120 Conductivity of Aqueous Solutions. Part V. 



quality as was used for preparing the sodium chloride solutions with sul- 

 phuric acid and absorbing the hydrochloric acid gas in pure water, after 

 washing it by passing it through a bottle containing a little water. With 

 the help of a specific gravity determination, two liters of approximately 0.1 

 normal hydrochloric acid were prepared (January 9, 1904) by dilution 

 with pure water. The concentration of this 0.1 normal hydrochloric acid 

 solution was determined by precipitating with silver nitrate and taking 

 the mean of three analyses. One gram of solution was found to give 

 0.014519 gm. AgCl (a. d.* 0.07 per cent). Some of the measurements 

 (with tenth normal HC1) were made with a solution diluted from a hydro- 

 chloric acid solution carefully and independently prepared by Mr. Y. Kato. 

 One gram of this latter solution gave 0.019675 gm. AgCl (a. d., 0.03 per 

 cent). 



For the preparation of pure sodium acetate, about 500 grams of a Kahl- 

 baum sample were crystallized from water, after the salt had been tested 

 with negative results for potassium and the common acids. The salt was 

 partially dried with filter paper. An approximately tenth-normal solution 

 was prepared (March 10, 1904) and analyzed by evaporating it with hy- 

 drochloric acid in a platinum dish, and gently igniting and weighing the 

 residue of sodium chloride. One gram of solution gave on the average, 

 0.005732 gm. NaCl (a. d., 0.09 per cent). A second solution was similarly 

 prepared June 6, 1904, and analyzed three times, twice immediately after 

 its preparation and again on August 1, 1904. One gram of solution gave 

 (1) 0.005588 gm. (2) 0.005592 gm. (3) 0.005601 gm. NaCl or as the aver- 

 age 0.005594 gm. (a. d., 0.08 per cent). 



For acetic acid some Kahlbaum "Eisessig" was subjected three times 

 to fractional freezing in a specially devised apparatus, care being taken to 

 exclude moisture. The liquid obtained was then rectified by distillation, 

 about one-tenth being rejected. From the purified substance an approxi- 

 mately tenth-normal acetic acid was prepared (on May 12, 1904). Quali- 

 tative tests for sulphate and chloride gave negative results. The solution 

 was then standardized against a barium hydroxide solution whose strength 

 was determined by titration against two solutions of hydrochloric acid 

 which had been independently standardized by precipitating with silver 

 nitrate and weighing the silver chloride. One gram of solution was found 

 to contain 0.006105 gm. acetic acid (C 2 H 4 2 ) by titration with one of the 

 solutions and 0.006097 gm. by titration with the other, or, as a mean, 

 0.006101 gm. acetic acid. 



The more dilute solutions of hydrochloric acid, sodium acetate and ace- 

 tic acid were prepared by weighing out a definite amount of the stock solu- 



*a. d. signifies the average deviation of the separate values from the mean. 



