20 BULLETIN OF THE UNIVERSITY OP WISCONSIN. 



■with the protoplasm of the nerve; the other alternative, that it 

 does not reach the nerve because of too slow diffusion is here 

 excluded. 



Salty Taste. — The taste of common salt is generally given as 

 the type of salty taste. It was found that of the persons tested 

 only three could distinguish a slightly salty taste in -^ solution 

 of sodium chloride, while all recognized -§■ as a trifle salty. It 

 requires then a much stronger solution to produce the salty taste 

 than either the sour or the alkaline. In ~ solution Na CI is dis- 

 sociated to the extent of about 91 per cent, and in ■£ to about 

 88 per cent. As equivalent solutions of sodium acetate are 

 not salty, possessing hardly any taste, it is clear that the salty 

 taste of the common salt solutions is due to the chlorine ions- 

 The fact that borax solutions of equivalent sodium content are- 

 not salty and that many of the individuals tested found difficulty 

 and others could not distinguish between ^ solutions of KC1, 

 LiCl, and !NaCl, argues in favor of this view. The taste of the 

 ions of the alkali metals will be discussed later. 



Sodium bromide solutions of the strength ■§■ were found to 

 be distinctly salty by all ; a few seemed to taste the -fa solution, 

 but very faintly. This salt is dissociated to about the same 

 extent as the corresponding solutions of sodium chloride. The- 

 salty taste of the solutions of Xa Br is due to the Br ion. 

 The sense of taste is apparently able to detect this ion in solu- 

 tions nearly as dilute as the chlorine ion. I found that several 

 persons seemed to detect a qualitative difference between •£ 

 !N"aCl and JsoBt solutions by the sense of taste, others again 

 reported no perceptible difference. Those that did find a dif- 

 ference said that the chloride solution was a little sharper than 

 that of the bromide. 



Sodium iodide solutions could be tasted in •£ solutions and 

 more clearly in £. In neither of these cases was the taste, 

 salty. It takes about a ^- solution to cause the salty taste to 

 appear. The same was observed in case of solutions of potas- 

 sium iodide, only here the taste of ■£ solutions was more marked 

 and rather bitter. The behavior of these solutions will again be 



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