THE PHYSICAL PROPERTIES OE AQUEOUS SOLUTIONS. 
The viscosities are calculated from the formula 
V = pt (A-B/*»), 
1 13 
where for the first series 
A = 0-00001766, B= 0-2819, 
and for the second series 
A = 0-00001763, B = 0-2811, 
the constants being corrected for the change of the time of flow of water at 18° in 
the manner before indicated. 
(c) Determination of density of dilute solutions of KC1 and NaCl at 0 ° C— It was 
necessary for our purpose to determine accurately the solution volumes of dilute 
solutions of KC1 and NaCl at the freezing-point, A pair of pykilometers of large 
capacity (about 330 cub. centims.) was therefore used for this purpose. The solutions 
were made up by dilution at 18° C. from normal solutions, and ranged from N /2 to 
N/32. 1 he pyknometers were packed in ice in a refrigerator for two or three hours 
in order to secure a correct temperature adjustment. The air corrections for the 
weighing operation were calculated from the temperature and pressure in the 
laboratory from time to time. The observed densities are given to the sixth 
place of decimals, though the sixth place is only of value as fixing the fifth place 
more accurately. 
The “ observed " solution volumes are calculated from the densities by means of 
the formula 
Po 
1000 
mE p lt 
(p-po), 
where p 0 is the density of water at 0 C C., m is the concentration in gram-molecules 
per litre of solution, E is the equivalent weight of the solute. 
In order to obtain expressions for the solution volume in terms of the hydration h, 
a formula of the same form as is shown to hold for ] 8° C. was used ( vide post , 
Part TV. (a)), viz., V s = c — b-y , where y — (1+B h~ 2/3 )~ 3 . 
For densities at 18 ° C. we were able to determine B from the conductivities by the 
method stated in Part III. (g). But no sufficiently accurate series of conductivity 
values at 0° C. was available for determining B in this manner. Hence the value 
of B was determined by taking trial values of B until, on setting out the resulting 
values of V s upon the resulting value of y, the points ranged approximately in 
a straight line. A considerable difference in the value of B makes little difference 
in the values of V„ or in the limiting value which is obtained by putting y = 1. 
The value of B was taken as 6 in the case of KOI, and 4 in the case of NaCl, and 
with these values of B the values of y were calculated. 
fhe values of h (the number of molecules of water per molecule of solute) are not 
VOL. CCVI. —A. o 
