On the AJfay'ing of Iron Ores, 8cc. 179 



The procefs of depriving ores of their metal by fufioa in 

 the aflay-furnace, and that part particularly relating to iron, 

 which I mean to make the principal fubjeft of this paper, 

 lead me more immediately to make theie obfervations. With 

 the manufafturer, in general, the ufes and propriety of the 

 aflay-furnace are feldom admitted, or, at baft, are refl;ri£ted to 

 fuch narrow limits as to be only capable of afcertaining the 

 quantity of iron contained in ore or iron-ftone. The che- 

 mift, on the other hand, intent only upon eifefting his ope- 

 ration, and of giving accuracy to the refult, confines his ob- 

 fervations to a certain chain of fcience, and feldom or never 

 confiders manufailures as the ultimate and happy end towards 

 which his labours fliould be dire6led. 



With whatever deference and refpeft we look up to the 

 names of men celebrated for their indefatigable zeal and in- 

 duftry in the caufe of fcience, and with whatever fatisfaftioi;! 

 we reft upon the refult of their labours as to truth ; yet, in 

 general, the praftical man feels diflatisfied with the manner 

 in which thofe fubje£ls are treated which come more imme- 

 tliately under his own obfervation. 



It is [ fear with fome truth that this charge is brought 

 againft that part of the arts relative to the aflaying of iron 

 ores. We never find, in the works of thofe whofe attention 

 has been dire6ted to tliis I'ubjeft, that the leaft conne£led 

 idea ever exifts betwixt the affay and the blaft-furnace, or 

 that the agents ufed for rcduilion in the laboratory can in 

 general be applied to works in the large way. A total filence 

 prevails atnongft authors of this clafs, as to the various qua- 

 lities of crude iron which certain ores and certain combina- 

 tions of fluxes produce : all ores, however various, arc re- 

 duced to the fame complex treatment, and the operation it- 

 fclf meafured by minutes, as if the fufibility of all the widely 

 diflerciitly-combined ores was the fame. 



The celebrated Bergman even, has a degree of complexity 

 in his receipts for the aflaying of iron ores, that feems un- 

 N a worthy \ 



