either absorbed into the clay or transformed by a steady blast
of air into lead oxide that evaporated, leaving the purest silver
obtainable.
At this stage, precious metals could be tested for their
purity, a necessity for the minting of coins, when the state
was guaranteeing the quality of the metal. Gold was scraped
over touchstones (black siliceous schists like basalt or chert),
leaving behind a streak whose color was compared with
those of known pure and alloyed gold. Th e Greek mathema-
tician Archimedes, of the third century b.c.e., famously dis-
covered that his body submerged in a tub displaced not its
weight but its volume in water; so by fi rst determining the
volume of a complex gold wreath made for his king, then
calculating the weight of that volume of pure gold, and fi -
nally comparing it to the actual weight of the wreath, he
could prove that the object was too light to have been made
of unadulterated gold.
Th e smelting of iron was a quite diff erent procedure,
since (unlike the ancient metallurgists of central and eastern
Asia) the Greeks and Romans were unable to attain the melt-
ing point of iron (over 2,700 degrees Fahrenheit) and so could
not produce the pure metal in liquid form. But at the man-
ageable temperature of about 2,000 degrees Fahrenheit, the
lighter slag could be separated from the iron and tapped off ,
leaving at the bottom a spongy mass called the bloom. Th is,
in turn, was repeatedly hammered to drive off the remaining
impurities and then worked into usable tools and weapons by
cold-forging or, more commonly, by annealing. Alternately
heating, hammering, and quenching the iron, which both
hardened it and combined it with carbon from the charcoal
fi re, created a form of steel.
Because of iron’s diff erent treatment from other metals,
the objects made from it were more limited in design than
tools, weapons, and decorative objects cast in bronze. Th e
smith was metallurgist and metalworker, responsible for both
smelting and working the iron in a single continuous process.
His requisite tools—tongs, hammer, and anvil—were unique
to his specialization. His work required considerable upper-
body strength, which almost certainly created the common
image of an ironworker with weak legs, a barrel chest, and
powerful arms, a caricature refl ected in the almost comical
description of Hephaistos, mythological god of the forge.
Casting, on the other hand, was the principal ancient
technique for working bronze, gold, and silver, in the Iron
Age as well as earlier. Purifi ed metal was heated to liquid
form in crucibles and poured into two-piece molds made of
stone, clay, or sand. Th e cast object could be made hollow by
inserting a removable core into the mold. Th e fi nal product
was smoothed, polished, and perhaps further decorated. One
signifi cant advantage of this technique was that the molds
were generally reusable, so multiple copies of almost identical
items could be produced with ease. As an alternative to cast-
ing, the Greeks produced sheet metal by hammering out thin
plates of metal, from which they would then “raise” cups with
a soft hammer of bone, working in a spiral from the center
and gradually thinning the metal by forcing it outward and
upward to create the sides of a round vessel.
Th e ancient Greeks practiced various techniques of fi ne
metalworking that took their creations beyond the functional
to the highly decorative. Relief work included chasing (the
hammering of a design from the outer surface) and its coun-
terpart, repoussé work (hammering from the inside to create
a raised design on the outside). Inlaying had been successfully
practiced by their Mycenaean ancestors, who produced ele-
gant ceremonial dagger blades decorated with delicate scenes
of wild animals and hunters made of gold, electrum, and sil-
ver set in an adhesive bed of black niello (a black enamel-like
alloy). Filigree and cloisonné enameling involved the use of
thin wires to create settings for precious stones, and granula-
tion was the application of tiny beads of gold to the surface
of a vessel.
An advanced form of hollow casting is known as cire-
perdue, or the “lost wax” process, which produced not just a
hollow object but one with remarkably fi ne details cast on the
surface. A rough core of destructible material was fi rst fash-
ioned, slightly smaller than the fi nished object would be, with
one or two protruding “anchors” that kept the core in place
when the next layer, the wax, was removed. A layer of liquid
wax was applied that, when hardened, was carved to the exact
design of the fi nished object. Over this was smeared a clay
shell that was attached to the “anchors” of the core, with an
unobtrusive hole giving access to the wax. Once the shell was
set, the wax was melted out of the interior, leaving a thin cav-
ity into which the molten bronze or silver was poured, taking
on both the thickness and the fi ne external decoration of the
lost wax.
When the metal cooled, the outer shell was broken (there
was no reusing of these molds) and the inner core picked
apart and removed using thin probes. Th e result was a hollow
object with a detailed surface design that could be touched up
using fi les and polishes. On a large scale this technique was
used in the casting (in multiple parts) of large bronze sculp-
tures such as the Zeus/Poseidon statue in Athens’s National
Archaeological Museum, the Charioteer of Delphi, and the
sole surviving bronze equestrian statue from antiquity, the
unparalleled Marcus Aurelius on Rome’s Capitoline Hill. Th e
achievements of the Greeks and Romans were not reproduced
until the Renaissance, when the technique of cire-perdue cast-
ing was reinvented.ROME
BY JOHN W. HUMPHREY
Th e basic facts of Greek metallurgy apply equally to the Ro-
mans, who introduced advances in only a few areas. First,
they mined the deeper copper sulfi des, which were more dif-
fi cult to smelt than the superfi cial carbonates and oxides, re-
quiring a preliminary roasting to drive off most of the sulfur
and other impurities before they could be smelted; they did,
however, increase dramatically the quantities of copper oremetallurgy: Rome 685