To all who have, so far, commented to my query regarding adding cassiterite
to molten copper to produce a bronze (10% Sn):
I believe Charles suggested in a paper with the delightful title "Arsenic and
Old Bronze" that bronze could be made using a cap of a mixture of cassiterite
and charcoal situated above the molten Cu thus effecting a reduction of the
Sn that then dripped into the Cu; but I do not recall his conducting any
experiments. This method, however, begs the query since the cassiterite is
not added directly to the Cu. I know of no experiments in France or elsewhere
and would be most appreciative if someone (Noel Gale et al) could point me in
the right direction.
I assume that during the Bronze Age, the systems were open systems. They
could have had a covering of charcoal constituting a "closed system".
I will await an answer from those at Bradford who may have done these
experiments.
My query may be a moot one since it is (in my view) unlikely that cassiterite
would have been shipped during the Bronze Age the great distances (dealing
here only with the ancient Near East) as cassiterite and not the so much
easier transportable smelted Sn metal. As far as we know today, the source of
the Sn is not known but may have come from as far away as eastern Iran or
western Afghanistan. It is likely, then, that the Sn would have been added
directly to the Cu. The situation, however, for the Bronze Age in Britain
does make the query less moot.
Another point from which a deduction may be drawn is that to the best of my
knowledge no cassiterite as stable as it is has been found in connection with
a bronze making facility in the ancient Near East. No Sn also has been found
but this can be explained by other means (the beta to alpha transformation).
But, as you all know, discovery of Sn ingots has become almost constant in
these days from Bronze Age contexts (Ulu Burun shipwreck, Israeli ingots,
etc).
R. Maddin
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