114 MR. W. R. BOUSFIELD: TONIC SIZE IN RELATION TO 
quite the same for solutions of KC1 and NaCl of equal concentration, but this again 
makes no appreciable difference, and the mean values of li were taken for both. The 
empirical formulas thus derived for the solution volumes were 
for KC1.V, = 0-3658-0-059 y, 
for NaCl.V s = 0-3015-0-089 y. 
In the following table are set out the observed densities, the “ observed ” values of 
the solution volumes (calculated from the observed densities), the values of h~ 2 ' s and y. 
the solution volumes calculated from the above formulae and the differences. The 
values of the solution volumes at infinite dilution (obtained from the above formula 
by putting y = 1) are for KC1 CR306S, for NaCl 0-2125. 
Table VII.—Densities and Solution Volumes of KC1 and NaCl at 0° C. 
1 i 
i Concentration. 
L 
/r 2/s . 
7 - 
Densities. 
V s for KC1. 
Vs for NaCl. 
KC1. 
NaCl. 
KC1. 
NaCl. 
Ob¬ 
served. 
Calcu¬ 
lated. 
Dif¬ 
ference. 
Ob¬ 
served. 
Calcu¬ 
lated. 
Dif¬ 
ference. 
N/32 
0-0068 
0-887 
0-923 
1-001479 
1-001305 
0-3133 
0-3135 
_ 9 
0-2194 
0-2194 
+ 
N/16 
0-0108 
0-820 
0-881 
1-003061 
1-002717 
0-3174 
0-3174 
+ 
0-2236 
0-2231 
+ 5 
N/8 
0-0172 
0-745 
0-819 
1-006203 
1-005520 
0-3217 
0-3218 
- 1 
0-2285 
0-2286 
_ l 
N/4 
0 0274 
0 • 633 
0-732 
1-012410 
1-011058 
0-3281 
0-3284 
o 
— O 
0-2356 
0•2363 
N/2 
0-0436 
0-498 
0-617 
1-024633 
1-021920 
0-3364 
0-3364 
+ 
0-2465 
0-2466 
- 1 
Part TII.— -Ionic Size in Relation to Conductivity. 
(a) Theoretical Considerations. —Some confusion still exists in the use of terms 
employed in relation to the theory of conductivity, which makes it desirable to state 
the fundamental equations with precision, and to define the terms used with 
exactness. It will be convenient to set out together the meanings of the symbols 
employed. 
I 1 = absolute velocity of kation (expressed in centimetres per second) under a 
potential gradient of 1 volt per centimetre. 
V = absolute velocitv of anion. 
•/ 
<1 = quantity of electricity liberated by 1 gramme equivalent of any monad 
(<] = 98360 coulombs). 
n = concentration of solute in gramme equivalents per litre. 
h = hydration (number of molecules of water per molecule of solute). 
n = qJJ, v = r/V, mobilities of the ions. 
