18 BULLETIN OP THE UNIVERSITY OF WISCONSIN. 



get at the end organs of taste. It is well known that hydrogen 

 ions in many cases accelerate chemical action, i. e., they have 

 a so-called catalytic effect. Whether it will be found that they 

 accelerate the action that goes on in the nerves or unite with 

 their protoplasm, can not be stated now; it does seem suggestive, 

 however, that the ion which has the least relative mass and by 

 far the greatest mobility can be tasted in more dilute solutions 

 than other substances and causes that peculiar sharp sensation. 



Alkaline Taste. — Dilute solutions of caustic alkalies have the 

 characteristic alkaline taste. The effect upon the tongue is very 

 different from that produced by hydrogen ions. In aqueous 

 solutions the caustic alkalies are dissociated into hydroxyl ions 

 and the ions of the metal or basic radical; thus in the case of 

 NaOH the ions are Na and OH, in the case of KOH, K and 

 OH, etc. Solutions of the hydroxides of sodium, potassium and 

 lithium of the strengths 553, afo m anc ^ m were prepared, and 

 their taste was investigated as in the investigation of the acids. 

 It was found that ^ NaOH could not be distinguished from dis- 

 tilled water; the ^ solution could be tasted very faintly; — 

 the taste was difficult to describe, some calling it a rather stale 

 taste. The ^ solution was reported as alkaline by all, at the 

 same time some also received a slight sensation of bitter from the 

 same. The solution of KOH and LiOH yielded essentially the 

 same results. The persons tested apparently were not able to dis- 

 tinguish any difference either qualitative or quantitative between 

 solutions of equivalent strength of these three alkalies. The al- 

 kalinity of a jj-5 solution of NaOH is plainly recognized by the 

 sense of taste. In this solution the dissociation of the XaOH is 

 practically complete. As a solution of XaCl of equivalent 

 strength is tasteless, as will appear below, it follows that the alka- 

 line taste of the XaOH solution is to be ascribed to the effect of 

 the OH ions. Hydroxyl ions then have the so-called alkaline 

 taste. In stronger solutions caustic alkalies are known to pro- 

 duce nausea. It is probable that this is due to their large con- 

 tent of OH ions, the caustic alkalies being even in fairly concen- 

 trated solutions in a relatively highly dissociated state. 



