DOC.
12
83
(A
is
a
constant,
T
the absolute
temperature,
S
=
SA - SB
the difference
between the specific
heats,
which
are
assumed
to
be independent
of
T.
For
reasons
of
analogy
(because
during
isothermal
expansion
of
a
gas E
=
AT
=
2T [1]
lg
(vB/VA)),
AT
is
regarded
as
determined
by
change
of concentration.
The equation
is
applied to experiments
of Richards,
who
for
conversions
[2]
of the kind
Mg
+ ZnSO4.aq
=
Zn
+ MgSO4.aq
(where
the initial
ZnSO4
and
the
MgSO4
formed have
the
same
concentration)
by
the electric
method found
that
71
=
"
kS
'
where
K
is
approximately
the
same
for all conversions
examined.
Omitting
the
term
AT,
the author obtains
from
the
above
equation
§
=
-
S(1
+
lg
T)
=
-
6.7
S.
[3]
Mean
values of observations yielded:
[4]
Reaction
Mg
+
ZnSO4
Mg
+
CuSO4
Mg
+
NiSO4
Mg
+
FeSO4
Zn
+
FeSO4
dE
dt
H-S)
5
5.4
5.9
6.3
7.3
Reaction
Zn
+
NiSO4
Fe
+
CuSO4
Ni
+
CuSO4
Zn
+
CuSO4
Fe
+
NiSO4
dE)
dt
H-S)
8
7.5
7
7.4
7.1
The equation
for
E,
applied
to
fusion
as
well
as
to
conversion of
allotropic
elements and
polymorphic
compounds
(again neglecting
the
term
AT)
further
yields
the
proposition:
The
form
which
is stable
at
the
higher
temperature
(e.g.,
liquid)
has
the
higher
specific heat. This conclusion is
almost
always
confirmed
by
experiment.
Finally, it is concluded
from
the