H L. Wells — Ccesium- and Potassium- Lead Halides. 121 



Art. XYI. — On the Caesium- and the Potassium-Lead 

 Halides ; by H. L. Wells. 



As a continuation of the work on double halides, in this 

 laboratory,* a study of the caesium-lead salts has been under- 

 taken by Messrs. G. F. Campbell, P. T. Walden and A. P. 

 Wheeler. These gentlemen have carried out the investigation 

 with much enthusiasm and skill, and I take pleasure in express- 

 ing my obligations to them. They have established the fol- 

 lowing salts : 



Cs 4 PbCl 6 Cs 4 PbBr f 



CsPbCl 3 CsPbBrJ CsPbI 3 

 CsPb 3 Cl 5 CsPb 2 Br 5 



These results showed the existence of , three types of lead 

 double halides, the first of which fails to conform with 

 Remsen's lawi concerning the composition of this class of 

 bodies. 



Since the recent investigations of Remsen and Herty§ had 

 indicated the existence of only a single type of potassium-lead 

 halides, a new investigation of these seemed desirable, espe- 

 cially since these authors had denied the existence of Boullay's 

 salt,|| K 4 PbI 6 , which corresponds to one type of the new 

 caesium compounds. I have, therefore, undertaken this work 

 and, as a result, have obtained the following salts : 



K 2 PbBr 4 .H,0 



3KPbCl 3 .H 2 | 3 lpbi;>;5 2 o^ Kp bI,.2H,0 

 KPb„CL KPbBrV 



It is to be noticed that neither Boullay's iodide nor any 

 corresponding chloride or bromide was obtained among these 

 salts. On the other hand, the compound K 2 PbBr 4 . H Q be- 

 longs to a type which had not been discovered among the 

 caesium salts, so that, taking the caesium and potassium series 

 together, the existence of four types of double lead halides is 

 shown. 



The compound K„PbBr 4 , the anhydrous form of the salt 

 just mentioned, is ascribed to Lo'wig,^[ but although iodides 

 belonging to the same type have been described, K 2 PbI 4 . 4H 3 

 by Ditte** and K 2 PbI 4 . 2H 2 by Berthelot,ft neither Remsen 



*This Journal, III, xliv, 155, 157 and 221. 



f This compound is dimorphous. % Am. Chem. Jour., xi, 296. 



§ Am. Chem. Jour., xiv, 107. || Ann. Chim. Phjs., II, xxxiv, 336 (1827). 



•fGmelin's ••Handbook," English Ed. of 1850, v, 162. 



**Arm. Chim. Phys., V, xxiv, 226, 1881. 



ff Ann. Chim. Phys., V, xxix, 289, 1883. 



