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KANSAS ACADEMY OF SCIENCE. 



be absorbed while the remaining would be partly reflected and partly transmitted. This 

 is probably the true explanation of selective absorption in gases, and it may be the ex- 

 planation of selective absorption in solids and liquids. One thing that we should expect 

 in the case of solids is, that more than one wave-length would be absorbed, because the 

 molecules would not have a definite rate of vibration, but would vibrate at any rate be- 

 tween certain limits, though with unequal facility. That is, the vibration would be 

 stunted by the attraction of the surrounding molecules. 



It is a well-known fact that gases when heated radiate those wave-lengths which they 

 are capable of absorbing when cold. Now if the above theory of selective absorption 

 and reflection be true, we should expect a colored solid when heated to radiate light 

 nearly complementary to that which it reflects when cold. This seems to be the case 

 with copper, which has a greenish tint when melted, but whether there is such a thing 

 as selective radiation from solids is not certain. The only way to settle this is by a 

 spectrophotometric study of the light emitted by colored bodies in a state of incandescence. 



SOME SPECIAL TESTS IN REGARD TO THE DELICACY OF THE 

 SENSE OF SMELL. 



BY E. H. S. BAILEY AND L. M. POWELL. 

 [Abstract.] 



At the Philadelphia meeting of the American Association for the Advancement of 

 Science, E. H. S. Bailey and E. L. Nichols presented the results of some experiments on 

 the special senses. The object of the present investigation is to continue these experi- 

 ments with special attention to the sense of smell. It is doubtless true that, in the pro- 

 cess of smelling and tasting, actual contact with the substance must take place, and the 

 substance must be soluble, or must be floating in the air in minute particles, 



As we wish to form some idea in regard to the delicacy of this sense, and the effect 

 of education upon it, and to compare it with chemical tests for the determination of 

 substances, we have used as test solutions the following : 



Oil of lemon, 1 part in 4,000 parts of water; oil of wintergreen, 1 part in 2,700 parts 

 of water; Prussic acid, 1 part in 512 parts of water; caustic potash, a dilute solution. 



The oils were obtained in solution in water by grinding with magnesia, and filtering. 

 All the solutions were successively diluted so that each bottle was one-half the strength 

 of the previous one in ttie series, and the dilution was continued till it was impossible to 

 detect the substances by smell. Tests were made by 21 females and 27 males, each one 

 attempting to classify in four groups, as above. Although the number tested is too small 

 to justify an absolute conclusion, yet it is valuable as indicating probable results. The 

 average was as follows : 



AMOUNT DETECTED. 



Three of the males were able to detect one part of Prussic acid in about 2,000,000 

 parts of water. Two of these were persons engaging in occupations favoring the culti- 

 vation of this sense. Careful chemical tests were made for Prussic acid, but it was not 

 detected below the bottle containing 1 part IICN in 131,000 parts of water. More deli- 

 cate tests can probably be made by the use of the microscope. 



