154 



Conductivities and Viscosities in Pure and in Mixed Solvents. 



for some time, a known weight of pure sodium oxalate was added. The 

 solution was then acidified and heated. A standard solution of per- 

 manganate was used to titrate this in the usual way. The total amount 

 of permanganate less that which is equivalent to the sodium oxalate is 

 the permanganate used for the oxidation of the sodium formate. (See 

 table 85.) 



SODIUM CHROMATE. 



The original solution of this salt was standardized by precipitating 

 the chromium as mercurous chromate, by means of a solution of mer- 

 curous nitrate. On ignition, the mercurous chromate leaves a residue 

 of chromic oxide which can be weighed. (See table 86.) 



SODIUM DICHROMATE. 



The same method of standardization was used in the case of sodium 

 dichromate as was employed with the chromate. (See table 87.) 



POTASSIUM FERRICYANIDE. 



This salt was dried for more than a month over phosphorus pentoxide. 

 The solution was prepared by weighing the required amount of the 

 dry salt, and dissolving in the usual manner. (See table 88.) 



TABLE 86. Sodium chromate. 



TABLE 87. Sodium dichromate. 



