430 Wells and Walden — Double Chlorides , Bromides, etc. 



3:1 Ccesium- Cadmium Iodide, Cs z CdI b . — This salt crystal- 

 lizes beautifully in large, stout, twinned prisms which show a 

 variety of habits. Some of the crystals obtained were as 

 much as 50 mm in diameter. Its formation was observed when 

 182 g of caesium iodide and 6 5 g of cadmium iodide were dis- 

 solved in sufficient water to make a volume of 200 cc . 



Four crops gave the following results on analysis : 



Found. Calculated for Cs 3 Cdl 5 . 



Cs . 34-85 34-89 34*78 34'82 



Cd 9-78 9-79 9-84 9*55 9*77 



1.. 55-23 55-35 55-32 55*36 55"41 



99-86 10003 99-94 100-00 



%: 1 Ccesium- Cadmium Iodide, Csfidl^. — This, like the 

 corresponding mercuric salt, crystallizes in nearly square plates, 

 in prisms and in intermediate forms. Some of the plates ob- 

 tained were 50 or 75 mm in diameter. It can be prepared by 

 recrystallizing Cs 3 CdI B from water, and as the proportion of 

 cadmium iodide is increased, it continues to form until the 

 ratio of cadmium to caesium has almost reached 1 : 1. The 

 range of its formation is, therefore, much greater than that of 

 the corresponding chloride and bromide, and it also differs 

 from these in being recrystallizable from water. Three dif- 

 ferent samples were analyzed. 



Found. Calculated for Cs 3 CdI 4 . 



Cassium 29*85 30-29 30-23 30'03 



Cadmium 12*56 12'53 12-46 12*64 



Iodine 57*27 57*42 57*33 



100*09 100*11 100*00 



1 : 1 Ccesium- Cadmiicm Iodide, CsCdI % .lift. — This salt 

 forms thin plates, often 20 to 80 mm in diameter. It is the only 

 hydrous caesium-cadmium halide that we have obtained, and it 

 is stable when exposed to the air at ordinary temperatures. 



It was considered doubtful whether the corresponding 

 caesium mercuric iodide* contained a molecule of feebly com- 

 bined water or not, but since both the cadmium and mercuric 

 salts crystallize in thin plates, it is now believed, from analogy, 

 that the mercuric compound was really hydrous. 



The compound under consideration is formed under wide 

 limits of conditions when the cadmium present is atomically 

 equivalent to or in excess of the caesium. It can be recrvstal- 

 lized from water. The samples analyzed were prepared under 

 widely varying conditions. 



* This Journal, xliv, 230. 



