WORK OF C M. STINE. 



Six independent lines of evidence, all pointing to the existence of hydrates in 

 aqueous solutions, having been established, it seemed desirable to attempt to deter- 

 mine, if possible, the effect of one salt with hydrating power on the hydrates formed 

 by a second salt in the same solution; also the effect of a salt with very small hydrat- 

 ing power on the hydrates formed by another salt. When both salts possess the 

 power of forming hydrates in single solution, the amounts of water taken up by the 

 salts at the same concentrations may be the same, or may vary within wide limits. 

 We proposed to study binary mixtures in which both conditions are illustrated. 



Since we desired to calculate, as accurately as possible, the approximate composi- 

 tion of the hydrates formed in the mixtures, it was necessary to obtain data for the 

 freezing-points, conductivities, and number of grams of solvent in a liter of solution 

 of the various salts employed. In order that we might have the data for the exact 

 normalities of the solutions which we mixed, it seemed advisable to make the neces- 

 sary measurements in the single solutions, rather than to attempt to interpolate 

 from data previously obtained. 



CONDUCTIVITY CALCULATIONS. 



It is well known that when two or more electrolytes are present in the same solu- 

 tion, the conductivity of this solution is not, in general, equal to the sum of the con- 

 ductivities which these electrolytes show in separate solutions of the same normality 

 as that which these salts may be assumed to have in the mixture; but that the 

 conductivity of the mixture is generally less than this sum. If the solutions are 

 isohydric, 1 that is, if the component solutions possess a common ion in equal con- 

 centration, then the simplest condition exists between the conductivities of the 

 single solutions and that of the mixture. This latter condition exists when 



in which a.\ is the dissociation of one of the electrolytes at the dilution V\, and a 2 is 

 the dissociation of the other electrolyte at the dilution r 2 . Such solutions can be 

 mixed in any proportion without altering their dissociation, and hence the conduc- 

 tivity of the mixture is the mean of the conductivities of the component solutions 

 and can, therefore, be calculated according to the equation 



; _ K\P -j-n^i 

 *- P + P' 



in which ki and k 2 are the conductivities, and P and P' the proportions of the com- 

 ponent solutions. 



Unfortunately, we have to deal with no such simple relations as these in the 

 mixtures with which we worked. In our work the viscosity of the mixtures differ s 



'Arrhenius: Wied. Ann., 30. 51 (1887); Zeit. phys. Chem., 2, 284 (1888). 



