678
DOC.
639
OCTOBER
1918
for
the
molecular volume calculated
under the
same assumption yields
According
to
Friction
Vol.
Increase
2%
0.56
ca.
0.5
4% 0.6
ca.
0.5
6% 0.55
ca.
0.54
10%
0.5
ca.
0.55
14% 0.5
ca.
0.54
16%
0.56
ca.
0.55
20%
0.62
ca.
0.56
Furthermore,
according
to these
specif.
weights
of
dry
MgSO4
+
7
H2O:
0.59,
and
according
to
the
specif. weight
of
a con-
centrated
(44.44%)
solution
(1.243)
0.56.
Since all these
figures,
which
agree among
themselves to
a
certain
extent
within the
probably
considerable
experimental
error,
have the
same
underlying
assumption
that the
7
H2O’s
in
the
molecular bond
are
retained
and
are
not
added to
the
solvent
water,
as
is
the
case
for Glauber’s
salt,
it
would be
very
interesting
to
compare
with
them the
relevant Glauber’s
salt
figures
on solubility
and
specif,
wt.
of solutions,
which
figures, unfortunately,
are
not available to
me.
MgSO4
anhydrous: spec.
wt.
?-
mol.
wt.
135.-
Drip
time
for
water at
15°-16°:
47.5=
=
n.
2
g
MgSO4
in
98
g
Water:
vol.
of solution
ca.
983/4.
n':
50.4
s.
4 ” 96 "
ca. 971/2
"
54.5
s.
6
94
ca.
961/4
58
10 90
ca. 933/4
67
14 86
ca.
911/4
82.7
16 84
ca.
90 97
20 80
almost
86 114.5
15°-16°.
"
"
"
"
"
"
The
molecular volume
obtains the
numerical factor
(for
K
=
5)
According
to
Friction
Vol.
Increase
[2%]
0.6 0.375
4%
0.75 "
6%
0.71 "
10%
0.77
"
14% 0.96
"
16%
1.17 "
20%
1.2 0.3
Thus,
whereas
the
molecular vol-
ume
has
very exactly
the
same
quan-
tity
for all
concentrations-except
for
20%-when
calculated from
the
increase
in
volume of
the
solvent,
it
is
very
dissimilar when
calculated
from
the friction.-