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177
The Story of Alchemy and the Beginnings of Chemistry
·
M. M. Pattison Muir
13
Lucretius
pictured
the
atoms
of
things
as
like
the
things
perceived
by
the
senses;
he
said
that
atoms
of
different
kinds
have
different
shapes,
but
the
number
of
shapes
is
finite,
because
there
is
a
limit
to
the
number
of
different
things
we
see,
smell,
taste,
and
handle;
he
implies,
although
I
do
not
think
he
definitely
asserts,
that
all
atoms
of
one
kind
are
identical
in
every
respect.
We
now
know
that
many
compounds
exist
which
are
formed
by
the
union
of
the
same
quantities
by
weight
of
the
same
elements,
and,
nevertheless,
differ
in
properties;
modern
chemistry
explains
this
fact
by
saying
that
the
properties
of
a
substance
depend,
not
only
on
the
kind
of
atoms
which
compose
the
minute
particles
of
a
compound,
and
the
number
of
atoms
of
each
kind,
but
also
on
the
mode
of
arrangement
of
the
atoms.[3]
The
same
doctrine
was
taught
by
Lucretius,
two
thousand
years
ago.
"It
often
makes
a
great
difference,"
he
said,
"with
what
things,
and
in
what
positions
the
same
first-beginnings
are
held
in
union,
and
what
motions
they
mutually
impart
and
receive."
For
instance,
certain
atoms
may
be
so
arranged
at
one
time
as
to
produce
fire,
and,
at
another
time,
the
arrangement
of
the
same
atoms
may
be
such
that
the
result
is
a
fir-tree.
The
differences
between
the
colours
of
things
are
said
by
Lucretius
to
be
due
to
differences
in
the
arrangements
and
motions
of
atoms.
As
the
colour
of
the
sea
when
wind
lashes
it
into
foam
is
different
from
the
colour
when
the
waters
are
at
rest,
so
do
the
colours
of
things
change
when
the
atoms
whereof
the
things
are
composed
change
from
one
arrangement
to
another,
or
from
sluggish
movements
to
rapid
and
tumultuous
motions.
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