1905 - 6 .] Prof. Gibson on Aqueous Solutions of Electrolytes. 235 
Thus, adopting the recognised symbols : — 
This mode of representation has no doubt one advantage over 
the older mode in which the specific conductivity (k) was referred 
to the percentage composition, for solutions of equal equivalent 
concentrations contain chemically equivalent quantities which is 
obviously not the case in solutions of equal percentage composition ; 
but this advantage is not dependent upon the adoption of the 
unit of volume (litre or cc.), and is equally maintained when the con- 
centration is expressed in gram equivalents per unit mass, that is, 
in gram equivalents per gram or per kilogram. 
The adoption of unit volume instead of unit mass was due 
originally to a certain practical convenience, and proved later on 
very useful in facilitating the correlation of the laws relating to 
dilute solutions with the gas laws. 
By confining investigation to dilute solutions, very great progress 
has been made, but it has seemed throughout as if there were a 
barrier preventing progress in our knowledge of concentrated 
solutions. The barrier lies in the adoption of the unit of volume 
instead of the unit of mass. The specific gravity effect which 
is not negligible in concentrated solution blurs the true relation- 
ship. 
If the following units be taken — 
k — specific conductivity in ohm -1 cm. -1 
y = concentration in gram equivalents per gram 
r = 100u y 
the relation between A M and y approximates very closely over 
considerable ranges of concentration to 
A ^ = a -f by 
where a and b are constants. 
k = specific conductivity in ohm" 1 cm.' 1 
r] = concentration in gram equivalents per cc. 
m= 1000 7] or gram equivalents per litre. 
A = — = equivalent conductivity. 
7 ] 
s = specific gravity. 
(i) 
