn
easily. It occurs in nature in grayish-black masses, massive or crystalline,
and
is obtained in various parts of the world—in the United States (massive) in
Nevada, Michigan, and Rhode Island and (crystalline) in Alabama and North
Carolina; in Brazil; in the British Isles and on the Continent; and in Sri
Lanka,
Madagascar, and Siberia. It is also prepared artificially by treating hard coal
in the electric furnace, a process discovered by E. G. Acheson. The uses of
graphite are wide and diverse. The so-called lead of pencils is in reality a
mixture of graphite with clay. Crucibles required to withstand high
temperatures
and also electrodes are commonly made of graphite. It is used also in stove
polish, in some paints, and as a lubricant." and " A mineral of a dark
steel-gray color, and of a scaly texture, composed of carbon, with a small
portion of
iron. This name, black-lead, is improper, as it contains no lead. It is
called plumbago, and technically graphite, as it is used for pencils, dry
lubricants, etc."
The lead oxide compounds are yellow lead monoxide, PbO, chocolate- brown
lead dioxide, PbO2 and red trilead tetraoxide, Pb3O4. The only black lead
compound I know of is lead sulfide, PbS.
Jerry Albin
[Non-text portions of this message have been removed]
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