2 John White 



Judg-ing from the results obtained during the present investiga- 

 tion, there is every indication that Carius's results and formula 

 are substantially correct. About ten years later, Tommasi,^ ap- 

 parently in ignorance of the work of Carius, succeeded in dissolv- 

 ing the iodid of lead in potassium acetate solution, and from this 

 obtained a crystalline compound to which he gave the formula 



^'°*{g%o,+^^'«'''- 



It will be seen later in this article that, although Tommasi did 

 not ascribe the correct formula to his compound, he in all 

 probability had a substance of definite composition. In the 

 same article he calls attention to the fact that the iodid is 

 soluble in the acetates of other bases, but he was unable to 

 isolate any of these and so to prove that definite compounds had 

 !been formed. 



Observations similar in character to the above, but which 

 led to nothing of moment, were also made by Nickles- and 

 Field.^ 



The paucity of the literature upon the subject and the uncer- 

 tainty of the results obtained suggested the advisability of under- 

 taking a thorough investigation with the object of determining 

 the general character of this and allied reactions and the nature 

 of the compounds, if any, which are formed. Some of the results 

 thus far obtained are recorded in the following pages. 



The iodid was selected as the best of the halogen salts of lead 

 to experiment upon in the beginning, for, although the resultant 

 compound might prove less stable, any change of color could 

 be more easily detected than with either the bromid or chlorid. 

 This has proved to be the case, for in practically every 

 case the salt obtained was white; any decomposition would 

 give rise to lead iodid which could be easily recognized by its 



^Ann. chim.phys. [4], XXV, 168 (1872); Bull. soc. chivi., XVII, 357. 



2Co;«/ii?. r^wfl'., LVI, b88 (1863). 



8/. Chem. Soc. (London), XXVI, 575 (1873). 



308 



