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177
The Story of Alchemy and the Beginnings of Chemistry
·
M. M. Pattison Muir
120
What
happens
when
a
substance
is
burnt
in
the
air?
The
alchemists
answered
this
question
by
asserting
that
the
substance
is
separated
or
analysed
into
things
simpler
than
itself.
Boyle
said:
the
process
is
not
necessarily
a
simplification;
it
may
be,
and
certainly
sometimes
is,
the
formation
of
something
more
complicated
than
the
original
substance,
and
when
this
happens,
the
process
often
consists
in
the
fixation
of
"the
matter
of
fire"
by
the
burning
substance.
Rey
said:
calcination,
of
a
metal
at
anyrate,
probably
consists
in
the
fixation
of
particles
of
air
by
the
substance
which
is
calcined.
Mayow
answered
the
question
by
asserting,
on
the
ground
of
the
results
of
his
experiments,
that
the
substance
which
is
being
calcined
lays
hold
of
a
particular
constituent
of
the
air,
not
the
air
as
a
whole.
Now,
it
is
evident
that
if
Mayow's
answer
was
a
true
description
of
the
process
of
calcination,
or
combustion,
it
should
be
possible
to
separate
the
calcined
substance
into
two
different
things,
one
of
which
would
be
the
thing
which
was
calcined,
and
the
other
would
be
that
constituent
of
the
air
which
had
united
with
the
burning,
or
calcining,
substance.
It
seems
clear
to
us
that
the
one
method
of
proving
the
accuracy
of
Mayow's
supposition
must
be,
to
weigh
a
definite,
combustible,
substance--say,
a
metal;
to
calcine
this
in
a
measured
quantity
of
air;
to
weigh
the
product,
and
to
measure
the
quantity
of
air
which
remains;
to
separate
the
product
of
calcination
into
the
original
metal,
and
a
kind
of
air
or
gas;
to
prove
that
the
metal
thus
obtained
is
the
same,
and
has
the
same
weight,
as
the
metal
which
was
calcined;
and
to
prove
that
the
air
or
gas
obtained
from
the
calcined
metal
is
the
same,
both
in
quality
and
quantity,
as
the
air
which
disappeared
in
the
process
of
calcination.
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