SPECIFIC GRAVITY OF AQUEOUS SOLUTIONS.—ARCHIBALD. 347 
in the preparation of the solutions, and in the calculations, the 
agreement between observed and calculated values seems to me 
to be exceedingly satisfactory, and to justify the conclusion that 
even in this yery complex case it is possible by aid of the dis- 
sociation theory to predict the specific gravity within the limits 
of experimental error. 
Summary of Conclusions. 
(1.) Expression (1) represents observed values of the sur- 
face tension and specific gravity of the solutions examined 
through a range of concentration extending from 0.05 to about 
0.4 or 0.5 equivalent gramme-molecules per litre. 
(2.) It is possible by aid of the dissociation theory of elec- 
trolysis to predict the surface tension and specific gravity of 
mixtures of Potassium and Sodium Sulphate solutions and the 
specific gravity of mixtures of solutions of Potassium and 
Copper sulphates throughout nearly the same range as above, 
within the limits of the error of observation. 
(3.) It is possible by aid of the above theory to predict the 
specific gravity of mixtures of solutions of Potassium Sulphate 
and Sodium Chloride within the limits of experimental error. 
