36 H. L. Wells — Rubidium- Lead Halides. 



pale yellow color. It rapidly loses its water when exposed to 

 the air, undergoing a remarkable change of color. The pale 

 yellow compound quickly assumes an orange color, then the 

 color becomes almost like that of the original salt. It is evi- 

 dent that the salt, which contains two molecules of water, 

 loses a part of this, probably one molecule, with change of 

 color to orange ; then the remainder of the water is lost with 

 another change of color. It is interesting to notice, in this 

 connection, that the salt NH 4 PbClI 2 .2H 2 undergoes a similar 

 change of color, as far as the first step is concerned, on losing 

 one molecule of water when it is exposed to the air, but this 

 salt does not lose its second molecule at ordinary temperatures. 

 A sample of the rubidium lead iodide was rapidly pressed on 

 paper until some of the particles began to show a change of 

 color to orange. Water was determined in this sample from 

 the loss at 100°. 



Calculated for 

 Found. RbPM a .2H 2 



Water _ 6'09 5*07 



An air-dry sample gave the following analysis : 



Found. Calculated. 



Rubidium 13*29 12*70 



Lead 28-95 30-73 



Iodine _.. 56-80 56*57 



99-04 100-00 



Summary. 



The following table gives a list of the lead double halides 

 which have been prepared in this laboratory. All of them 

 were new compounds except KPbBr 3 .II 2 and KPbI 3 .2H 2 0, 

 these having been previously described by Remsen and Herty. 



4:1 2:1 



1:1 



1:2 



Cs 4 PbCl 6 

 CsJPbBr 6 



CsPbCl 3 

 CsPbBr, 

 CsPbI 3 



CsPb 2 Cl 5 

 CsPb 2 Br 5 



.... 2Rb 2 PbCl 4 .H 2 

 2Rb 2 PbBr 4 .H 2 



RbPblj2H 2 



RbPb 2 Cl 5 

 RbPb 2 Br 5 



.... K 2 PbBivH 2 



3KPbCl 3 .H 2 

 3KPbBr 3 .H 2 

 KPbBr 3 .H 2 U 

 KPbI 3 .2H 2 



KPb 2 Cl 6 

 KPb.Br. 



