would give to clay the polish and the hardness of marble. After many trials, a varnish made of tin (_étain_), which was white, opaque, and of a resisting nature, furnished him with the result he hoped for. The art of producing fine earthenware was discovered, which first received the name of vitrified clay (_terra invetriata_). “Luca’s enamel was a most perfect white; he first used it alone for figures, in semi-relief, which were raised on a blue background. At a later period he ventured to colour his figures, and Pietro di Medici was one of the first who encouraged this kind of work for the decoration of palaces. The fame of this novel art spread with rapidity; all the churches were anxious to possess some specimen of the master, so that Luca was soon compelled to associate with himself his two brothers Ottaviano and Agostino, in order to keep pace with the requirements of the public. He endeavoured, nevertheless, to extend the application of his discovery by painting flowers and groups of figures on a smooth surface; but in the year 1430 death cut short his remarkable career, and stayed, in the hands of the inventor, the progress of _enamelled pottery_ (Fig. 35). [Illustration: Fig. 35.--Enamelled Terra-cotta, by Luca della Robbia.] “The family of Luca, however, made public the secret of his discovery. His two nephews, Luca and Andrea, produced some figures and designs of singular merit in terra-cotta. Luca ornamented the floor of the Loggia of Raphael. Girolumo, a relative of Luca, come to France, where he decorated the château of Madrid, in the neighbourhood of Paris. Two females, Lisabetta and Speranza, added to the renown of the family Della Robbia.” Such is the history of the revival, or rather of the creation, of ceramic art in Italy, as briefly recorded by a man thoroughly acquainted with the subject. An ancient author, and, moreover, a competent writer, instances some monuments of an earlier date; among others a tomb at Bologna, in which were tiles covered with a green and yellow varnish, and vessels (_écuelles_) of the same kind inserted in the façades or porticoes of the churches of Pesaro and the abbey of Pomposa. But to the honour of Luca della Robbia it may be remarked, that these specimens of an earlier industry differed essentially from his productions; because the glazing that covered them, the basis of which was lead, was so transparent, that through it could be seen either the clay or the colours underneath; whereas the enamel discovered by Luca, the basis of which was tin, had, on the contrary, for its essential character, an opacity which may be termed intense. Let us observe, moreover, that in order to embellish his productions with paintings, Luca was accustomed to apply colours to the first and general coating, which became fixed by a subsequent process of baking.