28 Wells and Penfield — Series of Caesium Trihalides. 



The analyses of two products are given below. The "pre- 

 cipitate" resulted from adding bromine to a cold caesium 

 chloride solution, and, being finely divided as well as the most 

 unstable compound of the series, it suffered a considerable 

 amount of decomposition although time was not taken to dry 

 it thoroughly. 



Found. 



, * > Calculated for 



Precipitate. Crystals. CsClBr 2 . 



Caesium 40-62 42-14 40*49 



Chlorine 12-64 13-24 10-81 



Bromine 39'61 42*93 48-70 



Water 6-45 1*72 0- 



99-32 100-03 100-00 



GsCkBr. 



This substance may be made by adding the calculated 

 amount of bromine to a solution of caesium chloride in five 

 parts of water, warming enough to keep CsClBr 2 in solution, 

 and passing chlorine in excess. 



Calculated for 

 Analysis gave CsCl 2 Br. 



Caesium 46*25 46*83 



Chlorine 24*15 25-00 



Bromine 26-05 28-17 



[CsCl r ] 



Efforts to prepare this substance by passing chlorine into 

 saturated aqueous solutions of caesium chloride cooled by a 

 freezing-mixture did not succeed. It was noticable that the 

 compound CI 5H 2 was not formed under these circumstances. 



Other Trihalides. 



Johnson's KI 3 * is undoubtedly analogous to the caesium 

 compounds. An investigation of this and other potassium 

 trihalides as well as the corresponding rubidium compounds 

 is now in progress in this laboratory, and an effort will be 

 made to prepare similar compounds with still other metals. 



The compound KI 2 (CN)f and the body NH 4 I 3 , which John- 

 son describes;}: as very similar to KI 3 , should be mentioned in 

 this connection. 



There have been described a great number of trihalides of 

 both natural and artificial organic bases. These are mostly 

 triiodides but there are among them a number of tribromides 



*J. Chem. Soc, 1877, i, 249. 



fLanglois, Ann. Chim. Phys., [Ill] lx, 220. \3. Chem. Soc, 1878, 397. 



