Mixtures of Electrolytes having a common Ion. 515 



column 4 the observed values obtained by graphical interpo- 

 lation from the observations given above ; and column 5 the 

 excesses of the calculated over the observed values expressed 

 as percentages : — ■ 



Constituent Solutions 







(gramme-molecules per 

 litre). 



Conductivity X 10 8 . 



Difference 

 per cent. 



KOI. | NaCl. 



i 



Calculated. 



Measured. 



3-75 5-12 



2312 



2469 



-64 



3-50 



5> 



2276 



2420 



-6 



300 



n 



2202 



2313 



-4-8 



250 





2109 



2190 



-3-7 



200 



>> 



2013 



2049 



-1-7 



3-88 



5-00 



2323 



2481 



-6-4 





450 



2295 



2429 



-5-5 





400 



2292 



2377 



-36 





3-50 



2261 



2324 



-2-7 





300 



2227 



2260 



-1-4 





250 



2174 



2189 



-0-7 



>> 



200 



2096 



2116 



-1*0 



The differences of the above table agree very well with 

 those found by Prof. MacGregor* in the case of the mixtures 

 examined by Bender, being of the same sign and, in general, 

 for mixtures of about the same mean concentration, of ap- 

 proximately the same magnitude. The results seem, therefore, 

 to be worthy of confidence, and they show clearly that the 

 differences between the calculated and the observed values 

 increase rapidly as the constituent solutions become more and 

 more nearly saturated, reaching in the case of practically 

 saturated solutions 6*4 per cent. 



(B) Sodium Chloride and Hydrochloric Acid. 



The following table gives the results in the case of mixtures 

 of solutions of sodium chloride and hydrochloric acid : — 



* Supra, p. 28-5. 



2N2 



