URANIUM SALTS. Ill 



glower, with 0.8 ampere (slit 0.08 mm.) , and 3 minutes to the spark. Starting 

 from the comparison spectrum the concentrations are 0.25, 0.185, 0.125, 

 0.083, 0.0625, 0.042, and 0.031 normal, the corresponding depths of cell 

 being 3, 4, 6, 9, 12, 18, and 24 mm. 



This uranyl salt shows a deviation from Beer's law which is different 

 from the deviation of any salt previously studied. All other salts show, for 

 a Beer's law series, a greater absorption at the greater concentration. 

 Uranyl acetate shows the opposite, a greater absorption for the less concen- 

 trated solutions. For the 0.25 normal solution the blue-violet band extends 

 from X 4150 to X 4250. At 0.031 normal it has broadened, so that its limits 

 are XX 4500 and 4050. This broadening of the absorption is gradual. In 

 like manner the ultra-violet band extends to X 4400 for the 0.25 normal 

 solution and to X 4300 for the 0.031 normal solution. 



A 0.188 normal solution of uranyl acetate 14 mm. in length was diluted 

 to 0.007 normal and 380 mm. in length. The absorption was found to be 

 greater for the more dilute solution. The uranyl bands were not shifted 

 and were much broader in the dilute solution. 



Anhydrous Uranyl, Acetate. 



To determine whether the water of crystallization of uranyl acetate, 

 U0 2 (CH 3 COO) 2 .2H 2 0, had any effect on the position of the uranyl acetate 

 bands, the absorption of the anhydrous salt was found in the same way as 

 for uranyl nitrate. Seven bands could be detected, but most of them were 

 quite faint, although stronger than the bands of the nitrate: a, 4905; &, 

 4775; c, 4605; d, 4460; e, 4320; /, 4200; g, 4085. It will be seen that there 

 is a slight shift towards the red as compared with the aqueous solution. 



Uranyl Acetate in Methyl Alcohol. 



For the uranyl acetate the exposure to the Nernst glower, with 0.8 

 ampere and a slit-width of 0.08 mm., was 1 minute. No exposure was 

 made to the spark except for a comparison spectrum. Starting with the 

 strip nearest the spark scale, in Plate 75, B, the concentrations were 0.25, 

 0.20, 0.16, 0.12, 0.10, 0.07, and 0.06 normal. The depth of cell was constant, 

 6 mm. The edges of the blue-violet absorption were as follows: 0.25 nor- 

 mal, XX 4550 and 3850, 0.20 normal, XX 4520 and 3900, 0.16 normal XX 4500 

 and 3950, and 0.12 normal XX 4550 and 4000. The middle of the band would 

 thus come at about X 4270. As the spark was not used the exact edges of 

 the ultra-violet band can not be given. 



The uranyl bands had the following positions: a, 4875; 6, 4720; c, 

 4585; d, 4445; e, 4320; /, 4185; g, 4070; h, 3975. 



A plate was made to test Beer's law. Starting with the strip nearest 

 the comparison scale the concentrations were 0.25, 0.20, 0.16, 0.12, 0.10, 

 0.07, and 0.06 normal, the corresponding depths of cell being 6, 7.5, 9.5, 12, 

 15, 19, and 24 mm. The deviation from Beer's law is the same in direction 

 as for uranyl acetate in aqueous solution and is not nearly so great. For 

 the 0.25 normal solution the limits of the blue-violet band were XX 4470 and 

 3925, the distance between the blue-violet band and the ultra-violet band 



