idea of
the general effect of these ornaments when seen in shadow against light;
an effect much calculated upon by the designer, and obtained by the use
of a golden ground formed of glass mosaic inserted in the hollows of the
marble. Each square of glass has the leaf gold upon its surface
protected by another thin film of glass above it, so that no time or
weather can affect its lustre, until the pieces of glass are bodily torn
from their setting. The smooth glazed surface of the golden ground is
washed by every shower of rain, but the marble usually darkens into an
amber color in process of time; and when the whole ornament is cast into
shadow, the golden surface, being perfectly reflective, refuses the
darkness, and shows itself in bright and burnished light behind the dark
traceries of the ornament. Where the marble has retained its perfect
whiteness, on the other hand, and is seen in sunshine, it is shown as a
snowy tracery on a golden ground; and the alternations and intermingling
of these two effects form one of the chief enchantments of Byzantine
ornamentation.

Sec. XXIX. How far the system of grounding with gold and color, universal
in St. Mark's, was carried out in the sculptures of the private palaces,
it is now impossible to say. The wrecks of them which remain, as above
noticed, show few of their ornamental sculptures in their original
position; and from those marbles which were employed in succeeding
buildings, during the Gothic period, the fragments of their mosaic
grounds would naturally rather have been removed than restored. Mosaic,
while the most secure of all decorations if carefully watched and
refastened when it loosens, may, if neglected and exposed to weather, in
process of time disappear so as to leave no vestige of its existence.
However this may have been, the assured facts are, that both the shafts
of the pillars and the facing of the old building were of veined or
variously colored marble: the capitals and sculptures were either, as
they now appear, of pure white marble, relieved upon the veined ground;
or, which is infinitely the more probable, grounded in the richer
palaces with mosaic of gold, in the inferior ones with blue color; and
only the leaves and edges of the sculpture gilded. These brighter hues
were opposed by bands of deeper color, generally alternate russet and
green, in the archivolts,--bands which still remain in the Casa Loredan
and Fondaco de' Turchi, and in a house in th