[Jewelry making - Article 00208] - Re: [Orchid] How do you melt silver coins?

[R . E . Rourke]

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    Odd, most jewelers and schools teaching metalsmithing use acetylene
    with quite satisfactory results. My own caveat being that the metal
    is prepared correctly.If not, then one sees fire scale to the point
    of blackness (= Ag2S) or sulphur and sulfides namely silver sulfide
    and hydrogen sulfide attacking and permeate the surface leaving
    tarnish and similar compounds to discolour the metal as occurs in a
    normal atmospheric reaction requiring no heat. From many years ago
    the 19th century experiments of Messrs's..M. P. E. Berthelot and L.
    J. G. Vieille made clear the reaction upon the explosion of acetylene
    and precious metals and found that if liquid acetylene was contained
    and heated to a high temperature by a platinum, or fine gold wire
    raised to a red heat, the whole mass decomposes and gives rise to
    such tremendous pressures that no cylinder can contain the mass of
    metal or the gases hovering above the metals...but that was
    contained,. You are asserting that this combining happens in an open
    atmosphere, as in general soldering. 

    I am having a hard time finding any evidence or reference that
    validates that acetylene gas "combines" with Ag in the solidus or
    liquidus states ( as it certainly does not combine in the solid
    state) even in the acid based field of coordination chemistry, or
    other fields that have no bearing on jewelery making. However there
    is much to support that silver is insoluble in gases in open
    atmospheres/ hand crafted jewelery making that is not cast with gas
    covered furnaces assisting.Gold or platinum also do not combine with
    any gases at normal or elevated temperatures. Could you give me a /
    the citation, as I would like to read about the 2 states of matter
    combining when a precious metal reaches the liquidus state, or
    approaching [those] temperatures-, say any point between flowing
    flux,solder to about 2162 C (or the boiling point of silver ) for
    instance. 

Thank you, R.E.Rourke
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