SPECIFIC GRAVITY OF AQUEOUS SOLUTIONS. ARCHIBALD. 34" 



of sign is not to be expected in the differences as was observed 

 in the differences between observed and calculated values for 

 the simple solutions. In any case in which variation of sign 

 might be expected, as in the case of mixtures of the Copper 

 and Potassium Sulphates where the solutions mixed were equi- 

 molecular, alternation of sign in the differences is quite satis- 

 factory. 



The results of the above tables would seem to warrant the 

 conclusion that it is posssible by aid of the dissociation theory 

 of electrolysis, to predict the surface tension and specific gravity 

 of mixtures of moderately dilute solutions of Sodium Sulphate 

 with Potassium Sulphate and Potassium Sulphate with Copper 

 Sulphate within the limits of the error of observation, by means 

 of data obtained by observations on simple solutions of these 

 salts. 



Observations on the Specific Gravity of Solutions containing 

 Potassium Sulphate and Sodium Chloride. 



As it appears from the above results to be possible to predict 

 the specific gravity of a mixture of two solutions of sulphates^ 

 and from Prof. MacGregor's results in the case of mixtures of 

 two chlorides also, I thought it would be interesting to see if a 

 similar prediction was possible in the case of a mixture of a 

 sulphate solution with that of a chloride of a different metal 

 In such a case there will be four electrolytes present in the* 

 solution. Hence the formula for calculating, expression (2) on 

 page 335, will involve four each of the quantities &, I, , n, v, and 

 the calculation is thus extremely difficult. Prof. MacGregor has 

 found it practically impossible to calculate even the conductivity 

 in the case of mixtures of any two solutions taken at hap- 

 hazard. I therefore did not attempt to do so in the case of the 

 specific gravity. The plan adopted was that of my paper on 

 the conductivity of solutions containing Potassium Sulphate 

 and Sodium Chloride,* viz., to prepare simple solutions of the 

 four salts having the same concentration of ions and to mix 



* Loc. tit. 



