THE PHYSICAL PROPERTIES OF AQUEOUS SOLUTIONS. 115 
* = S l J . ecific C01ld uctivity of solution reckoned in units such that /U 1 = resistance 
m ohms of a centimetre cube of the solution between its opposite sides. 
A. — 1000/c/m, the “ equivalent conductivity.” 
A = equivalent conductivity at “ infinite ” dilution. 
h = u x > 4 = v x , so that A = l x + 1 2 . 
a = true coefficient of ionisation. 
v = radius of an ion. 
d l = r x = radius of ion at infinite dilution. 
V = viscosity in absolute units. 
n ~ ~ Hittorf migration number for anion; n x = l—n 2 . 
Confimug ourselves to the case of binary electrolytes composed of monovalent ions 
we have ’ 
k = 
am 
food 
.q. (U + V) 
( 1 ), 
and at infinite dilution 
X = a (u + v) 
A = l x + L 
( 2 ), 
(3). 
is important to note that a and o are the true “ mobilities” of the ions, beiim 
really proportional to the velocities. The numbers usually tabulated as “ mobilities ” 
me an and as, whose sum makes up X. At infinite dilution the distinction ceases to 
, but 14 18 lm P°rtant to keep it in mind for less dilute solutions 
According to Stokes' theorem (vide former paper), the limiting velocity of a'small 
spheie ot radius r in a medium of viscosity , under an applied force P is proportional 
J'T ssummg that the ions are spherical and that they are water-coated, so 
at the friction is always water on water, we should have, if Stokes’ theorem is 
applicable to ionic movements under the electromotive force, 
r 
= cy v v 
wheie C is a constant for monovalent ions.* 
Assuming the validity of the application, the sines of the ions can be ascertained in 
absolute units, as is done in Professor Poyntmg’s calculation in reference to the 
papei, i ut foi oui present purpose we are concerned with comparative 
Salralue 7c7 m VC<1 r°“,‘ measurenie ” ts bivalent ions render it doubtful whether the 
shape It i ? ' aPP ’ led , t0 them - 11 be th * ions differ notably from a spherical 
Seat lit P 6 thSt ** “ “" d ° H i0 " S ’ Mratedi might retire a 
° M thiS Ca ' CUlali0 " in the W* as published in the ‘Zeitschrift fill- Phys. Cheat.,' 53, 
Q 2 
