288 P. T. Walden — Double Chlorides and Bromides, etc. 



The Double Bromides. — These are all very dark green, 

 almost black and quite opaque. Like the chlorides, the 2:1 

 caesium salt is darker than the rubidum compound of the 

 same type. As no corresponding potassium or ammonium 

 salt could be made, the comparison can be carried no farther. 

 The caesium and ammonium 1 : 1 bromides are of nearly the 

 same color. ISTone of the double bromides are capable of 

 recrystallization. 



2:1 Caesium and Rubidium Ferric Bromides, Cs„FeBr b H^O 

 and Rb^FeBi\HJJ. — The lirst of these salts was made with 

 the quantities of the constituent bromides about equal, the 

 second with 50 gr of rubidium bromide to 60 gr of ferric bro- 

 mide. The following are the analyses. 



Caesium 



Iron 



A. 

 35-76 

 .. . 8-05 



B. 

 35-60 

 7-93 



54-15 



2*84 



Calculated for 

 Cs 2 FeBr 5 H 2 0. 



35-95 

 7-56 



Bromine 



Water 



54-20 



2-52 



100-53 



A. 

 26-20 



... 8-86 



54-05 

 2-44 



Rubidium 

 Iron . . 



100-52 



B. 

 26-14 



8-99 

 62-12 



2-88 



100-00 



Calculated for 

 RboFoBr 5 H 2 0. 



26-51 



■ 8-6S 



Bromine 



62-13 



62-02 



Water 



2-90 



2-79 











100-09 



100-13 



100-00 



Both compounds were obtained in short doubly terminated 

 prisms. The caesium salt is comparatively stable while the 

 rubidium salt decomposes rapidly in the air. 



1 : 1 Caesium and Ammonium Ferric Bromides, CsFeBr i 

 and NH^FeBrflR^O. — A solution of 50 gr of caesium bromide 

 and 100 gr of ferric bromide gave the first of these salts in 

 slender needles. The second could not be obtained until 250 sr 

 of ferric bromide had been added to 50 gr of ammonium 

 bromide. Separate crops of each were analyzed with the 

 results given below. 



Caesium 26-02 



Iron 11-25 



Bromine 63-01 



100-28 



11-30 

 62-99 



Calculated for 

 CsFeBr 4 . 



26-13 

 11-00 



62-87 



100-00 



