H. L. Wells — Ccesmm- and Potassium- Lead Halides. 127 



CsPbCl 3 .— On gradually diluting the concentrated solution 

 of caesium chloride, such as was used in making the previous 

 salt, and dissolving lead chloride in it as before, a point is 

 soon reached where short prismatic crystals of small size and 

 of a pale yellow color are deposited on cooling. Three dif- 

 ferent crops of apparently pure crystals were analyzed. 



Caesium ... 31-33 

 Lead 4499 



Chlorine.. . 23-85 







Calculated 



Found. 





for CsPbCl 3 



30-54 



30-13 



29-79 



45-28 



46-29 



46-36 



23-75 



23-71 



23-85 



10017 99-57 10013 100*00 



CsPb 2 Cl 6 . — Experiments with still more dilute solutions, 

 carried out in a similar manner, gave, under wide variations 

 of conditions, this salt in the form of thin white plates which 

 were often several millimeters in diameter. These plates pre- 

 sented marked variations in habit, which were apparently due 

 to changes in the conditions under which they were made. 

 In two crops, of which A and B are the analyses, the plates 

 were uniformly rhomboidal in form. Two other crops, C and 

 D, were made up of lengthened plates, so twinned as to form 

 feathery aggregates. In another crop, E, made from a more 

 dilute solution than the others, the plates were apparently 

 square. 









Found. 







Calculated 





A. 



B. 



C. 



D. 



E. 



for Cs.PbjCl 



Caesium .. 



19-99 



18-44 



18-27 







18-45 



18-36 



Lead 



57-14 



57-16 



57'06 



56-98 



57-08 



57-16 



Chlorine - 







24-47 







24-52 



24'35 



24-48 



100-07 99-88 100-C0 



The three different habits in which this salt crystallizes are 

 so distinct in appearance that, before the samples were anal- 

 yzed, it was supposed that they were separate compounds. It 

 appears probable that the compound is at least dimorphous. 



The Caesium- Lead Bromides ; by P. T. Walden. 



Cs^PbBi\. — This salt is produced, in concentrated solutions, 

 similarly to the corresponding chloride. Like the latter salt it 

 forms white rhombohedrons. The crystals were usually not 

 over 1 or 2 mm in diameter. Two separate crops were prepared 

 and analyzed. 



