107 / 308
REMOVAL
OF
GRAIN
OIL
BY
FILTRATION.
115
through
a
funnel,
and
so
arranged
that
the
spirit
in
its
fall,
will
not
displace
any
of
the
bone
black
from
any
of
the
shelves.
These
digesting
apparatuses
must
of
course
be
placed
above
the
stands
or
filters,
and
so
arranged
that the
liquid
can
be
conducted
to
the
stands
for
filtration.
The
advantages
of
barrels
over
boxes
are
innu-
merable.
The
pecuniary
advantage
is
an
important
one, as
old
barrels
can
be
made
available
at
an
insig-
nificant
cost
compared
^to
the
boxes.
The
rotary
motion
of
the barrel
brings
the
particles
composing
both
bodies
in
contact,
a matter
not
attainable
in
the
boxes.
It
will
be
seen
that
this
rotary
motion
is
highly
beneficial,
as
the
grain
oil
is
diffused
through-
out
the
entire
mass
of
the
spirit.
The
multiplicity
of
barrels
required
is
the
only
objection
to
them.
To
make
a
spirit
that
will
show
no
traces
of
grain
oil
with
the
nitrate
of
silver
(see
preparation
of
the
test),
requires
the
spirit
to
be
digested
with
and
filtered
through
bone
black
;
the
digestion
should
continue
from
four
days
to
a
week,
and
the
peculiar
taste
the
spirit
acquires
from
the
bone
black
not
having
been
sufficiently
burned
to
have
disengaged
the
animal
matter
that
it
contains,
can
be
removed
by
a
subsequent
filtration
through
charcoal
;
after
a
few
barrels
of
alcohol
have
been
passed
through,
the
disagreeable
taste
and
odor
disappear,
that
is,
in
the