224 FLUORESCENCE OF THE URANYL SALTS. 



The double acetates as a group were studied by Wertheim, 1 Schabus, 2 

 Grailich, 3 Weselsky, 4 and Rammelsberg. 5 The acetate group in general show 

 much less intense fluorescence, tending to be of a dull yellow color. 



The uranyl double acetates with bivalent metals may be divided into two 

 classes the normal and the abnormal. The group HUC^^HsC^sSH^O 

 appears to act as a unit in forming crystals. In the alkali double salts the 

 water of crystallization seems to be lacking, at least in the well-confirmed 

 cases of the sodium and ammonium salts. The case 'of the manganese, cad- 

 mium, and lead double salts seem also to be an exception, but with the other 

 double acetates the ratio of uranium acetate to bivalent acetate seems to be 

 2 to 1. The water of crystallization is variously given from 7, which was 

 found uniformly by Rammelsberg, to 8 by Wertheim and 10 by Grailich. 

 Since the water is likely to run high, due to occluded mother-liquor, and is 

 such a small per cent of the total weight, it is not unreasonable to assume that 

 these really are all hexahydrates. The manganese, when satisfying this 

 valence ratio, and magnesium salts seem also to have 2 molecules of water to 

 each uranyl radical. In the case of the triple salts this requirement is exactly 

 fulfilled, each valence of base having a UC^^HsC^SE^O group attached to it. 



In the case of the manganese, cadmium, and lead salts, this radical does 

 not seem to act, but simply the two acetates are present in a 1 to 1 ratio. The 

 spectra of the manganese salt was like that of the other double acetates; the 

 cadmium was not formed or else gave a spectrum like that of the single ace- 

 tate, and the lead was one of the salts which showed fluorescence lines coinci- 

 dent with spark lines, so that no generalization can be made. 



SODIUM URANYL ACETATE. 



NaUO 2 (C 2 H 3 O2)3. 



This well-known salt described by Grailich 6 crystallizes in the regular system 

 with the least or pentagonal dodecahedral symmetry. It is usually in the 

 form of tetrahedra, yellow, with light green fluorescence. Johnsen 7 gives the 

 specific gravity as 2.562 and the refractive index as 1.5014. Marback 8 and 

 Traube 9 give the optical rotation as 1.48. The best crystals, up to 3 mm. in 

 thickness by 8 mm. diameter, were obtained on long standing of slightly 

 supersaturated solutions. Dr. Nishikawa tried to obtain X-ray diffraction 

 patterns with these crystals, but could obtain nothing. 



POTASSIUM URANYL ACETATE. 

 KUO 2 (C 2 H 3 O 2 )3H 2 O. 



This salt was described by Wertheim 10 as having 1 molecule of water, which 

 was also found by Schabus 11 and Rammelsberg. 12 A recent determination by 



1 Wertheim, Jour, of Prakt. Chem. 29, 207-231. 1843. 



2 Schabus, Best. d. Kystall gest. i. chem. Lab. Erz Prod. Preischr. Wien. 1855. 



3 Grailich, Kryst Opt. Untersuchung. Preisch. Wien, pp. 151-175. 1858. 



4 Weselsky, Jour. f. Prakt. Chem., 75, 55-62. 1858. 



5 Rammelsberg, Sitz. ber. Acad. Wiss. Berl., 857-887, 1884; Wied. Ann., 24, 293-318, 1885. 



6 Grailich, Preisschr. Wien, 151. 1858. 



7 Johnsen, N. Jahrbuch of Min. B. B., 23, 259. 1907. 



8 Marback, Pogg. Ann. d. Phys., 94, 422. 1855. 



9 Traube, Liebisch Grundries der Phys. Kryst., 327. 1896. 



10 Wertheim, J. Prakt. Chem. 29, 223. 1842. 



11 Schabus, Sitz. ber. k. Akad. Wiss Wien, 857. 1884. 



12 Rammelsberg, Wied. Ann., 24, 293. 1885. 



