484 Wells, Wheeler and Penfield — Rubidium, and 



Calculated for 

 Analysis gave EtbBr . Br... 



Rubidium 25*86 2626 



Bromine... 73*09 73 73 



Rb CI . Br„. 



This body is prepared by adding bromine to a warm, satu 

 rated solution of rubidium chloride until some bromine re- 

 mains undissolved and cooling to a low temperature. The 

 compound crystallizes well, but it is the most unstable of the 

 seven rubidium tribalides that have been prepared, and, 

 although it was not fully dried, the sample used for analysis 

 suffered a considerable amount of decomposition. 



Calculated for 

 Analysis gave RbCl . Br 2 . 



Rubidium 32-57 30-42 



Chlorine 14-46 14-44 12'63 



Bromine 49-04 49-40 56'93 



In one attempt to prepare this trihalide too much water was 

 used and it was necessary to evaporate off the bromine and 

 concentrate the solution. This operation was repeated several 

 times, after fresh additions of bromine, before the proper con- 

 ditions were arrived at, and the product finally obtained was 

 contaminated with RbBr . Br 2 , as is shown by the following 

 analyses : 



Calculated for Calculated for 

 Found. RbCl . Br 2 . RbBr . Br 2 . 



Rubidium 28-78 30-42 26*26 



Chlorine 7*66 6-94 12*63 0* 



Bromine 60-92 61*37 56-93 73=73 



We have found by experiment that rubidium chloride is 

 partly changed to bromide by evaporating an aqueous solution 

 of it with bromine.* This explains the formation of the 

 RbBr . Br 2 . 



RbCl. ClBr. 



This compound can be prepared by adding 33 g. of bromine 

 to a saturated solution of 50 g. of rubidium chloride, passing 

 chlorine to saturation into the slightly warmed solution, and 

 cooling to a low temperature. The substance is usually de- 

 posited in the form of very large, light yellow prisms. 



Calculated for 

 Analysis gave RbCl . ClBr. 



Rubidium 35-42 ' 3541 36-15 



Chlorine 29-27 28-96 30-02 



Bromine 31-56 31*39 33*82 



* Tbis is in accordance witb tbe results of Potilzin referred to by Mendelejeff 

 in bis " Grundlagen der Cbemie " (German ed., 1891) p. 538. 



