Wells and Penfield — Series of Caesium Trihalides. 27 



chlorine is used, the body CsClJ is formed corresponding to 

 KC1J discovered by FilhoL* This new caesium compound 

 will be described in a future article in connection with several 

 other new bodies of the same class. 



The orthorhombic variety of CsCl 2 I can be obtained by 

 using three or four times as much caesium chloride as in the 

 other case, the other conditions remaining unchanged. 



The following analyses of two separate products of each of 

 the two varieties were made. 



Rhombohedral. Orthorhombic. Calculated for 



Found. Found. CsCl 2 I. 



Caesium 39-20 39-92 38-43 40-00 40-18 



Chlorine 20*72 21-08 19-78 20*75 21-45 



Iodine 37*81 38-21 38'97 38-88 38-37 



On recrystallizing either form of this substance, from solu- 

 tion in hot water, the rhombohedral variety is usually formed, 

 owing to the lack of an excess of caesium chloride. It is not 

 unusual, however, to obtain at first, as the solution cools, slen- 

 der needles evidently of the orthorhombic variety, which 

 afterward become surrounded by rhombohedral crystals. 



UsBr s . 



To make this substance, one half the calculated amount of 

 bromine is added to a solution of one part of caesium bromide 

 in three parts of water, the whole is heated with vigorous 

 shaking until the liquid bromine disappears and then slowly 

 cooled. Crystals gave on analysis : 



Calculated for 

 Fourid. CsBr 3 



Caesium 35-12 35*66 



Bromine 61*53 64*34 



In preparing this body, there usually remains, when the 

 liquid bromine disappears on heating the solution, a heavy red- 

 dish liquid much lighter in color than bromine. It is without 

 doubt a higher polybromide and it probably corresponds to 

 the easily fusible substance already mentioned as a probable 

 higher polyiodide. An investigation of its composition will 

 soon be made. 



Cs Cl£r a . 



The formation of this body was mentioned at the beginning 

 of this article in connection with the discovery of the new 

 series of salts. It can be made by adding about one half the 

 theoretical bromine to a solution of caesium chloride in about 

 five parts of water, dissolving by heat and cooling. 



*Michalis, ''Anorgan Chem.," 3, 102; Gmelin-Kraut, II, ], 82. 



