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177
The Story of Alchemy and the Beginnings of Chemistry
·
M. M. Pattison Muir
112
But
in
the
17th
century,
and
throughout
most
of
the
18th,
only
a
few
of
those
who
examined
changes
in
the
properties
of
substances
paid
heed
to
changes
of
weight;
they
had
not
realised
the
importance
of
the
property
of
mass,
as
measured
by
weight.
The
convinced
upholder
of
the
phlogistic
theory
had
two
answers
to
the
argument,
that,
because
the
earth-like
product
of
the
calcination
of
a
metal
weighs
more
than
the
metal
itself,
therefore
the
metal
cannot
have
lost
something
in
the
process;
for,
if
one
portion
of
what
is
taken
away
weighs
more
than
the
metal
from
which
it
has
been
separated,
it
is
evident
that
the
weight
of
the
two
portions
into
which
the
metal
is
said
to
have
been
divided
must
be
considerably
greater
than
the
weight
of
the
undivided
metal.
The
upholders
of
the
theory
sometimes
met
the
argument
by
saying,
"Of
course
the
calx
weighs
more
than
the
metal,
because
phlogiston
tends
to
lighten
a
body
which
contains
it;
and
therefore
the
body
weighs
more
after
it
has
lost
phlogiston
than
it
did
when
the
phlogiston
formed
part
of
it;"
sometimes,
and
more
often,
their
answer
was--"loss
or
gain
of
weight
is
an
accident,
the
essential
thing
is
change
of
qualities."
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