P. T. Walden — Double Chlorides and Bromides, etc. 289 



A. 



Ammonium 3*98 



Iron 13-48 



Bromine 74-85 



Water 7 -69* 







Calculated for 



B. 



C. 



NH 4 FeBr 4 2H a O. 



3-92 



3*83 



4-19 



13-59 





13-02 



74-71 





74-42 



7-78* 





8-37 



100-00 100-00 100-00 



As the ammonium salt is so deliquescent that no satisfactory 

 determination of water was possible, it was taken by difference 

 and it is believed that the results warrant the acceptance of 

 the formula as written above. Great care was exercised in an 

 attempt to prepare a 2 : 1 ammonium bromide but without 

 success. NH 4 FeBr 4 2H 2 and simple ammonium bromide were 

 finally crystallized out together in the same solution. This is 

 regarded as good evidence that no salt of a type higher in 

 ammonium exists. 



Ferro-f erne Salts : BoBrFeBr£FeBr£H^O and KBrFe 

 Br3FeBr 3 ZH^O. — While endeavoring to obtain a double fer- 

 ric bromide with potassium a dark green body separated from 

 a solution containing an excess of bromine, which gave a 

 black hydroxide with ammonia. This was considered so 

 remarkable that an effort was made to prepare corresponding 

 salts with the other alkali-halides and ammonium, under the 

 same conditions. This attempt resulted in the formation of 

 only one other compound of the same kind, that with rubid- 

 ium. The ferrous iron in those salts was determined by titra- 

 tion in the presence of hydrochloric acid with a standard 

 potassium dicromate solution. It was found to be impossible 

 to determine water satisfactorily on account of the extreme 

 instability of both salts. It was therefore taken by difference. 

 The rubidium salt resulted from the bringing together in solu- 

 tion of 50 gr of rubidium bromide and 150 sr of ferric bromide, 

 the potassium salt from a solution of 50 sr of potassium bro- 

 mide and 250 sr of ferric bromide. Below are the analytical 

 results, A, B, and C being separate crops. 













Calculated for 





A. 



B. 



C. 



RbBr 



. FeBr,.2FeBr 3 3H 2 0, 



Rubidium 



7*25 









8-32 



Ferrous iron .. 



5-17 



5-16 



5-53 





5-45 



Ferric iron 



11-10 



10-71 



10-13 





10-90 



Bromine.. 



68-83 



68-37 



(38-48 





70-07 



Water 



7-65* 









5 26 





100-00 



10000 





* "Water by difference. . 







