508 
IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
dilations of free energy may be made are those containing so- 
lutions of the alkali halides or of the halogen acids. From the 
electromotive forces of such cells it has been found possible 
to calculate the free energy of dilution with a high degree of 
accuracy. 
Using potassium chloride as the electrolyte, Maclnnes and 
Parker 6 , determined the electromotive forces of concentration 
cells both with and without transference. From the data thus 
obtained they calculated the transport numbers and the activity 
ratios of the ions. They found that the concentration ratios 
calculated from the conductivity data are invariably higher than 
the activity ratios determined by the electromotive force method. 
As the dilution increases the value of the activity ratio ap- 
proaches that of the concentration ratio. 
Ferguson 7 has measured the electromotive forces of concen- 
tration cells of hydrochloric acid using electrodes reversible to 
both ions, in cells without transference as well as in cells directly 
connected. He also found that the observed activity ratios are 
less than the concentration ratios calculated from the conductiv- 
ity data. The transport numbers for the ions of hydrogen chlor- 
ide are constant in dilutions greater than thirty liters. He con- 
cludes, therefore, that conductivity measurements do give us 
an accurate method for calculating relative ion concentrations 
in the more dilute aqueous solutions of hydrogen chloride. 
Ferguson and Tolman 8 and later Ellis 9 measured the free 
energy of dilution of hydrogen chloride solutions over a wide 
range of concentrations. 
The object of the present investigation was to determine the 
effect of solvent on the free energy of dilution, the transport 
numbers of the ions and the activity ratios of lithium chloride 
in aqueous and alcoholic solutions. 
THEORETICAL. 
In his treatment of the free energy of chemical substances 
Lewis 10 has introduced the terms activity and fugacity. Activity 
has the dimensions of concentration and is defined as “Such a 
property of a .given substance that, (1) if the activity, a , for a 
substance is the same in any two phases, the substance will not 
6 Jour. Am. Chem. Soc., 37, 1445, 1915. 
7 Jour. Physical Chem., 20, 326, 1916. 
8 Jour. Am. Chem. Soc., 34, 232, 1912. 
9 Proc. Nat. Acad., 83, 1916. 
10 Jour. Am. Chem. Soc., 35, 1, 1913. 
