Summary. 34P 



at low temperatures is a highly associated liquid containing only a small 

 proportion of H,0 molecules, and that this proportion increases rapidly 

 with rising temperature. Therefore, even though the fraction of H 2 

 molecules dissociated into H + and OH - ions may decrease steadilv, vet 

 the actual concentration of these ions continues to increase until a large 

 proportion of the complex water molecules have been depolymerized. 

 This explanation was suggested by Dr. H. T. Kalmus of this laboratory. 



Among the other results of these investigations, it deserves to be 

 mentioned that, incidentally to the conductivity determinations, the specific 

 volume of several solutions at 218, 281, and 306 was measured. That 

 of the 0.002 normal solutions which can be regarded as identical with that 

 of pure water, was found to be 1.187 at 218, 1.337 at 281, and 1.437 at 

 306. By interpolating graphically from these results the value 1.305 is 

 obtained for 270. Ramsay and Young* found 1.188 at 218 and 1.300 at 

 270, the highest temperature to which their measurements extended. 



In addition to the conductivity researches at high temperatures, an 

 investigation made by A. A. Noyes and Y. Kato of the ion-transference 

 attending the electrolysis of solutions of hydrochloric and nitric acids at 

 20 has been described in this publication (in Part XI). The investiga- 

 tion was along the same lines as the one previously described by Noyes 

 and Sammet.f Its main object was to determine what the value of the 

 equivalent conductance of hydrogen-ion is and whether it varies to an 

 important extent with the concentration. 



The results will be found summarized in the table on page 327. It will 

 be seen that the transference number of the anion in both nitric acid 

 and hydrochloric acid decreases greatly as the concentration increases, 

 and by a corresponding amount for the two acids up to 0.02 normal. 

 This fact strongly indicates that hydrogen-ion, unlike the ions of neutral 

 salts, increases in equivalent conductance or specific migration-velocity 

 with increasing concentration, the magnitude of the increase being nearly 

 five per cent between zero concentration and 0.02 normal. In deriving 

 from conductivity data ionization values for largely ionized acids, it 

 seems, therefore, most appropriate to divide the equivalent conductance 

 at the concentration in question, not as usual by the equivalent con- 

 ductance extrapolated for zero concentration, but by a value obtained 

 by adding to the equivalent conductance of the anion that of the hydrogen- 

 ion as derived from transference experiments at the same concentration. 

 It is of interest to note that when this is done for hydrochloric and 

 nitric acids at 20 their ionization is found to be nearly the same as that 



*Phil. Trans. (A), 183, 109 (1882). 



fj. Am. Chem. Soc, 24, 958; 25, 167 (1902-3) ; Z. phys. Chem., 43, 63 (1903). 



