726 



GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



The writer has not 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, iu the same manner as 

 those of the mattes : 



TABLE XV. ASSAYS OF HEARTH ACCRETIONS FROM GKAXT SMEI.TKII. 



Discustiion. The assay of silver iu the slag-matte indicates to some extent tin- 

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

 No. 1 contains more matte than 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 deprived of its silver by the matte. 



Shaft accretions As has already been staled, the shaft accretions have nothing 

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

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

 parts 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 those 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-trauslucid crystals of chloro-bromide of lead found by Dr. 

 M. W. lies in one of the furnaces at Grant smelter, between the main cast-iron plate 

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

 lies and found to contain 



Chlorine 10.34". 



Bromine 83.321 



Lead 63.927 



99. 



A small quantity of the crystals "^ere kindly forwarded to the writer by Dr. 

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



