MIXTURES OF ELECTROLYTES. McINTOSH. 125 



To determine the accuracy of the volumetric analysis, a 

 solution of sodium chloride was prepared, containing a known 

 quantity of the pure fused salt. The results of the analyses 

 were found to be correct to 0.1 per cent. 



Specific Gravity Determinations. 



The object of specific gravity determinations was the finding 

 of p in the above expression for the conductivity. For this 

 purpose it was necessary to find the specific gravity to the third 

 decimal place only. Hence the determinations were made with 

 a Mohr-Westphal balance which read to the fourth decimal 

 place, and might be trusted in the third. 



In all the mixtures examined p was found to be practically 

 equal to unity. 



Preparation of the Mixtures. 



A 50 c. c. pipette which had been carefully washed, and 

 stood on filter-paper for some time, was rinsed out several times 

 with one of the constituents of the intended mixture, whose 

 composition and specific gravity had been determined. The 

 pipette was filled to the mark, and the solution run into a clean 

 and dry bottle. The pipette was then washed, and the other 

 constituent placed in the bottle as before, care being taken to 

 use the pipette in exactly the same manner in both cases. All 

 mixtures were made at 18C. and the same pipette was used for 

 both solutions, in order that the mixture might consist of exactly 

 equal volumes of them. 



The conductivities of solutions were found to increase on 

 standing, which was doubtless due to portions of the glass being 

 dissolved. The conductivities were therefore measured as soon 

 -after the solutions were made up as possible. 



Capacity of the Electrolytic Cell. 



To find the factor which would reduce the observed conduc- 

 tivities to the standard employed by Kohlrausch, viz., the 

 conductivity of mercury at 0C, the following simple solutions 

 of potassium and sodium chloride were analysed, and their con- 

 ductivities measured : 



