222 Kraus and Cook — Iodyrite from Tonopah. 



results. The determinations were made with the common 

 specific gravity flask at room temperature. 

 The results are : 



Dark variety ..__ 5*519 



Light variety 5*504 



Average 5*5115 



These values are much lower than those given by Damour, 

 Dana, vom Rath, Klockmann, and Naumann-Zirkel, but agree 

 fairly well with the determinations of Domeyko on natural 

 crystals and with the value given by Deville for the artificial 

 compound. Our results also fall within the limits set by 

 Bauer. 



Mineralogical Laboratory, 



University of Michigan, 

 December 22, 1908. 



