COMPOSITION OF CHAMBER DUST. 



711 



liectcil by the ismelteis, viho were imder the iuiines.siou that there was uo diflt'ereuee 

 betweeu the ilifl'erent i)arts of the same cake of shig, ami who used the ingenious 

 l)rocess of shelling out as a convenient way of breaking up the slag in small pieces 

 before resmeltiug. 



A comparison between specimens 28, 29, 30, and 31, or dolomitic slags, and speci- 

 mens 32, 33, 34, and 35, or calcific slags, shows that both kinds of slag contain sen- 

 sibly the same amount of silver. 



CHAMBER-DUST. 



The flue and cliamber dust of Leadville is always in the form of a coarse reddish 

 or blackish powder and full of very small particles of charcoal and coke. 



Very little has been done in Leadville with regard to a thorough examination of 

 these products, and all the information which could be obtained bears on the estima- 

 tion of lead and silver, and occasionally of silica and iron. In the following table is 

 condensed such information as could be obtained : 



Table XII. — Assays cf chamber-dust. 



In the description of each smelter the amount of flue-dust caught and the methods 

 of treatment of flue and chamber dust have already been given. 



Analijsi.'s. — An examination of the flue and chamber dust of the blast furnaces of 

 Leadville aftbrded such a flue opportunity for detectiug most of the substances dis- 

 seminated in the camp that the writer carried on quite exhaustive researches on these 

 products, and in order not to let anything escape he treated the dust with boiling 

 water and made a careful analysis of the soluble portion, then a careful examination 

 of the i)ortiou soluble in acids, and lastly a complete analysis of the portion insoluble 

 in acids. The results thus obtained ai'e extremely complicated and present an unnat- 

 ural appearance, but such as they are they give a clearer idea of the form under which 

 the dilfereiit compounds exist in the fumes, and of the reactions to which they owe 

 their origin, and no attempt was made to simplify the rejiorts. 



The labor expended on the examination of the lead fumes was rewai'ded by the 

 discovery of a new metal which appears to be distributed widely, though sparingly, 

 throughout the camp. In the elementary analyses the earthy and alkaline metals in 

 combinr.tioii with metalloids other than oxygen have been reported in tlie metallic 

 state. 



