173 / 230
SPECIAL
DISTILLATIONS.
173
it
wouid,
at
least,
be
attenuated
in
many
instances.
The
difficulty
which
is
attached
to
the
distillation
of
lees-wines
is
the
solid
substances
which
they
retain
in
a
state
of
suspension.
These
substances,
which
are
denser
than
the
wine,
pre-
cipitate
themselves
to
the
bottom
of
the
vessels
in
which
they
are
deposited
;
and
if
these
vessels
are
stills
exposed
to
the
direct
action
of
the
fire,
they
cause
them
to
stick
and
adhere
strongly
to
the
bottom,
where
they
burn
and
give
birth
to
all
the
products
of
the
combustion
of
organ-
ical
bodies,
among
which
the
empyreumatic
oil
is
in
large
quantities.
The
influence
of
this
oil
on
spirituou3
liquors
is
too
well
known.
Several
means
have been
imagined
to
pre-
vent
this
accident.
Experience
has
taught,
for
instance,
that
when
lees-wines
has
gained
the
temperature
of
ebul-
lition,
and
when
vapour
is
formed
in
a
continuous
manner
on
the
bottom
of
the
still,
its
rising,
occasioned
by
the
ascensive
agitation,
is
an
obstacle
to
the
precipitation
of
solid
matters,
and
of
course
to
their
torrefaction.
.
This
phenomenon
is
easily
conceived,
and
it
is
pre-
sumed
it
is
not
in
want
of
being
further
developed.
In
consequence
of
this
observation,
a
vertical
bar
has
been
established
in
the
centre of
the
still,
and
by
these
means
a
chain
has
been
made
to
sweep
the
bottom
of
it.
However,
it
has
been
ascertained
that
this
precaution
is
not
always
efficacious,
and
that
during
the
distillation
the
workman
might
happen
to
be
neglectful
in
alimenting
the
furnace,
so as
to
maintain
the
still
in
a
complete
movement
of
ebullition
;
the
solid
matter,
not
being
any
longer
suspended,
precipitates
itself
to
the
bottom
of the
15"^