its vitreous state.

Enamel has been used from very early times. The first allusion to
it is by Philostratus, in the year 200 A. D., where he described
the process as applied to the armour of his day. "The barbarians
of the regions of the ocean," he writes, "are skilled in fusing
colours on heated brass, which become as hard as stone, and render
the ornament thus produced durable."

Enamels have special characteristics in different periods: in the late
tenth century, of Byzantium and Germany; in the eleventh century, of
Italy; while most of the later work owes its leading characteristics
to the French, although it continued to be produced in the other
countries.

It helps one to understand the differences and similarities in
enamelled work, to observe the three general forms in which it is
employed; these are, the cloisonne, the champleve, and the painted
enamel. There are many subdivisions of these classifications, but
for our purpose these three will suffice.

In cloisonne, the only manner known to the Greek, Anglo-Saxon, and
Celtic craftsmen, the pattern is made upon a gold ground, by little
upright wire lines, like filigree, the enamel is fused into all the
little compartments thus formed, each bit being one clear colour,
on the principle of a mosaic. The colours were always rather clear
and crude, but are the more sincere and decorative on this account,
the worker recognizing frankly the limitation of the material; and
the gold outline harmonizes the whole, as it does in any form of
art work. A cloisonne enamel is practically a mosaic, in which the
separations consist of narrow bands of metal instead of plaster.
The enamel was applied in its powdered state on the gold, and then
fused all together in the furnace.

[Illustration: GERMAN ENAMEL, 13TH CENTURY]

Champleve enamel has somewhat the same effect as the cloisonne,
but the end is attained by different means. The outline is left in
metal, and the whole background is cut away and sunk, thus making
the hollow chambers for the vitreous paste, in one piece, instead of
by means of wires. Often it is not easy to determine which method
has been employed to produce a given work.

Painted enamels were not employed in the earliest times, but came
to perfection in the Renaissance. A translucent enamel prevailed
especially in Italy: a low relief was made with the graver on gold
or silver; fine raised lines were left here and there, to separate
the colours. Theref