the art of
glazing pottery with a clear soda-lime glaze had been thoroughly
learnt. Vases, tiles, &c., shaped in good plastic clay, were covered
with a white, highly siliceous coating fit to receive glazes of this
type, and giving the best possible ground for the painted colours then
known. With this rudimentary technique the potters of the countries
south and east of the Mediterranean produced, between the 9th and 16th
centuries of our era, a type of pottery that remains ideal from the
point of view of colour: for, with nothing more than the greens given
by oxide of copper and iron, the turquoise of pure copper, the deep
yet vivid blue of cobalt, the beautiful uncertain purple of manganese,
and in certain districts the rich red of Armenian bole, they achieved
colour schemes that have never been surpassed in their brilliant yet
harmonious richness.

When the coating of white siliceous clay was replaced by an opaque
tin-enamel as in Spain, Italy, France, Holland, &c., a necessary
change in the colour schemes resulted. At first only the copper-greens
and cobalt-blues could be used on such a ground; the fine manganese
purple turned to brown or black and the rich iron-reds to filthy
shades of yellow. We cannot wonder that the Spanish-Arab potters paid
more attention to their lustre decoration, for that was the natural
thing to do. How strong and fine a palette could be evolved for use on
a tin-enamel ground was shown by the Italian majolists of the 15th and
16th centuries; and when the later developments of tin-enamelled
pottery took place in France, Holland, Germany, &c., their colour
schemes are only echoes of Italian majolica crossed with Chinese
porcelain. Delft, Nevers, Moustiers and Rouen may each charm us with
its individuality; Nuremberg and other south German towns may show us
that they too had mastered the use of tin-enamel; yet our minds always
go back to the colour schemes of Italian majolica and of the Persian
and Syrian pottery that lie behind and beyond them.

The colours already spoken of were either clay colours or what are
known as "under glaze" colours, because they were painted on the
pottery before the glaze was fired.

The earliest glazes of the Egyptians appear not to have been white,
but were coloured throughout their substance, and this use of coloured
glazes as apart from painted colour was developed along with the
painte