164 Conductivities and Viscosities in Pure and in Mixed Solvents. 



SALTS. 



The sodium chloride, potassium chloride, and ammonium chloride 

 were the best grade of Baker's analyzed chemicals. These salts were 

 carefully recrystallized from conductivity water and thoroughly dried. 

 The calcium chloride, magnesium chloride, and strontium chloride were 

 from Eimer and Amend. These were dissolved in conductivity water 

 and filtered. They were not recrystallized, being so soluble, but, as 

 later described, were used as concentrated solutions. 



SOLUTIONS. 



Solutions of the non-hydrated salts were made by dissolving the 

 requisite weights of salt in the two isochloric solutions and diluting 

 to the mark with these two solutions. It was found that the volume 

 change caused by the added salts was very considerable in the more 

 concentrated solutions. This means that the solutions, when made, 

 would be of the proper strength for the added salts, but weaker for the 

 isochloric solutions. Part of the space occupied by the isochloric 

 solutions is now taken by the added salt. However, the change in 

 volume in the two isochloric solutions was the same for the same added 

 salt. This would still allow the results to be comparable, even though 

 no correction had been made for the volume change. 



Solutions of the hydrated salts were made by using the quantities 

 of a concentrated solution of known strength necessary for the nor- 

 mality desired. Instead of using isochloric solutions, the necessary 

 amounts of potassium chloride and of a concentrated solution of calcium 

 chloride were employed. The solutions were now brought to the calibra- 

 tion mark by conductivity water. In this way a solution was obtained 

 accurate with respect to the isochloric solution as well as to the added 

 salt. The strengths of the various concentrated solutions were deter- 

 mined by an estimation of the chlorine as silver chloride. The analyses 

 were, of course, made in duplicate. All solutions were made up at 25 C. 

 The same flask was used for normal solutions throughout. This was 

 likewise done for half-normal and eighth-normal solutions. 



PROCEDURE. 



The specific conductivities of the two solutions which were isochloric 

 were first measured and computed from the formula s = K T' The 



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. 



Solutions were made in the manner described, which were isochloric 

 with regard to the potassium chloride and calcium chloride, but which 

 were also of a known normality for an added salt. The specific con- 



