> 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.
Reading those papers again (the most detail seems to be in Charles
1980), his suggestion is that either cassiterite (SnO2) or stannite
(Cu2S.FeSSnS2) may have been added to the surface of molten Cu, via a
slag, under charcoal in the furnace to produce bronze. He discusses the
thermodynamics and goes on to say:-
"The possible use of stannite under charcoal as a surface addition ....
is interesting. There is no doubt that it will work, as practically
demonstrated by P. Stickland in cooperation with the author. Without
much practice or experience, we produced a bronze."
There is no reference and I have no further details of what was done.
I have not done this experiment myself, although I have successfully
co-smelted malachite and cassiterite, which you seem to be able to do
at any temperature above about 1000oC depending on how much grovelling
about for tiny prills you are prepared to do (and how reducing you can
get it).
I guess it would be pretty easy to repeat the Charles/Stickland
experiment if anyone is interested.
Cheers,
Paul.
Reference
Charles, J.A. (1980) The coming of copper and copper-base alloys and
iron: a metallurgical sequence. In T.A. Wertime & J.D. Muhly (eds.) The
coming of the age of iron: pp151-181. Yale: Yale University Press.
-------------------------------------------------------------------------
Dr Paul Budd
Until 31st July 2000:-
Archaeological Sciences, Uni. of Bradford, Bradford, BD7 1DP, UK
Tel: +44 (0)1274 233554, Fax: +44 (0)1274 235190
Archaeotrace
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