Part VII. 



CONDUCTIVITY AND IONIZATION OF AMMONIUM HYDROXIDE, 

 AMMONIUM CHLORIDE, AND ACETIC ACID AT 218 AND 306, 

 AND OF SODIUM ACETATE AT 306. HYDROLYSIS OF AMMO- 

 NIUM ACETATE AND IONIZATION OF WATER AT 218 AND 306. 



75. OUTLINE OF THE INVESTIGATION. 



This investigation is substantially an extension to higher temperatures 

 of the investigation of Noyes and Kato (see Part VI) on the hydrolysis 

 of ammonium acetate and the ionization of water at 100 and 156. 

 Noyes and Cooper (see Part V) have, to be sure, determined roughly 

 the ionization of water at 218 from the hydrolysis of sodium acetate; 

 but, on account of the small degree of hydrolysis, the probable error in 

 their calculation is large. It was the object, therefore, of the present 

 investigation to derive as accurately as possible the value of the ioniza- 

 tion of water at 218 and at 306 from the hydrolysis of ammonium 

 acetate. The experimental data necessary are: the conductivities at 218 

 and 306, at small concentrations, of sodium chloride, sodium acetate, 

 hydrochloric acid, sodium hydroxide, and ammonium chloride ; the con- 

 ductivities of ammonium hydroxide and acetic acid at varying concen- 

 trations ; and the conductivity of ammonium acetate alone and with vary- 

 ing additions of ammonium hydroxide or acetic acid. Of these, the 

 data at 218 for the first three substances and for acetic acid have been 

 determined by Noyes and Cooper; those for sodium hydroxide at 218, 

 by Noyes and Kato; those for sodium chloride at 306, by Noyes, 

 Coolidge, and Melcher ; and those for hydrochloric acid at 306, by G. W. 

 Eastman. The data for sodium hydroxide at 306 have not yet been 

 determined, but an estimate of its equivalent conductance for complete 

 ionization has been made on the basis of the results at lower temperatures 

 and the relations to the conductance of the other substances. 



76. APPARATUS AND PROCEDURE. 



The apparatus employed was in principle the same as that used in 

 the previous high-temperature investigations. The conductivity cell or 

 bomb, the details of which have been fully described in Part II, was anew 

 one (No. 4) made in June, 1904.* An open cylindrical platinum-indium 

 electrode was used as in the work of Noyes and Kato. 



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