Kraits and Cook — Iodyrite from Tonopah. 221 



The localities from which the material was obtained are not 

 indicated by Smith. We give below the average results of 

 Smith's analyses. Smith reports that aside from silver and 

 iodine, he found traces of copper and chlorine. Repeated 

 tests were made by us for bromine and chlorine, as also for the 

 metals lead and mercury, which would most likely replace the 

 silver. But in no case did we find the slightest trace of any of 

 them. 



The results of the analyses are as follows : 





Kraus and Cook 



Smith 



46-45$ 

 53-02 ' 



99-47 



Theoretical 



Ag_.._ 

 I .__. 



I 



.. 45*87^ 

 ._ 53-92 



.: 99-79 



II 



46-04$ 

 54-09 



Average 



45-95$ 

 54-01 



99-96 



45-97$ 

 54-03 



Total . 



100-13 



100-00 



We are indebted to Professor E. D. Campbell, Director of 

 the Chemical Laboratory of this University, for suggestions 

 relative to methods of decomposition and analysis. , 



Specific Gravity. 



Considerable variation exists in the values given for the 

 specific gravity of iodyrite or the artificial compound. This 

 variation is clearly shown by the following tabulation : 



Iodyrite. 



Bauer* _. _. 5 5 — 5-7 



Damourf 5-677 



Dana* 5-6 — 5-7 



Domeyko* 5*504 



Klockmann* ._ 5*707 



Naumarm-Zirkel* 5 - 6 — 5*7 



VomRath* 5-609 



Artificial Silver Iodide. 



Damourf. _ 5*669 



Deville 5-540 



Since the material which we used for the chemical analysis 

 proved to be exceptionally pure, we feel that the values we 

 obtained for the specific gravity are very reliable. Two 

 determinations were made on material which differed slightly 

 in color. There is also a slight difference to be noted in the 



* Loc. cit. 



f Eammelsberg, Handbuch der Krystallographisch-Physikalische Chemie, 

 I, 303, 1881. 



