of some Chilian Minerals, 109 



In considering the composition of the first of these, or metallic 

 granules, the ratio of the arsenic to the other bases is nearly 

 that of the formula Ag 6 As, which would give the following per- 

 centage composition : — 



Arsenic .... 10*37 

 Silver 89-63 



100-00 



And if we look upon the silver as being in small part replaced by 

 the mercury, iron, and cobalt found in the analysis, the formula 

 Ag, HgFe, Co) 6 As doubtless represents the constitution of 

 these metallic granules. 



The second product (the metallic powder left behind in wash- 

 ing) is somewhat more complicated : deducting the gangue, 

 and recalculating the results to percentages, we obtain the com- 

 position of the clean metallic powder as follows : — 



Silver 43-93 



Iron 15-24 



Cobalt 9-17 



Nickel 0-63 



Arsenic .... 29'92 



Antimony .... 1*11 



100-00 



If now we unite the nickel with the cobalt as well as the arsenic 

 and antimony, on calculation, the equivalents which approximate 

 most closely to the terms of the analysis are Ag 4 , Fe 5 , Co 3 , and 

 As 4 , which, expressed in percentages, gives 



Silver 44-96 



Iron 14-58 



Cobalt .... 9-24 



Arsenic .... 31-22 



100-00 



The equivalents of the metals being to those of the arsenic in the 

 ratio of 12 to 4, we have the formula (AgFeCO) 3 As, a tri- 

 basic arsenide of silver with iron and cobalt, which represents 

 the constitution of this compound. 



We have now only to dispose of the black sediment, which 

 was least in specific gravity. Deducting from the analysis 

 already given of this product the gangue, and recalculating the 

 percentages of the other components, the analysis will then stand 

 as follows : — 



