Volt 
of Salt- Solutions. 
123 
with that fraction of the intermolecular space that clearly 
belongs to that molecule. Only, therefore, on the supposition 
that the intermolecular spaces, in different salts in the solid 
state, are coextensive, or nearly so, does the molecular volume 
give any clue to the constitution of the salt ; but I venture to 
submit that the molecular volumes of salt-solutions do more 
than this, and that it is possible, by the comparison of similarly 
constituted solutions, and the effect of heat and concentration 
on their molecular volumes, to determine, not only the mole- 
cular volumes of the salts themselves, but also that of each of 
their constituents, as has, to some extent, been accomplished 
in the case of organic liquids. 
If we compare the molecular volumes (Table I.) of the salts 
of the same acid-radical with different metals, and also those 
of the same metal with different acid-radicals, we obtain the 
following results : — 
A. The Alteration in the Molecular Volume of a Salt-Solution 
resulting from the replacement of Potassium by Sodium. 
(1) In Combination with Chlorine. 
Table II. contains the data necessary for this comparison. 
It is evident from it that, when solutions of the same strength 
are compared, the volume-change as above is 10 to 10*48, or 
(K-Na) 01=10-0 to 10-48 = A. 
Table II. 
No. in 
Table I. 
X. 
KOI. 
NaCl. 
Diff. 
A. 
1- 6. 
2- 7. 
3- 8. 
4- 9. 
5-10. 
50 
4-0 
2-0 
1-0 
0-5 
1949-84 
1917-84 
1857-12 
1827-67 
1813-54 
1897-42 
1876-23 
1836-29 
1817-52 
1808-54 
52-42 
41-61 
20-83 
1015 
5-00 
10-48 
1040 
1041 
10-15 
10-00 
It is to be noted here that A increases with the concen- 
tration. I shall return to this later. 
(2) In Combination with (S0 4 ). 
(K-Na)(^) = 10'39 to 10-44 = A. 
Table III. 
No. in 
Table 1. 
x. 
K 2 S0 4 . 
Na 2 S0 4 . 
Diff. 
A. 
20-22. 
21-23. 
10 
0-5 
1840-10 
1818-77 
1819-31 
1808-32 
20-79 
10-44 
10-39 
10-44 
