The Legacy Of Egypt

Mechanical and Technical Processes. Materials 135
are of more or less pure copper; those of the New Kingdom of
bronze. The transition seems to have occurred gradually in the
Middle Kingdom, particularly during the Twelfth Dynasty.
Native copper is very rare and the chief ancient source of supply
of copper ore seems to have been Sinai. The copper was smelted
by comparatively primitive methods, the fundamental principle
being to mix the broken ore with charcoal in a heap on the
ground or in a shallow pit, and to apply a simple form of forced
draught by means of blow-pipes (Vth Dyn.) or by bellows,
which were apparently not known until the Eighteenth Dynasty.
To give a resume of the processes of refining is outside the range
of this chapter and, indeed, much is still conjectural. Metal
was, however, both wrought and cast as early as the middle
predynastic period. Ancient Egyptian copper objects, especially
tools, show that the metal was still crystalline and that it had never
been raised to the annealing temperature. Bronze is a term used
for a mixture of copper with from 3 to 16 per cent, of tin. Its
advantages over pure copper are its hardness, its lower melting-
point, and the fact that it flows better than copper in the process
of casting. It can also be hammered cold. The source of
ancient tin is still in dispute. It may be added that brass,
an alloy of copper and zinc, is not found in Egypt until the
first century B.C.
Although known as the cOre of Heaven' from the New King-
dom iron ore does not appear to have been smelted for general
use as tools and weapons until the Twenty-fifth Dynasty. In fact
the problem of the use of iron in Egypt has formed the subject of
much controversy. The earliest definitely dated specimens of
iron are a number of small tubular beads found in a small
predynastic cemetery at El-Gerza. Although completely con-
verted into rust, chemical examination showed that they con-
tained 7j per cent, of nickel, and thus were almost certainly of
meteoric origin. The evidence of date put forward for the piece of
iron supposed to have been found in the stonework of the Great