Lab
Library
Journal
Shop
Sign in
to keep
Share image
1
210
The Fairy-Land of Science
·
Arabella B. Buckley
166
But
what
is
it
that
has
changed
these
beds
of
dead
plants
into
hard,
stony
coal?
In
the
first
place
you
must
remember
they
have
been
pressed
down
under
an
enormous
weight
of
rocks
above
them.
We
can
learn
something
about
this
even
from
our
common
lead
pencils.
At
one
time
the
graphite
or
pure
carbon,
of
which
the
blacklead
(as
we
wrongly
call
it)
of
our
pencils
is
made,
was
dug
solid
out
of
the
earth.
but
so
much
has
now
been
used
that
they
are
obliged
to
collect
the
graphite
dust,
and
press
it
under
a
heavy
weight,
and
this
makes
such
solid
pieces
that
they
can
cut
them
into
leads
for
ordinary
cedar
pencils.
Now
the
pressure
which
we
can
exert
by
machinery
is
absolutely
nothing
compared
to
the
weight
of
all
those
hundreds
of
feet
of
solid
rock
which
lie
over
the
coal-beds,
and
which
has
pressed
them
down
for
thousands
and
perhaps
millions
of
years;
and
besides
this,
we
know
that
parts
of
the
inside
of
the
earth
are
very
hot,
and
many
of
the
rocks
in
which
coal
is
found
are
altered
by
heat.
So
we
can
picture
to
ourselves
that
the
coal
was
not
only
squeezed
into
a
solid
mass,
but
often
much
of
the
oil
and
gas
which
were
in
the
leaves
of
the
plants
was
driven
out
by
heat,
and
the
whole
baked,
as
it
were,
into
one
substance.
The
difference
between
coal
which
flames
and
coal
which
burns
only
with
a
red
heat,
is
chiefly
that
one
has
been
baked
and
crushed
more
than
the
other.
Coal
which
flames
has
still
got
in
it
the
tar
and
the
gas
and
the
oils
which
the
plant
stored
up
in
its
leaves,
and
these
when
they
escape
again
give
back
the
sunbeams
in
a
bright
flame.
The
hard
stone
coal,
on
the
contrary,
has
lost
a
great
part
of
these
oils,
and
only
carbon
remains,
which
seizes
hold
of
the
oxygen
of
the
air
and
burns
without
flame.
Coke
is
pure
carbon,
which
we
make
artificially
by
driving
out
the
oils
and
gases
from
coal,
and
the
gas
we
burn
is
part
of
what
is
driven
out.
Marker
Marker
Fine marker
White-out
Fine white-out
Circle
Paint
Unmarker
Hand
Scalpel
Dice
Sieve
Purify
Undo
Redo
Start over
