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Thanks Nathaniel, One last point, how did the miners know there was any silver present in the lead, or did the lead smelting process show this? ----- Original Message ----- From: <[log in to unmask]> To: <[log in to unmask]> Sent: Saturday, April 29, 2000 11:04 PM Subject: Re: Silver from lead > 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] > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%