Chemistry Reference
In-Depth Information
fact and its composition, as reflected in their analyses (see Table 47); all the
ornaments, for example, which are made of arsenical copper, were finished
off to close tolerances, whereas the tools, all made of unalloyed copper, were
left rough. This may be so either because the tools are older, or made by dif-
ferent crafters than the ornaments.
The high toxicity of arsenic may have been what led, at a later stage, to
the gradual discontinuation of the use of arsenic in copper metallurgy. It is
now known, however, that toxicity had little influence on the choice of tech-
nological processes in early times. An interesting sidelight on arsenical
copper technology is the fact that arsenical copper ores were not of common
occurrence in the old world. The only known deposits of importance then
known seem to have been in Armenia. This would suggest that the supply
routes along which the raw materials could be brought from Armenia to the
Mediterranean Sea area were already established as far back as Chalcolithic
and early Bronze Age times.
Damascus Steel
Damascus steel
, also known in the Western world as
Damascene steel
, is a
special type of steel that was and is still used to make sward and knifeblades.
Apparently, Damascus steel was first made in India, where it was known as
wootz
or
kuft
, and later (during the second century B.C.E.) it was developed
in Persia. The name “Damascus steel” was used by the Crusaders to describe
the steel used by sword smiths of Damascus, Syria, famous for their ability
to hammer and temper the steel into fine blades. The sword blades made
from the steel had a reputation for their exceptional properties, especially
their toughness, the retention of their cutting edge, as well as for a particu-
lar and characteristic decorative pattern on their surface (Figiel 1991).
Metallographic and chemical studies have shown that the toughness of
Damascus steel is due to a very high carbon content of the steel, while the
retention of the cutting edge resulted from variations in the distribution of
the carbon within the steel blade. Damascus steel blades also had a charac-
teristic decorative, much appreciated pattern that was produced by a con-
trolled process of etching the surface with an appropriate acid solution: the
acid selectively dissolved iron from the surface layer, creating the decorative
pattern (Wadsworth and Sherby 1980; Voss 1976). It has been suggested that
some Damascus steel blades may have been made exclusively from steel
smelted from selected ores, and that impurities in the ores, passed on to the
metal during smelting, may have caused the formation of the characteristic
etch patterns on the finished blades (Verhoeven et al. 1998; Verhoeven and
Peterson 1992).
