Dear John,
They are both correct! The first referred to the the lowest
theoretical temperature that could be used according to the Ellingham
diagram, which is about the same as that of iron. As with iron, higher
temperatures were normally used in most periods and certainly for the
Industrial Revolution under discussion by Professor Tylecote the higher
temperature was used. The slag found at the Bronze Age site of
Caerloggas in Cornwall shows that similarly high temperatures were
being used by 1500BC. The need for higher temperatures are usually the
need to speed up the reactions, or to facilitate the separation of the
metal from the gangue elements - usually done by the formation of a
slag. Most slags require temperatures in the 1100-1200 C range to become
sufficiently liquid to perform this function.
Chris
Hillman wrote:
> Two authoritative sources offer quite different temperatures at which
> tin metal is released from its oxide
>
> 700 degrees C :
> J. G. McDonnell, "Pyrotechnology," in D. R. Brothwell and A. M. Pollard,
> eds., Handbook of Archaeological Sciences (Chichester: Wiley, 2001), p.
> 499.
>
> 1100 degrees C
> R. F. Tylecote, The industrial revolution in metals Institute of
> Metals, 1991.p 37
>
> Can these be reconciled or is one wrong ?
>
> John Hillman
>
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