SURFACE TENSION OF AQUEOUS SOLUTIONS.—BARNES, 65 
From Table VII it seems that the specific gravity of solutions 
of these salts between the concentration of about 0.01 and 0.5 
can be calculated by aid of the formula and with the values of 
k and / given, while for surface tension (Table VIIT) the calcula- 
tion seems possible from a concentration of U.2 to 1.0. 
Mixtures of Solutions. 
For a solution containing two salts, the equation for the 
value of a property, if there is no change of volume on mixing, 
is of the form 
P=P,+ (k,(l—a@,)n, +100.) —— 
1 2 
+(k, (1—a@,)n, +1,%,7,) c 
Unaime 
where the 7’s are the concentrations of the constituent solutions, 
the «s the ionization coefficients of the respective electrolytes 
in the mixture, and the v’s the volumes of the constituent solu- 
tions, the electrolytes being indicated by 1 and 2. 
The ionization coefficients of the salts in the mixture are 
obtained by the before-mentioned graphical method from the 
same curves as were used in the conductivity determinations for 
mixtures of solutions of these salts. The k’s and l’s are the 
ionization constants obtained for the simple solutions, and given 
in Tables VII and VIIL. 
For the specific gravity measurements, equal volumes of the 
constituent solutions were mixed; while Rother mixed equal 
weights of the simple solutions. He, however, gives sufficient 
data for the calculation of the concentration and volume of the 
constituent solutions. 
The following table contains the requisite data for deter- 
mining the values of the two properties from the above equa- 
tion, and also, for the comparison of the results thus calculated 
with the observed values. The volumes of the constituent 
solutions in Table X, are expressed in litres at 18°C. The 
concentrations are expressed as in the former tables. 
‘Proc. & TRANS. N. S. INST. Scrt., VoL. X. TRANS.—E. 
