of some Chilian Minerals. 105 



which have been filled in with metallic matter, doubtlessly injected 

 at the time of the eruption of the dioritic rock in close proximity. 

 The bismnthic silver I found in conjunction with Domeykite, 

 which latter is frequently difficult to separate entirely from it; 

 otherwise, on examination with a magnifier, the bismuthic silver 

 appeared to be quite free from any extraneous mineral substance. 

 The specimen analysed by Domeyko afforded to him 



Silver 60-1 



Bismuth 10' 1 



Copper 7*8 



Arsenic 2*8 



Gangue 19-2 



100-0 

 In this analysis the copper and arsenic are so nearly in the 

 proportion of Domeykite (which would require 7*2 copper to the 

 2*8 arsenic present) that it may safely be considered to be the 

 case. Deducting therefore this amount, as well as the gangue, 

 the proportion of silver and bismuth expressed in percentages 

 will stand as follows : — 



Silver 85-61 



Bismuth .... 14*39 



100-00 

 results which would appear to indicate the formula Ag 12 Bi, 

 which upon calculation should contain 



Silver 86-17 



Bismuth .... 1383 



10000 

 The mineral called bismuthic silver, and classed under that 

 head by Dana*, is in reality nothing more than a mere mixture 

 of various metallic sulphides. The analysis by Klaproth is 

 given as 



Sulphur 16-3 



Bismuth 27-0 



Lead 33'0 



Silver 15-0 



Iron 4-3 



Copper 0-9 



It is only necessary to calculate the equivalent amount of sul- 

 phur requisite to form sulphides with the respective quantities 

 given of each metal, to see at a glance that the amount of sulphur 



* Dana's 'Mineralogy,' 4th edit. vol. ii. p. 16. 



