CHEMISTRY OF FLUORESCING URANYL SALTS. 229 



SODIUM COPPER URANYL ACETATE. 



Na Cu[UO2(C 2 H 3 O2)3 3H 2 O] 3 . 



This was the first salt of this series to be discovered by Rammelsberg. The 

 axial ratio is given by Wyrouboff as a : b : c = 0.5354:1 : 0.9950; = 89 55'. 

 The double refraction is weakly positive, plane of the axes normal to b (010) ; 

 the bisectrix 50 from c axis in the acute angle through the face c (001); 

 2 E = 90 50' ; dispersion weak, r < v. According to Wyrouboff, it only 

 becomes uniaxial at 140, while Schwarz finds, the conversion-point at 93.8. 

 This salt was prepared from cupric hydroxide, acetic acid, uranyl acetate, and 

 sodium acetate in weighed amounts. On slow evaporation, large, clear 

 crystals, though not free from twins, were obtained, some being 1 cm. in dia- 

 meter and 2 mm. thick. These were sealed in glass to prevent efflorescence. 



An attempt was made to produce the cobalt salt of this group, but it was not 

 very successful. The manganese, iron, and nickel were not tried. The last salt 

 was studied rather completely by Johnsen 1 in an investigation of twinning. 



URANYL OXALATE. 

 3H 2 O. 



This salt was described by Peligot and Ebelmen 2 and later by Zimmerman. 3 

 This is an apparently amorphous powder produced by adding oxalic acid to 

 the neutral nitrate, which shows under the microscope small grains with 

 brilliant polarization colors and an extinction angle with the long side of the 

 crystals of 13. A specimen of this was prepared by Cragwall and some 

 material was also purified this way. 



DOUBLE URANYL OXALATE. 



The double salts seem to be formed fairly readily, the potassium salt being 

 described by Ebelmen 4 and the ammonium salt by de la Provostage 5 and by 

 Rammelsberg. 6 Wyrouboff 7 makes a comprehensive review, giving the 

 following : 



K 2 UO 2 (C 2 O 4 )2 3H 2 O monoclinic. 



(NH 4 ) 2 UO 2 (C 2 O 4 )2 2H 2 O rhombic. 



Cs 2 UO 2 (C 2 O 4 ) 2 2H 2 O rhombic isomorphous with above. 



T1 2 U0 2 (C2O 4 ) 2 2H2O rhombic isomorphous with above. 



Na 2 UO 2 (C 2 O 4 ) 2 6H 2 O triclinic. 



(NH 4 ) 4 UO 2 (C 2 O 4 ) 3 monoclinic. 



TLj UO 2 (C 2 O 4 )s monoclinic isomorphous with above. 



K UO 2 (C 2 O 4 ) 4 10H 2 O triclinic. 



None of these salts were tried. 



URANYL TARTRATE. 

 UO 2 C 4 H 4 6 .4H 2 O. 



This salt was prepared by Cragwall by the method of Peligot 8 from uranyl 

 hydroxide U0 2 (OH) 2 from the ignition of uranyl nitrate and tartaric acid. 



1 Johnsen, N. Jahrb. Min. B. B., 23, 259. 1907. 



2 Peligot and Ebelmen, Liebig. Ann. Chem. 43, 282, 287. 1842. 



3 Zimmerman, Liebig. Ann. Chem., 232, 300. 1886. 



4 Ebelmen, Ann. Chim. Phys. (3), 5, 200. 1842. 

 6 de la Provostage, ibid., 49. 



6 Rammelsberg, Handbuch d. Krystall. Chem., 264. 1855. 



7 Wyrouboff, Bull. Soc. Fran. Min., 32, 352. 1909. 



8 Peligot, Liebig Ann. Chem., 56, 231. 1845. 



