ABSORPTION AND EMISSION CENTER*. 



15 



It is seen that the shifts are towards the 9m region of the spectrum. For 

 the secondary alcohols Weniger gives the following: 



In the case of primary acids Coblentz and Weniger give the positions of 

 the following minima: 



Weniger considers the 3.0 and 6.9mm bands in the alcohols to be related to the 

 hydroxyl group; the 3.4m band in the alcohol, acids, and esters to be related to 

 methylene (CH 2 ); the 7.3m band in the esters and higher alcohols to be also 

 related to methylene; and the bands 5. 9m and 8.2m in all substances for which 

 there are data to carbon monoxide. 



The 9.6^ band in the primary alcohols shifts by 0.5m to the violet when the 

 linking of the hydroxyl is changed to secondary, and 0.5m further changes 

 when the tertiary alcohol is formed. The change from the primary to the 

 secondary linking of the carboxyl group (CH 2 COOH to CHCOOH) causes 

 the doubling of a band in the 8m region, this being true for acids and esters. 

 The band of the carbonyl group is independent of the way in which this 

 group is linked. 



The authors 1 have shown that the effect of the N0 3 group and of free 

 nitric acid is hypsochromous, causing the uranyl bands to shift towards the 

 violet. The effect of free hydrochloric acid or of zinc, aluminium, or calcium 

 chlorides on the uranyl chloride bands is bathochromous. Recently the 

 authors have found that the N0 3 group is hypsochromous with respect to the 

 neodymium and erbium bands. 



Influence of the Solvent. 



Theoretically it would be expected that the position of the absorption 

 bands would be different for different solvents. Kundt's rule that the bands 

 should be shifted to the red as the refractive index increases does not hold. 

 It is usually believed that the application of Kundt's rule is obscured by the 

 formation of compounds between the dissolved compound and the solvent. 

 The formation of such solvates seems to be quite definitely proved for some 

 inorganic compounds and organic solvents. 2 Kauffman, Hantzsch and Glover, 

 Gorke, Koppe and Staiger, and others, have recently shown that the extinc- 



1 Phys. Rev., 28, 143, 29, 555 (1909); 30, 279 (1910). 



2 Anderson: Phys. Rev., 26, 520 (1908). Jones an. 1 Strong: Phys. Zeit., 10,499 (1909); 

 Amer. Chem. Journ., 43, 37, 97 (1910). 



