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THE BLACK-LEAD MINE IN BORROWDALE.
THE mineral substance from which black-lead pencils are
manufactured has successively been known by the several names of
wad, black-cawke, black-lead,
plumbago, and graphite. In the progress of
chemistry and its application to mineralogy, the original term
wad was abandoned, probably in consequence of the same
name being given by the Germans to a substance somewhat
resembling this in appearance, but of a different nature, viz. an
oxide of manganese: the term black-cawke might be subject
to a similar objection, the word cawke being applied by
miners to a sulphate of Barytes: the names of plumbago and
black-lead, although still retained in common use, tend to
convey an erroneous idea of the subject, as lead forms no
part of its composition, which is found to be principally carbon
combined with a small portion of iron: and graphite,
perhaps the least objectionable term, has scarcely yet obtained
currency.
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