64 



A STUDY OF THE ABSORPTION SPECTRA. 



Bands from 20 to 40 Angstrom units wide occur at X 3235, X 3510, X 3640 and 

 X 3785. These bands are slightly wider at 80, but as for all the other 

 erbium bands this widening is very small. Weak and narrow bands appear 

 )), 4165, 4425, 4458, 4500 (strong), 4535, 4540, 4555, 4580, 4685, 4750 

 (30 Angstrom units wide), 4810, 4840, 4855, 4870 (strong and 20 Angstrom 

 units wide), and 4920. X 4920 lies alongside of a fuzzy band extending 

 from X 4910 to X 4950. 



After these comes a rather wide band which for a shorter length of 

 layer would most likely be broken up into a number of much finer bands. 

 This band extends from X 5190 to X 5250. At X 5217 a narrow, sharp line 

 runs through the fuzzier and wider band. Broad (about 30 Angstrom 

 units wide) and very faint bands are located at X 5630 and X 5760. For 

 greater concentrations these would probably show as finer bands. The 

 band at X 6540 is much more diffuse on the red than on the violet side; 

 this possibly being due to a component that is not separated at this tempera- 

 ture. Other bands are located at XX 5365, 5380, 5425, 5445, 5505, 6410, 

 6440, 6495, and 6690. The general effect of rise in temperature here is to 

 cause the lines to become slightly fuzzier and to show more of a " washed- 

 out" appearance. No shift or rise in temperature was noticed. 



Absorption Spectra of Erbium Nitrate and Other Salts of Erbium. 



It was thought to be of interest to test whether the N0 3 group had any 

 hypsochromous effect on the absorption spectra of aqueous solutions of 

 erbium salts. The following approximate wave-lengths of the bands do not 

 show any such hypsochromous effect as was found for the uranyl bands: 



*Hazy. t Strong. J Wide and weak. Weak. 



The crystals of erbium sulphate have a fine absorption spectra. As 

 the water of crystallization is driven off the bands change very consider- 

 ably and become much more diffuse. The reflection spectrum from fused 

 erbium oxide consists of a large number of fine lines. As shown by Ander- 

 son, these lines become wider as the temperature is raised, until they 

 become emission bands. The emission bands are quite broad. Between 

 100 and 600 some of the fine erbium bands shift about 10 Angstrom 

 units. The difference between the wave-lengths of the emission bands and 

 the absorption bands at high temperatures is hidden by the haziness of the 

 bands if it exists at all. 



