CERAMIC DECORATION—-FRANCHET. 643 
There was a reflection of this art in Spain from the thirteenth to 
the fifteenth century because the Spaniards had brought back with 
them the skill in ceramics which they had acquired in Asia. There 
the Arabs first carried out the process of applying enamel over an 
“ engobe,” a practice which persisted up to a time when the use of 
white opaque enamel had passed into the current technique. 
Again, it was the Mohammedans who brought from Persia the 
process of decoration by metallic luster, which consists in applying 
deposits of copper and silver on the enamel giving the effect of fleeting 
iridescence. This was carried from France to Spain in the four- 
teenth century and into Italy in the fifteenth. With respect to the 
latter country it would be more correct to say that the Italians went 
in search of these processes among the Moors in Spain. 
After being in disfavor for three centuries, decoration by metallic 
luster reappeared in France, at Blois first, in 1876, then on the Gulf 
of Juan-Vallauns in 1882, where it was introduced by the Italians. 
As for the pretense that the process of decoration by metallic luster 
was a secret one, I have elsewhere shown that this is not a fact 
because this process has never been completely abandoned. Some- 
times more and sometimes less of this luster pottery has been made, 
but in the last ten centuries the manufacture of it has never ceased. 
During the middle ages, when the manufacture of enameled pottery 
was at its dawn in France, the making of lining tiles occupied the 
most important place in the art. In the twelfth century they were 
content to apply a white engobe to tiles made of red clay, and then 
to cover the engobe with a glaze consisting solely of galena, a natural 
sulphide of lead, or even merely to coat them with finely divided lead, 
which oxidizing under the double influence of the heat and the oxygen 
of the air is transformed on the tile into a fusible oxide of Jead, 
making a true glass of a yellow color. 
In the thirteenth century, inlaid ceramic ware appeared to have 
been in great favor. The tile of red clay was molded in such a way 
that the design appeared in intaglio; this was filled with a white clay 
and then enameled either with the yellow lead glaze or with a green 
glaze of copper. In either case the ornamentation in white clay stood 
out clearly in tone under the glaze after firing, while the base formed 
of the red clay retained its very deep tones. 
This manufacture was kept up until the seventeenth century, mak- 
ing use principally of three colors, yellow, green, and brown, blue 
being sometimes used. 
The utilization of lining tiles for architectural decoration had 
developed to an even greater extent in Spain, where the oriental 
influence had dominated to the end of the fifteenth century—that is, 
until the Moors were driven from the Peninsula by Ferdinand the 
Fifth. 
