THE PHYSICAL PROPERTIES OF AQUEOUS SOLUTIONS. 
L45 
The deviations from the straight line are within the limits of experimental error. 
These limits are indicated by the duplicate values at the dilute ends, which differ by 
Diagram IX. 
0-01 in the case of KC1 and by (P02 in the case of NaCl. The expressions which give 
the values of the E.M.D. are :— 
For KC1. D = U86 + 0-041 (I.-C), 
„ NaCl.D = 1-86 + 0-037 (I a —1„). 
The values of D calculated from these expressions, together with the differences 
from the observed values, are set out in the last columns of the above tables, the 
maximum difference m the case of KC1 is 0 " 01 , and in the case of NaCl, 0 0 w, and 
these are the same as the duplicate experimental differences. 
It thus appears that the freezing-point depression, both for electrolytes such as 
KC1 and NaCl, and for non-electrolytes such as sugar in dilute solution, may be 
expressed by one formula, viz. :— 
A 
N (1 + a) 
1*86 +CSC, 
since in the case of a non-electrolyte like sugar the ionisation is nil, so that a — 0 , 
and the molecular volume is nearly constant in dilute solution/ so that SI„ — 6 . 
* We are justified in saying that the molecular volume of sugar is nearly constant in dilute solution 
owing to the facts :— 
(a) That the solution volume of sugar in dilute solution is nearly constant. 
(b) That the viscosity of dilute sugar solutions is almost a linear function of the concentration. 
VOL. CCVI.—A. U 
