This
equation represents
a
relationship
between
p
and
V
for
a
process
of
change during
which
no
heat is
being supplied.
This is
approximately the
case
with
caloric motors [heat
engines]. Such
a
change of state is called adiabatic.
Determination of the
specific
heat of
gases.
A
calorimetric determination of
cv analogous
to the method used
for solid
substances would be
running
into
great difficulties.
One therefore prefers
to
determine
cp directly
and
to
derive cv
from
that.
We
set
up
the
following experimental
arrangement:
device for
adjusting
air stream
intensity
heating
vessel
circular pipe [Fig.]
calorimeter
gas
container
The
gas
stream
flowing through
the
pipe
is
kept
constant with the aid
of the
adjusting
screw
and the manometer, such that the air in the
heating
apparatus
takes
on
a
temperature
T
, which also should remain
constant. The calorimeter will then
gradually change
its initial
temperature t0. In addition, it is assumed that the air leaving the
calorimeter has taken
on
the temperature of the calorimeter. t0 shall
be the temperature of the calorimeter's
surroundings.
We
want
to
find the behavior of the temperature of the
calorimeter:
T
-
t
(mc)
dt
=
m
j
•
c
(T
-
t
)
dz
+*•?
•
dz
-
hO
(t
-
t
)
dz
p
a a
a c
+
12.1
(T
-
t
)
+
-fbzxc
+
-
+
hö\(t
-
t
)\
dz
1
p
a
J
v
a
I
P
a
J
a
f
A' Z(mc)
B(Z mc)
dt
=
A
-
B(t
-
t
)
dz
x
a
'
-
i-lg
[a -
B(t
-
ta)]
= z
+
C
For
z
=
0
we
have
t
=
t0
-
*
lg
[A
-
B
(t
0 -
ta)]
=
C
A
-
B
(
10
-
ta)
B
g
A
-
B(t
-
t
)
Z
'
x a
'
Thus the experiment
provides
for observational data and equations for
the determination of
A
and B. From this
A
and
B
can
be derived
very
57