H. L. Wells — Caesium- Mercuric Ilalides. 227 



that there was no doubt about their homogeneity. Two crops 

 were analyzed. 



Calculated for 

 Found. CsHgsCln. 



Caesium. .. 8-68 8'51 8-73 



Mercury 65-59 65-64 



Chlorine. 24-97 25.63 



99-24 100-00 



A single recrystallization of this salt from water gave a 

 mixed crop of crystals and this, on repeating the operation, 

 gave CsHg 2 Cl 5 still containing a little of the original com- 

 pound. This last crop was analyzed. 



Calculated for 

 Found. CstIg 2 Cl 5 . 



Caesium 15-57 18-72 



The Double Bromides. 



All of these salts are white, or nearly so, except CsHgBr 8 

 which has a lemon-yellow color. This color is remarkable 

 since CsBr and HgBr 2 are both pure white. 



All of the double bromides yield CsHg 2 Br 5 on recrystallizing 

 them one or more times from water. It is to be noticed that 

 this salt belongs to a different type from the double-chloride 

 which is stable with water, but if alcohol is used for recrys- 

 tallizing this bromide, the salt corresponding to the chloride 

 just mentioned is deposited. 



Cs 9 IIgJBt\. — The preparation of this salt is exactly analogous 

 to that of the corresponding chloride, and it has the same 

 appearance. 



Calculated for 

 Found. Cs 3 HgBr 5 . 



Caesium 39-83 39*94 



Mercury 19-50 20.02 



Bromine 39-60 40'04 



98-93 100-00 



CsJIgBr^ is prepared similarly to the chloride, but the 

 limits of the conditions under which it is formed are much 

 wider. Like the chloride it usually forms very thin plates, 

 but they can sometimes be produced of sufficient thickness for 

 measurement. Three separate crops, made under considerably 

 different conditions were analyzed. 



