KAHLENBERQ — ACTION OF SOLUTIONS ON TASTE. 7 



tities of hydrochloric acid and sodium chloride are alike in that 

 they contain chlorine ions in the same concentration, while they 

 differ in that the former contains hydrogen ions and the latter 

 sodium ions. It has always been regarded as axiomatic that the 

 properties of a solution are determined by what the solution con- 

 tains. Hence the differences in the properties of the dilute so- 

 lutions of hydrochloric acid and common salt are simply to be 

 ascribed to the different effects of the H ions and the ]STa ions, 

 the CI ions being common to both solutions. Xow it happens 

 that a solution of hydrochloric acid still has a very pronounced 

 taste at a degree of dilution at which a common salt solution 

 containing a chemically equivalent quantity is perfectly taste- 

 less. It follows, therefore, that the taste of such a dilute solu- 

 tion of hydrochloric acid is simply due to the hydrogen ions it 

 contains. The dilute solution of hydrochloric acid gives one 

 the sensation of sour, and consequently hydrogen ions cause sour 

 taste. The latter statement will be more fullv established be- 

 low. 



From what has been stated concerning the nature of aqueous 

 solutions, it follows that in the case of solutions of non-electro- 

 lytes we have simply to investigate the taste of the dissolved 

 molecules and to seek a relation between the chemical nature of 

 these and the sensations that thev cause; while in the case of 

 solutions of electrolytes, we shall have to consider the taste of 

 both the undissociated molecules and the ions present, trying to 

 discover if possible a connection between the gustatory sensa- 

 tions that these create and the other properties that they pos- 

 sess. It is clear that the study of the second class of solutions 

 may be much simplified by working with dilute solutions. By 

 so doing the taste of individual ions may even be determined as 

 indicated in the preceding paragraph. 



The Seme of Taste. 



The organs of the sense of taste are located in the epithelium 

 of the upper surface of the tongue and possibly also in the lin- 

 ing of other parts of the mouth cavity. The nerves of the 



