Bromides and Iodides of Caesium and Cadmium. 429 



The following analyses of separate crops were made. !No. 

 IV was a simple of the pale violet variety. 



Found. Calculated for 



I. II. III. IV. Cs 2 CdBr 4 . 



Cs. 40-46 40-53 40-46 38-11 



Cd 14-55 14-62 14-68 14*78 16*05 



Br 45*12 44-97 45*04 45-04 45*84 



100*13 100*12 100*28 100*00 



Although the analyses agree well among themselves, it is 

 noticeable that they vary considerably from the calculated com- 

 position. This disagreement is probably due to contamination 

 with caesium chloride, resulting from the large surface exposed 

 by the slender crystals and the concentration of the mother- 

 liquor. Moreover, analogy with the chloride and iodide makes 

 the simple formula Cs 2 CdBr 4 far more probable than the com- 

 plicated formula Cs 7 Cd 3 Br ]3 with which the analyses corre- 

 spond. 



1:1 Caesium- Cadmium Bromide, CsCdBr r — The condi- 

 tions under which this compound is formed are very wide in 

 range, for it is produced by recrystallizing Cs s CdBr 5 and it 

 continues to appear as cadmium bromide is added until the 

 solution is saturated with this very soluble salt. 



The compound is evidently dimorphous. One form occurs 

 as a crystalline precipitate, apparently isometric in form, under 

 narrow limits of conditions when caesium bromide is in excess, 

 being produced when Cs,CdBr 6 is recrystallized from water. 

 The other form occurs in well crystallized prisms, and is 

 obtained when Cs 9 CdBr 4 is recrystallized and when cadmium 

 bromide is in excess of this proportion. It is interesting to 

 notice that we have described a caesium-lead bromide* of this 

 type, CsPbBr,, which is dimorphous, and that one of us has 

 described the dimorphous mercuric compounds,*]* CsHgCl, and 

 CsHgBr 3 , which also belong to the same type. 



Below are the analyses of four separate samples. Number 

 IV is the granular, isometric salt, the others represent the 

 prismatic compound. 



Found. Calculated for 



I. II. III. IV. CsCdBr 8 . 



Cs 27*67 27-48 27*95 27*42 



Cd 22*97 23*08 22*87 22*92 23-09 



Br ... ... 49-49 49-42 49*33 4930 49*49 



100*13 99*98 100*17 100-00 



*This Journal, xlv, 128. f Ibid., xliv, 225 and 223. 



Am. Jour. Scl— Third Series, Vol. XLVI, No 276.— Dec, 1893. 

 30 



