Section 59. Summary. 149 



and hydroxide ions in it is 11 times as great at 156, and 24 times as great 

 at 218, as it is at 18. 



The disagreement between the two values of the ionization-constant 

 at 218 derived from the hydrolysis data at different concentrations is 

 doubtless due to experimental error in these data, and shows that that 

 error is large. These values of the ionization-constant are therefore to be 

 regarded only as very rough approximations. Far more reliable and accu- 

 rate values have been since obtained by a similar investigation of the much 

 more hydrolyzed ammonium acetate made in this laboratory by Noyes and 

 Kato and by R. B. Sosman and presented in Parts VI and VII of this 

 publication. 



59. SUMMARY. 



In this article have been presented the results of conductivity measure- 

 ments at concentrations varying from 0.0005 to 0.1 normal and at the 

 temperatures 18, 100, 156, and 218 for solutions of hydrochloric acid, 

 sodium chloride, acetic acid, and of sodium acetate alone and in the pres- 

 ence of an excess of acetic acid. The equivalent conductance of these sub- 

 stances at zero concentration was determined by extrapolation or through 

 the law of independent migration-velocity ; and the ionization at the vari- 

 ous concentrations was calculated. The hydrolysis of sodium acetate at 

 156 and 218 was also roughly determined from the decrease in conduct- 

 ance produced by adding acetic acid to its solution ; and from this hydrol- 

 ysis and the ionization-constant of acetic acid, the ionization of water itself 

 was estimated. 



The equivalent conductances at zero concentration of hydrochloric acid 

 and sodium acetate both approach that of potassium or sodium chloride 

 as the temperature rises, thus again exemplifying the principle that 

 the relative velocities of different ions approach equality with rising 

 temperature. 



The ionization (y) both of hydrochloric acid and of sodium acetate, 

 though the former is several per cent larger, and the latter several per cent 

 smaller, under comparable conditions, than that of the neutral salts of 

 the same type previously investigated (see Parts II and IV), yet varies 

 with the concentration (C) according to the same exponential law, 

 (Cy) n /C(l y) = const, where n = 1.38 to 1.47, as does that of the 

 other uni-univalent substances. The ionization of both these substances 

 decreases with rising temperature, slowly between 18 and 100, but 

 more rapidly at the higher temperatures. The ionization of acetic 

 acid also decreases steadily with increasing temperature, its ionization- 

 constants multiplied by 10 6 being 18.2 at 18, 11.1 at 100, 5.4 at 156, and 



