124 Studies on Solution. 



PROCEDURE. 



Six U-shaped cells were used in this work. Five of them had con- 

 stants in the neighborhood of 14,000, while the sixth cell had a constant 

 of 29,941. The constants were determined by means of a half-molar 

 solution of potassium chloride. The molecular conductivity of this 

 solution was found to be 115.71 reciprocal ohms at 25 C. 



Two solutions were first made isohydric by the means described 

 above. The specific conductivities of these solutions were measured 



a 



by the usual method and calculated from the formula s = k 7 The 



bw 



same cell was employed for both solutions, so that any change in the 

 cell constant or any error in its determination would be eliminated for 

 comparison. Pairs of solutions were made which were isohydric with 

 regard to each other and of a known molarity for an added salt. Three 

 concentrations of each added salt were used. The specific conduc- 

 tivities of these solutions were now determined. When the conduc- 

 tivity of a solution, say molar with regard to potassium nitrate and 

 hall-molar with regard to sodium nitrate, had been measured, the cell 

 was thoroughly cleaned and dried. The same cell was now used for 

 the determination of the conductivity of a solution 0.6984 molar with 

 respect to calcium nitrate that is, isohydric with potassium nitrate 

 and half-molar in regards to sodium nitrate. Thus possible errors 

 were avoided. 



The increase in conductivity of each isohydric solution was calculated 

 for each added salt at every concentration and results are given in the 

 third and fifth columns of each of the following tables. The difference 

 between the increases for comparable solutions is found in the last 

 column of each table. At the top of each table the concentrations of 

 the two solutions which were isohydric are given. 



In all cases the numbers given for conductivities are in reciprocal 

 ohms and represent the mean of at least three readings on the bridge 

 for different resistances. 



