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177
The Story of Alchemy and the Beginnings of Chemistry
·
M. M. Pattison Muir
139
Consider
the
word
water,
and
the
substance
represented
by
this
word.
In
Chapter
IV.,
I
gave
illustrations
of
the
different
meanings
which
have
been
given
to
this
word;
it
is
sometimes
used
to
represent
a
material
substance,
sometimes
a
quality
more
or
less
characteristic
of
that
substance,
and
sometimes
a
process
to
which
that
substance,
and
many
others
like
it,
may
be
subjected.
But
when
the
word
water
is
used
with
a
definite
and
exact
meaning,
it
is
a
succinct
expression
for
a
certain
group,
or
collocation,
of
measurable
properties
which
are
always
found
together,
and
is,
therefore,
thought
of
as
a
distinct
substance.
This
substance
can
be
separated
into
two
other
substances
very
unlike
it,
and
can
be
formed
by
causing
these
to
unite.
One
hundred
parts,
by
weight,
of
pure
water
are
always
formed
by
the
union
of
11.11
parts
of
hydrogen,
and
88.89
parts
of
oxygen,
and
can
be
separated
into
these
quantities
of
those
substances.
When
water
is
formed
by
the
union
of
hydrogen
and
oxygen,
in
the
ratio
of
11.11
parts
by
weight
of
the
former
to
88.89
of
the
latter,
the
properties
of
the
two
substances
which
coalesce
to
form
it
disappear,
except
their
masses.
It
is
customary
to
say
that
water
contains
hydrogen
and
oxygen;
but
this
expression
is
scarcely
an
accurate
description
of
the
facts.
What
we
call
substances
are
known
to
us
only
by
their
properties,
that
is,
the
ways
wherein
they
act
on
our
senses.
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