24 BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



which would in part account for its less pronounced taste. The 

 taste of magnesium ions is probably bitter as appears from the 

 taste of magnesium sulfate solutions. It takds about ^ to ,*■- 

 solutions of this salt to produce a distinctly recognizable bit- 

 ter taste. In the latter concentration the salt is dissociated 

 only about 40 per cent, so that it is an open question as to 

 whether the undissociated molecules of MgS0 4 or the Mg 

 ions cause the bitter taste. Magnesium ions very likely have a 

 bitter taste as other solutions in which they occur have this taste; 

 probably the undissociated molecules also have a similar effect. 

 In solutions of MgCl 2 we have both the bitter taste of the Mg 

 ions and the salty effect of the CI ions. The combined effect 

 is such as to make the taste of the solutions of this salt most 

 disagreeable. A solution of MgCl 2 that was £ was recognized 

 as salty but not as bitter, while ^ and -fa solutions produced 

 both the salty and bitter effects, which is what we should expect 

 according to the dissociation theory and the results obtained in 

 case of MgS0 4 and NaCl as given above. Id ■& solution the 

 degree of dissociation of MgCl 2 is about 70 per cent. The 

 mobility of the ion f Mg is about the same as that of the 

 lithium ion. 



The taste of Ca(N0 3 ) 2 is a trifle sharp in ^ solutions 

 and distinctly bitter in-£. It is a different bitter from that 

 of the solutions of magnesium salts. The bitter taste of the 

 Ca (M) 3 ) 2 solutions is probably due to the Ca ions. The mo- 

 bility of the Ca ions is about the same as that of the Mg ions. 



Solutions of ammonium sulfate give scarcely any salty taste; 

 their taste is rather to be described as bitter. This taste is caused 

 by the NH 4 ions and the undissociated molecules (NH 4 ) 2 S0 4 . 

 The probability is that NH 4 ions have a bitter effect, since 

 K"H 4 K"0 3 solutions, besides creating a sharp, burning taste on 

 the tip and edges of the tongue, also have a bitter taste. 



To get substances whose solutions have a characteristic "me- 

 tallic" taste, silver nitrate and mercuric chloride were selected. 

 It was found that even in ^ solution silver nitrate could still 

 be tasted, while in ^ its taste was very pronounced. From 



