694 



GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



Analyses The writer has made in the laboratory of the Survey the two following 

 analyses of bullion : 



Analysis XXII. Specimen of bullion taken from the furnace at the La Plata 

 smelter. This bullion is soft, with a clean surface. 



Analysis XXIII, Mixture of equal parts of bullion from the following smelters : 



Names of smelters. Remarks. 



Billing & Eilers Sample from one car-load, weighing about 11 tons; soft, with a clean sur- 

 face. 



Gumming & Finn Sample from one car-load, weighing abontlOtons; somewhat hard, with 



clean surface. 



California One specimen from one furnace. 



Elgin One specimen from one furnace. 



Grant Two specimens from two furnaces. 



Gage, Hagamau & Co Sample from one car load shipped in December, 1879. 



Harrison One specimen from one furnace. 



La Plata One specimen from one furnace. 



Ohio and Missouri One specimen from one furnace. 



ANALYSES XXII AND XXIII. BULLION. 



Discussion Analysis XXIII enabled the writer to detect the presence of a great 

 number of metals, some of which, like tin, were not even suspected to exist in Lead- 

 ville, inasmuch as the sample analyzed represents ores from nearly every mine in the 

 region. While investigating this sample of bullion it was observed that part of the 

 silver exists there in the state of sulphide. Some of the lead, as might be anticipated, 

 is also in the state of sulphide. This is very easily demonstrated in the following 

 manner: The bullion is dissolved in weak nitric acid; the unattacked residue is both 

 yellow and black. The yellow portion is sulphur from sulphide of lead, which is easily 

 attacked by weak nitric acid with separation of sulphur; the black portion is formed of 

 sulphide of silver, which is not touched by weak nitric acid. Neither the relative pro- 

 portion of silver existing in bullion in the metallic state, nor the amount of lead as sul- 

 phide, was determined, because this kind of research would have led too far ; but it 

 would seem to be sufficient to call the attention of smelters and refiners to the fact. 



