1912-13.] Compressibilities of Solutions of Inorganic Salts. 291 
weight of the body, S is the specific gravity of the solution, Q is the density 
of water at the temperature of the solution, and m is the concentration 
expressed in gram equivalents per litre. I have calculated this quantity 
for the salts given in the table just quoted, using Rontgen and Schneider’s 
densities. The result is given in the table below 
O 
Molecular Volume. 
nh 4 
K. 
H. 
Li. 
Na. 
I 
52 
47 
36 
36 
NO s 
48 
40 
32 
30 
30 
Br 
44 
37 
27 
28 
24 
Cl 
38 
30 
20 
19 
18 
so 4 
30 
21 
19 
12 
10 
CO s 
10 
8 
1 
OH 
35 
7 
0 
-2 
-4 
A comparison of the two tables shows that in general the order is the 
same in both, the exception being that the terms H and OH occupy a 
different position in the two cases. With this exception, however, we see 
that, for these substances at least, small molecular volume or large con- 
traction corresponds to small compressibility. It is to be noted that the 
terms H and OH are the terms occurring in the formation of the solvent, 
viz. water. It is also noteworthy that, with the exception of the ammonium 
salt, the combinations involving H and OH have all a relatively large 
conductivity, and it is possible that this high conductivity tends to make 
these combinations more compressible than we would expect from their 
molecular volumes. 
The observations referred to in this paper were made in the Physical 
Laboratory of the University of Edinburgh. The general expenses of the 
research were defrayed by grants from the Carnegie Trust, Sir John 
Jackson’s Tait Memorial Fund, and the Tait Memorial Laboratory Fund. 
{Issued separately July 17, 1913.) 
