Something should be said of the painted Venetian glass of the seventeenth and eighteenth centuries. I say ‘painted,’ for such it is in general effect, although the pigments have probably in most cases been subjected to some kind of firing. The very poverty and dulness of the colours are indeed a proof of this; the artist’s palette has been subjected to the exigencies of the enameller’s muffle. We find landscapes with classical figures and _amorini_ painted on the lower surface of bowls and rondelles (_tondi_). In the Dutuit collection, now housed in the Petit Palais at Paris, is a circular dish some fifteen inches in diameter, painted on the under surface, so as to be viewed through the glass; the subject, a dance of cupids, is treated in an exceptionally fine style and can scarcely be later than the middle of the sixteenth century. In many cases these designs have been added to Venetian glass by non-Venetian, sometimes by northern hands. This kind of painting or enamelling is, however, very subject to injury by use, and doubtless for this reason it is sometimes protected by a second sheet of glass. We have in such painted dishes a variety of the so-called _verre églomisé_ to which reference has already more than once been made. The Venetians at times drew designs on their glass with a diamond. There are some examples of this in a good _cinquecento_ style in the Slade collection; but this work was confined to the pure scratched line, and even shading was not much used. It was not till the eighteenth century that they began to copy the later German methods of deep engraving and cutting with the wheel. The British Museum has lately acquired a square plaque of clear thick glass; at the back, in deep intaglio, is the portrait of a Doge, who, on the ground of the letters A. G. on either side of the head, may be identified with Andrea Gritti (1523-1538).[155] The late M. Piot has extracted from a fifteenth-century treatise on architecture by Antonio Averlini a dialogue between two artists upon some curious applications of glass. We hear of _cristallino_ plaques with figures carved on the lower surface, so as apparently to stand out in relief—a description which would apply well enough to this _piastra_.