At 19:30 30/11/04 -0000, Michael Shaw wrote:
>If a reference is made to cupellation can it be assumed to be a reference to
>a production method for obtaining silver from lead or would it also include
>other similar processes for separating noble from base metals and if so what
>is the limiting factor in the process.
Mike,
Cupellation is process by which metallic lead is oxidised, absorbed by the
material forming the cupel or, in the large scale industrial process, drawn
off as litharge leaving the silver, and any gold it might contain,
unaffected. I know of no case where it means anything other than the
extraction of silver from lead. It is, however, used as the final process
in others, like the saigerprocess, where the silver contained in another
base metal is first transferred to metallic lead specifically added for
that purpose. It was also used as the final process after the Pattinson
enrichment process.
Peter
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Dr Peter Claughton,
Blaenpant Morfil, nr. Rosebush, Clynderwen, Pembrokeshire, Wales SA66 7RE.
Tel. +44 (0)1437 532578; Fax. +44 (0)1437 532921; Mobile +44 (0)7831 427599
Hon. University Fellow
School of Historical, Political and Sociological Studies (Centre for South
Western Historical Studies)
University of Exeter
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