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177
The Story of Alchemy and the Beginnings of Chemistry
·
M. M. Pattison Muir
148
Even
if
the
theory
of
atoms
were
abandoned,
the
generalisation
would
remain,
as
an
accurate
and
exact
statement
of
facts
which
hold
good
in
every
chemical
change,
that
a
number
can
be
attached
to
each
element,
and
the
weights
of
the
elements
which
combine
are
in
the
ratios
of
these
numbers,
or
whole
multiples
of
these
numbers.
Since
chemists
realised
the
meaning
of
Dalton's
book,
published
in
1808,
and
entitled,
A
New
System
of
Chemical
Philosophy,
elements
have
been
regarded
as
distinct
and
definite
substances,
which
have
not
been
divided
into
parts
different
from
themselves,
and
unite
with
each
other
in
definite
quantities
by
weight
which
can
be
accurately
expressed
as
whole
multiples
of
certain
fixed
quantities;
and
compounds
have
been
regarded
as
distinct
and
definite
substances
which
are
formed
by
the
union
of,
and
can
be
separated
into,
quantities
of
various
elements
which
are
expressible
by
certain
fixed
numbers
or
whole
multiples
thereof.
These
descriptions
of
elements
and
compounds
are
expressions
of
actual
facts.
They
enable
chemists
to
state
the
compositions
of
all
the
compounds
which
are,
or
can
be,
formed
by
the
union
of
any
elements.
For
example,
let
A,
B,
C,
and
D
represent
four
elements,
and
also
certain
definite
weights
of
these
elements,
then
the
compositions
of
all
the
compounds
which
can
be
formed
by
the
union
of
these
elements
are
expressed
by
the
scheme
A{n}
B{m}
C{p}
D{q},
where
m
n
p
and
q
are
whole
numbers.
These
descriptions
of
elements
and
compounds
also
enable
chemists
to
form
a
clear
picture
to
themselves
of
any
chemical
change.
They
think
of
a
chemical
change
as
being;
(1)
a
union
of
those
weights
of
two,
or
more,
elements
which
are
expressed
by
the
numbers
attached
to
these
elements,
or
by
whole
multiples
of
these
numbers;
or
(2)
a
union
of
such
weights
of
two,
or
more,
compounds
as
can
be
expressed
by
certain
numbers
or
by
whole
multiples
of
these
numbers;
or
(3)
a
reaction
between
elements
and
compounds,
or
between
compounds
and
compounds,
resulting
in
the
redistribution
of
the
elements
concerned,
in
such
a
way
that
the
complete
change
of
composition
can
be
expressed
by
using
the
numbers,
or
whole
multiples
of
the
numbers,
attached
to
the
elements.
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