226 FLUORESCENCE OF THE URANYL SALTS. 



MAGNESIUM URANTL ACETATES. 

 Mg(UO 2 . (C 2 H 3 O 2 ) 3 ) 2 7H 2 O. 



This salt was found by Wertheim, 1 who assigned it 8 H 2 O, examined by 

 Grailich, 2 who gave 1OH 2 O, and finally given 7H 2 O by Rammelsberg. 3 It 

 was found to crystallize in the rhombic system with the axial ratio 0.8944 : 

 1 : 0.9923, one of the series of five isomorphous salts Mg, Fe, Co, Ni, and Zn. 

 Lang 4 gives negative double refraction, axes in (001) plane, bisectrix a 2E = 

 100, and p < v. This salt was prepared by evaporation of a solution made by 

 adding to a weighed sample of MgO an excess of acetic acid and the cal- 

 culated amount of uranyl acetate. The crystals grow fairly large, up to 5 mm. 

 with some readiness. 



Mg(UO z (C 2 H 3 O 2 ) 3 ) 2 12H 2 O. 



This hydrate, according to Rammelsberg, 5 forms at low temperatures in 

 large, rapidly weathering crystals with an axial ratio of 0.7667:1:0.5082. 

 According to Grailich and Lang, 6 the double refraction is negative, the axes 

 in a (100), bisectric c, 2E=13 for red and 10.5 for blue. The fluorescence 

 is given as very strong emerald green. This hydrate was not obtained for 

 examination. 



CALCIUM URANYL ACETATE. 



The salt was prepared by Weselsky and examined by Grailich. 7 Rammels- 

 berg attempted to repeat this determination and could not obtain good 

 crystals. Grailich found them to be of the rhombic system, with an axial 

 ratio of 0.9798:1:0.3865, with many faces. Lang 8 found interior twins. 

 Grailich found no pleochroism, but greenish-blue fluorescence. This salt was 

 produced according to Weselsky's precipitation method after the addition 

 method had failed. 



STRONTIUM URANYL ACETATE. 

 Sr(UO2(C 2 H 3 O 2 )3)26?H 2 O. 



This salt was also prepared by Weselsky and could not be obtained by 

 Rammelsberg. It was measured by Grailich, who reports it as being in the 

 tetragonal system, with an axial ratio of 1 : 0.3887. No trouble was found 

 in producing it from strontium carbonate, acetic acid, and uranyl acetate. 



BARIUM URANYL ACETATE. 



This salt was first produced by Wertheim and 9 later described by Rammels- 

 berg, 10 both of whom found 6 molecules of water, but neither of whom obtained 

 crystals good enough to measure. The Weselsky method was also necessary 

 to produce this compound, the first attempt giving only the uranyl acetate 

 crystals. 



1 Wertheim, 1. c., 225. 6 Lang, Sitz. her d. Akad. Wiss Wien, 108, no, 562. 1899. 



2 Grailich, 1. c., 152. 'Grailich, I. c., 159. 



3 Rammelsberg, Wied. Ann., 24, 303. 8 Lang, I. c., 107. 



4 Lang, 1. c., 107. 9 Wertheim, I. c., 230. 



6 Rammelsberg, Sitz. ber., 869. 10 Rammelsberg, I. c., 300. 



