MAPPING ABSORPTION SPECTRA OF VARIOUS SALTS. 45 



X 6720 is very similar to the uranyl bands at X 4590 and X 4750. The general 

 appearance of these uranous bands in the red is very much like that of the 

 aqueous uranous bands. 



Uranoits Chloride in Isobutyl Alcohol. 



A, plate 20, represents the absorption spectrum of uranous chloride in 

 isobutyl alcohol. The uranous bands of this absorption spectrum appear 

 quite sharp, especially when they are broad, as is the case in the upper strips 

 of this spectrogram. The first strip shows a double band at about X 4300. 

 These bands practically merge, especially in the other strips, the shorter wave- 

 length band being much more intense. Quite a sharp band appears at X 4950, 

 with a broad region of absorption on the violet side. With a larger amount 

 of salt this absorption is greatly increased, resulting in a very great widening 

 of the band on the violet side, while the red side widens but little. A band 

 appears at X 5480, a weak band at X 6300, a strong band from X 6400 to X 6600, 

 and a strong band at X 6720. The spectrogram shows the total absence of 

 the uranyl bands, and very slight absorption in the region of the ultra-violet. 

 The upper 'strip shows the wide uranous bands very sharply indeed. 



Uranous Chloride in Methyl Ester. 



B, plate 24, represents the absorption spectrum of uranous chloride in 

 methyl ester. From the absorption spectrum it is apparent that the uranyl 

 salt has been largely reduced, since the uranyl bands do not show at all. 

 Uranous bands appear at X 4300 (about 120 Angstrom units in width). There 

 is a region of strong absorption extending from about X 4700 to X 5100, with 

 the strongest absorption in the longer wave-length portion of this region; 

 resulting in a much greater widening of the band towards the violet as the 

 amount of o salt in the beam of light is increased. There is a band at X 5500 

 about 150 Angstrom units wide and the red bands appear. The red bands are 

 both rather wide, the stronger and narrower one being at X 6730. In strip 3 

 the absorption runs from X 6400 to about X 6760. As the absorption increases 

 this red absorption region widens very unsymmetrically towards the region 

 of shorter wave-lengths. This solution, like most other clear uranous solutions, 

 shows very little general absorption in certain regions of the spectrum. Even 

 the general absorption in the ultra-violet is not so very great. When a large 

 amount of the solution is placed in the beam of light, considerable light still 

 passes through, and the edges of the absorption bands appear quite sharp. 



THE ABSORPTION CENTERS OF URANIUM SPECTRA. 



Important results will probably be obtained by a study of uranyl and 

 uranous compounds at low temperatures. It might be possible to obtain 

 aggregates of sufficient size to be seen by the ultra-violet microscope, or to be 

 observed in a manner somewhat similar to that of the scintillation method of 

 observing the a rays on a phosphorescent screen. The uranyl aggregates could 

 be illuminated by flashes of ultra-violet light and by proper sector arrange- 

 ments the aggregates could be viewed in the intervals between the illumina- 

 tion. These aggregates should then appear as centers of the green uranyl 

 phosphorescence. Neodymium compounds in phosphorogens could possibly 

 be treated in the same manner. These salts should also be studied when under 



