H. L. Wells — Caesium- and Potassium-Lead Halides. 138 



ZKPbBr % . H^O. — The conditions under which this salt can 

 be made are rather narrow, and these conditions encroach upon 

 those of the preceding compound, so that small differences in 

 the amounts of lead chloride used or in the temperature of 

 the solution are sufficient to cause the formation of the other 

 salt. It forms brilliant, colorless, lozenge-shaped crystals 

 which can be easily distinguished from the other compound. 

 The crystals which were obtained sometimes had a diameter of 

 2 or 3^ m . 



The crops analyzed were made under the following condi- 

 tions : 



Volume 

 KBr. PbBr 2 . Volume. for lgKBr. 



A 500S 130S . 950 cc 1-^ 



B 500 J 30 1050 2 T V 



C 500 140 900 1 T V 



D 500 120 1050 2 T V 



E 500 120 1125 2^ 



The analyses were as follows : 



K. Pb. Br. H 2 0. 



A 8-44 41-91 1-29 



B 8-02 42-71 48-95 1'62 = 101*30 



C i 8-60 41-61 49-16 1-60 = 100-97 



D 8'08 42-69 48-91 1-14 = 100-82 



E 42-61 1-17 



SKPbBr^H ?) 1 7 ' 95 42 '° 6 48 '" 1-22=100-00 



The salt is stable in the air. A sample, after standing seven 

 days over sulphuric acid, lost only O01 per cent. The water 

 is given off very slowly at 100°. 



KPbBr % .H i O. — This salt was described by Remsen and 

 Herty. At summer temperature, about 25°, I was unable to 

 obtain it, but by placing the mother-liquors from the preced- 

 ing salt in an ice- chest, beautifully crystallized crops of it 

 were obtained. 



Its formation was also noticed at laboratory temperatures 

 when the weather was somewhat cooler than in mid-summer. 

 It form? prismatic crystals. Some of those obtained were 

 about 10 mm long and 2 mm in diameter. Two crops were 

 analyzed. 



Calculated for 

 Found. KPbBr 3 . H 2 0. 



Potassium 8-24 7*90 7-76 



Lead 4] -23 41-20 41-06 



Bromine 47*81 47'61 



Water 3-28 3-64 3*57 



100-56 



100-00 



