Bromides and Iodides of Ccesium and Cadmium. 427 



concentration is often an important factor in determining the 

 salt produced. 



The three 1:1 compounds CsCdCl,, CsCdBr, and CsCdl,. 

 H 2 and also the 2 : 1 iodide Cs 2 Cdl 4 are capable of being 

 recrystallized from water unchanged. The salt Cs,CdCl 4 , 

 when dissolved in water, yields CsCdCl 3 , the two bromides 

 Os 3 CdBr 5 and Cs 2 CdBr 4 yield CsCdBr, while the iodide Cs.CdI. 

 gives Cs 2 CdI 4 . These facts show that the salts having the 

 larger proportions of caesium require the presence of an excess 

 of caesium halide for their formation. The 1 : 1 salts all crys- 

 tallize unchanged from extremely concentrated solutions of 

 the corresponding cadmium halides. 



All the salts are colorless. A pale violet color noticed in a 

 few crops of the bromide Cs 2 CdBr 4 is supposed to have been 

 due to some unknown foreign substance. 



The solubility of the analogous salts in water or in saline 

 solutions evidently increases from the chlorides to the iodides. 

 The iodides consequently yield the largest crystals while the 

 chlorides give the smallest. 



Jlefhods of Analysis. —The products were carefully exam- 

 ined, and nothing was analyzed that was not homogeneous. 

 The crystals, which, in several instances, were large and fine 

 and in no case hygroscopic, were freed from mother liquor 

 with great care by pressing and crushing them on smooth 

 filter-paper. They were then simply air-dried for analysis. 



Cadmium was precipitated as sulphide, this was dissolved in 

 hydrochloric acid containing bromine, and after the free acid 

 had been removed by evaporation, the cadmium was precipi- 

 tated with potassium carbonate solution and cadmium oxide 

 was weighed on a Gooch filter. The caesium in the filtrate 

 from the cadmium sulphide was determined as normal sul- 

 phate. The halogens were determined in separate portions by 

 the usual gravimetric method. 



In every case, at least two separate crops of a salt were 

 made and analyzed, so as to avoid any chance of mistakes aris- 

 ing from mixtures. 



2:1 Ccesium- Cadmium Chloride, Cs^CdCl^. — This salt is 

 produced as a precipitate when a solution of cadmium chloride 

 is added to a concentrated caesium chloride solution. The 

 precipitate dissolves upon warming the liquid, and crys- 

 tallizes out in very small, rectangular plates when the solu- 

 tion is cooled. Its formation was observed when 50 s of 

 caesium chloride and 3 g of cadmium chloride were used, and 

 it continued to be produced with the same amount of caesium 

 chloride until the amount of cadmium chloride had been 

 increased to 18 g , at which point the 1 : 1 salt began to form. 

 The salt is very sparingly soluble in caesium chloride solutions 



