DOC.
1
7
We
can
therefore
set
K
=
1
and
thereby
obtain
a
definition for the absolute
values of the
c
's. If
we
take this into
account from
now
on,
we
obtain the
a
following expression
for the
magnitude
of the
potential pertaining to
one
equivalent
(molecule):
(SO*a
P
=
P
-
K-
00 V
where,
of
course,
P
denotes another
constant.
We
could
now
equate
the
00
second
member
of the
right-hand
side of this
equation
to
the difference
DmJ- Avd,
where
Dm
is the molecular heat
of
evaporation (heat
of
evaporation
x
molecular
mass),
J the mechanical
equivalent
of
one
calorie,
A
the
atmospheric
pressure
in absolute units,
and
vd
the molecular
volume
of
the
vapor
-
if
the potential
energy
of
the
vapor
were
zero
and
if
at
the
[13]
boiling
point the
content
in kinetic
energy
would
not
change
during
the
transition
from
the liquid
to
the
gaseous
state.
The
first of these
assumptions
seems
to
me
absolutely
safe.
However,
since
we
have neither
a
basis for the
second
assumption
nor a
possibility
to
estimate the
quantity
in
question,
we
have
no
other choice but
to
use
the
above quantity
itself for the
calculation.
In the first
column
of the
following
table
I
entered the
quantities
[14]
jD'm.v
in thermal units, with
D'm
denoting
the heat
of
evaporation minus
the
external
work
of
evaporation
(in
thermal
units).
In the
second
column
I
entered the quantities
Eca, as
obtained
from
capillarity
experiments;
the
third
column
contains the
quotients of
the
two
values. Isomeric
compounds are
once
again
combined
into
a
single
line.