726 



GEOLOGY AXD MIXING IXDDSTKY OF LEADYILLE. 



The writer Las uot pursued further the investigations of these hearth accretions 

 for the reason that the elements which constitute them have already been fully exam- 

 ined and discussed. The following assays were made however, in the same manner as 

 those of the mattes : 



Table XV. Assays of hearth accuetioxs from Grant s.meltee. 



Separates into — 



Slag-matte powder . 

 Metallic grains 



Silver contents. 



Crude hearth accretion ounces per ton. 



Slag-matte powder do 



Metallic grains do 



Gold contents. 



Crude hearth accretion ounces per ton . 



Slag-matte powder do 



Metallic gr,iiDs do 



63.06 

 36.94 



47.G916 I 

 26.8 j 

 112. 8 ' 



Trace 

 Trace 

 Trace 



81.0473 

 16. 125 

 193. 50 



Trace 

 Trace 

 Trace 



Discussion. — The assay of silver in the slag-matte indicates to .some extent the 

 relative proportion of slag and matte in the hearth accretion, it being evident that 

 No. 1 contains more matte thau No. 2. The fact that the poorest bullion, No. 1, cor- 

 responds to the richest accretion, and the richest bullion, No. 2, to the poorest accre- 

 tion, confirms the similar observation made on the mattes, and seems to indicate that 

 bullion is dejnived of its silver by the matte. 



Shaft accretions — As has already been stated, the shaft accretions have nothing 

 in common with hearth accretions. Shaft accretions generally result from the con- 

 densation of sublimated products. They form thick incrustations against the lower 

 l^arts of the walls of the shaft of blast-furnaces, and occasionally line the whole of 

 the shaft. At Gage, Hagaman & Co.'s the writer has seen a small round furnace 

 entirely lined, from the top of the water jackets to within six inches of the feed-hole., 

 with accretions a foot thick. A very complete collection of tho.se products was made, 

 as it was expected that in them would be found a great concentration of the metals 

 which occur iu minute quantities in the ores. 



Before describing normal accretions the writer would say a few words concerning 

 some pretty yellowish semi-translucid crystals of chlorobromide of lead found by Dr. 

 M. \V. lies in one of the furnaces at Grant smelter, between the main cast-ii'on plate 

 support of the furnace and the masonry. These crystals were analyzed by Dr. 

 lies and found to contain — 



Chlorine 10. 34:> 



Bromine 2."). 3-il 



Lead 63.927 



99. 593 



A small quantity of the crystals were kindly forwarded to the writer by Dr. 

 Hes, and were examined qualitatively ; in these were found, besides chloride and bro- 



