CHEMISTRY OF FLUORESCING URANYL SALTS. 



217 



the evaporation of the solution of the oxide in hydrochloric acid, were suc- 

 cessfully prepared and freed from the sirupy mother-liquor so as to give good 



fluorescence spectra. 



DOUBLE CHLORIDES. 



The alkali double chlorides, as was discovered early in this investigation in 

 the case of the ammonium salt, give resolved spectra at room temperature. 

 This makes the group quite important. The four double salts of ammonium, 

 potassium, rubidium, and caesium were prepared. Attempts were made to 

 prepare the double salts with silver, cadmium, zinc, and calcium, and also 

 hydrazine and hydroxylamine, but resulted in each case in the formation of 

 the crystals of the chloride added, in a sirup or mat of the uranyl chloride. 

 The silver was sealed in a tube with a strong HC1 solution as solvent, but 

 although remaining white did not dissolve and recrystallize. The tetramethyl 

 and tetraethyl ammonium chlorides described by Rimbach were not made. 



The alkali double chlorides in general were grown by evaporation in a des- 

 iccator in presence of an excess of HC1, which is necessary to prevent hydrol- 

 ysis of the uranyl chloride. This forces back the solubility of the alkali salt, 

 so that the solutions usually contain an excess of uranyl chloride. The 

 crystals, if allowed to stand in the open air, readily give off acid, turning the 

 color of any indicator paper on which they are placed and in moist atmosphere 

 deliquesce readily, the sirupy uranyl chloride running away from a skeleton 



of alkali chloride. 



POTASSIUM URANTL CHLORIDE. 



K 2 -UCvCl4-2H 2 O. 



This salt was described by de la Projvpstage 1 as occurring in hexagonal 

 tables on c (001) founded by o (111), w (ill), m (110), /x (110), 6 (010), q (021). 

 The crystals measured by Rammelsberg were mostly prismatic along the a 

 axis. The first type were those used in this work, although crystals tabular 

 on b (010) were fairly frequent. 



System triclinic; axial ratio, a: b: c: = 0.607 : 1 : 560. a = 8041'; = 7742'; 



The properties of the crystals were similar to those of the ammonium salt, 

 although the crystals seemed to grow larger more readily. 



1 de la Provostage, Ann. Chim. Phys. (3), 6, 165. 1842. 



