700 



GEOLUGY AND MINING INDUSTRY OF LEADVILLE. 



Table X. — Daily slag assays — Continued. 



The above figures show the influence of the numerous elements with which the 

 smelter has to contend. The influence of the head smelter and of the furnace is indi- 

 cated by the fact that Furnace No. 1 gives nearly always the slag richest in lead and 

 silver. The influence of the silver contents of the bullion is clearly seen in the cases 

 in which the richest slags correspond to the richest bullion. The overpowering in- 

 fluence of the composition of smelting charges is forcibly indicated in the cases in 

 which poorer slags correspond to a richer bullion. 



Specific gravity of slag — At Messrs Cumming& Finn's smelter the specific gravity 

 of slag from each furnace is determined daily. It results from a very great number of 

 determinations made by the superintendent, Mr. MacFarlane, by means of the Jolly 

 specific-gravity spring-balance, described in Section I, that the average specific gravity 

 of slag varies between 3.7 and 3.8. 



Dr. M. W. lies has obtained an average of 3.691 from a hundred determinations 

 made on unusually fine runs at the Grant smelter. 



