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177
The Story of Alchemy and the Beginnings of Chemistry
·
M. M. Pattison Muir
167
The
study
of
radio-activity
has
introduced
into
chemistry
and
physics
a
new
order
of
minute
particles.
Dalton
made
the
atom
a
beacon-light
which
revealed
to
chemists
paths
that
led
them
to
wider
and
more
accurate
knowledge.
Avogadro
illuminated
chemical,
and
also
physical,
ways
by
his
conception
of
the
molecule
as
a
stable,
although
separable,
group
of
atoms
with
particular
properties
different
from
those
of
the
atoms
which
constituted
it.
The
work
of
many
investigators
has
made
the
old
paths
clearer,
and
has
shown
to
chemists
and
physicists
ways
they
had
not
seen
before,
by
forcing
them
to
think
of,
and
to
make
use
of,
a
third
kind
of
material
particles
that
are
endowed
with
the
extraordinary
property
of
radio-activity.
Dalton
often
said:
"Thou
knowest
thou
canst
not
cut
an
atom";
but
the
fact
that
he
applied
the
term
atom
to
the
small
particles
of
compounds
proves
that
he
had
escaped
the
danger
of
logically
defining
the
atom,
the
danger
of
thinking
of
it
as
a
particle
which
never
can
be
cut.
The
molecule
of
Avogadro
has
always
been
a
decomposable
particle.
The
peculiarity
of
the
new
kind
of
particles,
the
particles
of
radio-active
bodies,
is,
not
that
they
can
be
separated
into
unlike
parts
by
the
action
of
external
forces,
but
that
they
are
constantly
separating
of
their
own
accord
into
unlike
parts,
and
that
their
spontaneous
disintegration
is
accompanied
by
the
production
of
energy,
the
quantity
of
which
is
enormous
in
comparison
with
the
minuteness
of
the
material
specks
which
are
the
carriers
of
it.
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