72
GENERAL MOLECULAR THEORY OF
HEAT
PVP2"-P
n
If
the
system
considered is
in
"contact" with
a
system
of relatively
infinitely
large
energy
and
of
absolute
temperature
T0,
then
its
distribution
of states
is determined
by
the
equation
E
dv
=
Ce
dpv..ip
n
In this
equation
K
is
a
universal
constant whose
meaning
shall
now
be
examined.
On
the basis
of
the kinetic
theory
of atoms,
one
arrives
at
an
inter-
pretation
of this
constant
in the
following
way,
familiar
from
Boltzmann's
[15]
works
on
the
theory
of
gases.
Let
the
pv's
be
the
orthogonal
coordinates
x1y1z1,x2y2...,xnynzn,
and
E1n1c1,e2n2...,ennncn
the velocities of the individual
atoms (considered to
be
pointlike)
of
the
system. One
can
choose
these
state
variables because
[16]
they
satisfy the condition
E
auv/apv
=
0
(loc.
cit.,
§2).
One
has
then:
nm
= +
2~~'
+ +
1
where
the first
summand
denotes the potential
energy
and
the
second
the
kinetic
energy
of
the
system.
Let
now
an
infinitesimally
small
region
dx1...dzn
be
given.
We
find
the
mean
value of the
quantity
T^l+
*1+
corresponding to
this
region: