From: A History of Technology (Oxford-Clarendon Press) vol. 4 page 138: "A
further process patented by Alexander Parkes of Birmingham in 1850 was based
on the observation that when zinc and lead are melted together and allowed to
cool, any silver present becomes concentrated in the zinc. The method used in
1851 was to add 22.4 lb of zinc for every 14 oz silver in each ton of lead to
be treated. On cooling the melt, the zinc-silver crystals that rose to the
surface were drawn out in a perforated ladle. Lead and zinc were removed by
heating to dull redness in air, skimming, and then removing the remaining
zinc by acid or distillation.......almost complete separation of the silver
was effected."
From: Nathaniel Arbiter [log in to unmask]
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