514 Mr. D. M c Intosh on the Conductivity of 



The Data for the Calculations, 



The method of calculating the conductivity of the mixtures 

 was that described by Prof. MicGregor in the paper referred 

 to above. It requires as data the change of volume on mixing 

 (if not negligible), the conductivities of sufficiently extended 

 series of the simple solutions of about the same dilution as 

 the solutions mixed, and the molecular conductivities of the 

 simple solutions at infinite dilution. 



Specific gravity determinations showed that the change of 

 volume on mixing was in all cases so small as to produce no 

 practical effect on the calculated value of the conductivity. 



Kohlrausch's tables* of the conductivity of solutions of 

 sodium and potassium chlorides furnished sufficient data for 

 calculating the conductivity of mixtures of these salts ; but I 

 found it necessary to make additional observations on solu- 

 tions of hydrochloric acid. Thev are as follows : — 



Concentration 



Molecular 



Concentration 



Molecular 



(gramme-molecules 



Conductivity 



(gramme- molecules 



Conductivity 



per litre). 



xio 8 . 



per litre). 



XlO 8 . 



1:58 



2550 



2-80 



2065 



1-93 



2403 



2-88 



2052 



211 



2347 



3-15 



1960 



2-18 



2305 



329 



1914 



2-24 



2290 



339 



1890 



246 



2245 



360 



1789 



2-51 



2192 



3-83 



1726 



2-56 



2164 



4-13 



1636 



266 



2141 



4-55 



1534 



2-78 



2090 



4-87 



1456 



The values of the specific molecular conductivity at infinite 

 dilution for potassium chloride, sodium chloride, and hydro- 

 chloric acid respectively, were taken to be 1220xl0 -8 , 

 1030 xll)- 8 , and 3500x 10~ 8 according to Kohlrausch's 

 determination f. 



Results of the Calculations. 



(A) Sodium and Potassium Chlorides. 



The following table contains in columns 1 and 2 the con- 

 centrations of the constituent solutions in the mixtures. 

 Column 3 gives the calculated values of the conductivity ; 



* ' British Association Keports ' (1893), p. 148. 

 t Wiedemann's Anncden, xxvi. p. 204. 



