10 KANSAS Academy of science. 



struck. It is proposed to continue the boring to a depth of 1600 feet or more. A 

 similar bed of rock salt has been struck at Hutchinson, and from published reports 

 it is about as pure as the Ellsworth sample. 

 Univebsity of Kansas, Oct. 1887. 



SOME EXPERIMENTS ON THE EELATION BETWEEN THE TASTE AND 

 THE ACIDITY OF CERTAIN ACIDS. 



BY E H. S. BAILEY, PH. D. 



Some tests have previously been made on the "Delicacy of the Sense of Taste."* 



The following experiments were suggested in continuation of the same general 

 subject. Normal solutions of the following acids were prepared: Sulphuric, Hydro- 

 chloric, Nitric, Tartaric, Citric, and Acetic. These solutions were diluted so as to 

 make six series; each solution in a series being of one half the strength of the pre- 

 ceding one. The dilution was continued until it was impossible to taste the acid. 

 The stronger numbers of each series were set aside, and the bottles containing the 

 solutions together with some bottles containing water were placed without regard 

 to order upon the table. 



Tests were then made upon these solutions by twenty persons, including some 

 of both sexes. By tasting of these solutions they divided them into two classes, 

 water and acid. The more dilute solutions they usually set aside and tasted a sec- 

 ond time, in order to confirm or disfirm or disaffirm the first impression. 



There was remarkable uniformity in the results. As the solutions were of the 

 same acidimetric strength, it was possible to compare them exactly. In nearly all 

 cases the solution which was ji^ of the normal was the most dilute that could be 

 tasted. This was especially true of the mineral acids. In quite a large number of 

 cases the solution which was ^^ of the strength of the normal was the most dilute 

 organic acid detected. 



There seems to be, therefore, a slightly greater ability to taste the mineral than 

 the organic acids. Whether this is due to some special or characteristic taste of the 

 former, or to its greater persistence, cannot be determined. No attempt was made 

 to name the different acids when thus diluted, and indeed it would require greater 

 delicacy of taste than is usually possessed. 



It was noticed that after standing a short time a variety of molds developed in 

 the dilute organic acid solutions. These were kindly examined for me by Mr. V. L. 

 Kellogg. He noticed especially that there seemed to be some special variety of 

 plant which was the jjrevalent form in each acid, although this did not prevent some 

 specimens of other species from being also present. As the molds developed, the 

 acids lost their strength, as measured by the sense of taste, so that after several 

 weeks no acid could be detected in several of the more dilute solutions. There is no 

 doubt but that the vegetable forms grow at the expense of the organic acids, but 

 how the acids are broken up, and what conditions are necessary, we have not yet de- 

 termined. • 



These tests seem to show that the method adopted in the taste experiments is in 

 general an accurate one. Also in this particular case the acid taste corresponds 

 with the actual amount of acid present as determined by saturation with an alkali. 



*0n the Delicacy of the Sense of Taste, by E. H. S. Bailey and E. L. Nichols: Science, March, 

 1888; also, Nature, March, 1888. 



