26 Wells and Penfield — Series of Caesium Trihalides. 



Calculated for 

 Found. CsClBrl. 



Caesium... 34-24 35-42 



Chlorine 9*36 9-45 



Bromine 19-96 21-30 



Iodine 32-36 33-83 



If a large excess of bromine is used, an impure product 

 results as is shown by the following analysis of a sample thus 

 made : 



Found. 



Caesium 36*1 1 



Chlorine 9-36 



Bromine 27*70 



Iodine 24*83 



On attempting to recrystallize the CsClBrl a product of a 

 darker red color is formed, sometimes accompanied by the 

 separation of some iodine. The following analyses were made 

 of products of recrystallization : 



" A " was from a single recrystallization. " B " was recrys- 

 tallized three times, a little alcohol being added the last time 

 to keep iodine in solution. " C" was recrystallized.five times, 

 each time with the addition of a large excess of bromine. 



Calculated for Calculated for 

 A. B. C. CsClBrl. CsBrJ. 



Caesium. ._ 32-69 33-22 .... 35-42 31-67 



Chlorine .. 3-32 5*02 2*70 9*45 0' 



Bromine .. 31-56 28-30 32*50 21-30 38-09 



Iodine 30-91 31-78 30-99 33-83 30-24 



These analyses show that the recrystallized body approaches 

 CsBr 2 I, but that a part of the chlorine is very tenaciously held. 

 The excess of bromine used in the case " C " had apparently 

 no effect, probably because caesium and iodine were present in 

 equivalent quantities, whereas, in the case previously given, in 

 which an excess of bromine was used in presence of much 

 caesium chloride in preparing the body, there was evidently a 

 contamination with CsClBr 2 . 



CsClJ. 



This body is dimorphous, the form apparently depending 

 upon the presence or absence of a large excess of caesium 

 chloride in the solution from which it crystallizes. 



The rhombohedral variety is usually obtained by adding 

 iodine in the proportion of one atom- to one molecule of 

 caesium chloride dissolved in about ten parts of water, then 

 passing chlorine into the liquid heated nearly to boiling until 

 the iodine just dissolves, and finally cooling. If an excess of 



