KAHLENBERG — ACTION OF SOLUTIONS ON TASTE. 15 



and as astringent and slightly sour by the women, while all 

 found the & and ^ solutions distinctly sour. No difference 

 either qualitative or quantitative could be distinguished by these 

 individuals between the solutions of these various acids of equiv- 

 alent strengths. The electrical conductivity 1 of solutions of 

 these acids shows that in their TO solutions the compounds are 

 practically completely dissociated, the number of undissociated 

 molecules present at this concentration is then practically nil. 

 It will be shown below that the sodium salts of these acids in ^ 

 solutions, or even much greater concentrations, are tasteless. 



In testing solutions of acetic acid it was found that m could be 

 tasted as astringent while ra was reported as sour, though much 

 les6 so than TO solution of the other acids mentioned. The elec- 

 trical conductivity of solutions of acetic acid shows that in ^, 

 and TO solutions the degrees of dissociation are about 6 per cent, 

 and four per cent, respectively. One would then expect acetic 

 acid solutions to be less sour than equivalent solutions of the 

 strong mineral acids; at the same time, it is apparent that if hy- 

 drogen ions can be tasted as astringent in ^ solutions, a ^ solu- 

 tion of acetic acid, which is dissociated only about 6 per cent, 

 and hence with respect to hydrogen ions is ^ normal, ought 

 to be tasteless. To be ^ with respect to its content in hydro- 

 gen ions, a fa acetic acid solution ought to be dissociated 25 

 per cent. It is clear then that the ^ solution of acetic acid, be- 

 ing dissociated only about 6 per cent, has a sour taste about four 

 times as strong as it ought to have, assuming that the taste is- 

 due simply to the hydrogen ions momentarily present. Rich- 

 ards 2 obtained a similar result; he fotmd that the acetic acid was 

 about one-third as strong as an equivalent solution of hydro- 

 chloric acid, though the acetic acid was only dissociated to the 

 extent of one-fourteenth. Eichards gives no explanation of this 

 phenomenon, and at the present time I also have none to offer. 

 The further investigation of this point together with that of the 



J See Ostwald, Allgemeine Chemie 2, p. 722 et seq., also Landolt u. Bornstein's= 

 physikalisch-chemische Tabellen. 

 2 Loc. Cit. 



