Antimony with Rubidium. 



275 



proportion of six, eight and thirteen molecules of the former 

 to one of the latter. The crystals obtained on slowly cooling 

 these mixtures, with the exception of their strong • yellow 

 color, closely resemble the corresponding complex chloride. 

 If the solutions are rapidly cooled the salt separates in the 

 form of brilliant spangles. The average of the following 

 results gives a remarkably close ratio to that required for the 

 formula 23RbBr . lOSbBr,. 

 Analysis gave : 



Sample 

 From From of latter 



solution solution recrystallized 



6RbBr to 8RbBr to From solution from 



lSbBr s . lSbBr 3 . 13RbBr to lSbBr 3 . cone. HBr. 



Rb 26-66 26-16 26*92 26*60 26*71 26*39 



Sb 16-11 16*23 16-18 16*26 16*22 16-18 



Br 57*27 57*23 57*41 



Calculated for Calculated for Calculated for Calculated for 



23RbBr. 10SbBr 3 . 16RbBr . 7SbBr 3 . 9RbBr . 4SbBr 3 . 7RbBr . 3SbBr 3 . 



. Rb ... 26*55 26*47 26*27 26*74 



Sb 16*20 16-25 16-38 16*08 



Br 57-25 57*28 57*35 57*18 



Average of 

 analytical 

 results. Ratios derived 



Rb 26-57 -3107 or 23*03 or 16*12 or 9*21 or 6*90 



Sb 16-19 -1349 " 10-00 " 7'00 " 4'00 " 3*00 



Br 57*30 -7162 " 53*09 " 37*16 " 21*23 " 15*92 



It is to be noticed that this salt is formed within a much 

 smaller range of conditions than in the case of the chloride 

 and can only be recrystallized from strong hydrobromic acid 

 solutions. When recrystallized from moderately strong acid 

 a mixture of the salts 23 : 10 and 3 : 2 was obtained, but from 

 dilute acid a pure crop of the 3 : 2 compound separated. 



Recrystallized Recrystallized 



from strong from dilute Calculated for 



HBr. HBr. 3RbBr. 2SbBr 3 . 



Rb 25*54 21-89 21*08 



Sb 16-93 19-70 19*73 



Br _ 57*77 59*19 



The Double Iodide. 



3:2 Rubidium Antimony Iodide, SRbl. 2SbI s . — The for- 

 mation of this salt was observed when a solution of rubidium 

 iodide in hydriodic acid was saturated hot with antimony 

 iodide, it was also obtained from a solution of antimony iodide 

 in a large excess of rubidium iodide. The best crystals are 



