[27] The pale rosy tint seen in a few rare specimens of classical glass, as in some pieces lately brought from Egypt, I should rather attribute to a skilful use of manganese.
[28] The presence of tin in this glass which I have already mentioned in speaking of its Egyptian prototype (p. [27]), has been confirmed by analyses made at Sèvres by M. Salvétat. I do not know whether the researches of this chemist into the composition of the glass of the ancients have ever been published.
[29] In the Roman floor mosaics the tesseræ are almost invariably of stone, but occasionally fragments of glass are found, as in the famous ‘Mosaic of the Philosophers’ in the museum at Cologne. Here the ground is built up of a smeltz-like greenish glass.
[30] We may compare this use of glass with the kyanos studs of the Mycenæan period, or again with the blue glass inlaid between the volutes of the capitals in the temple of Minerva Polias at Athens, described long ago by Hamilton.
[31] In the glass coffin from the Temple collection in the British Museum we have an example of the use of such glass on a comparatively large scale.
[32] Mr. Kennard has a plaque of clear white glass, some six inches in length, with the bust of a faun in high relief. This plaque is pierced on either side, as if for fixing upon some object of furniture.
[33] We may regard the little ovoid vase in the British Museum, made by blowing a thin vesicle of deep blue glass into a casing of silver, pierced by oval apertures, as an example of moulded glass where the mould has not been removed. If the silver casing were stripped off, we should have a good imitation of ‘prunted’ glass; not that this is to be taken as a model of the way in which these prunts were made (see below, p. [110]).
[34] How far the so-called diatretum work is based upon such appliqué or added portions of glass is a much disputed point. Mr. Nesbitt appears to have regarded all such work as so formed (Catalogue, Slade Collection, pp. xiv.-xv.), and the imitations now made at Murano are certainly built up in this way; not so, however, some of the genuine ancient pieces, I think. (See below, p. [71].)
[35] The Egyptians, too, as we have seen, sometimes decorated their glass with similar splashes, but we never find that these are distorted.
[36] There are many allusions to the painting of glass, in some cases merely by varnishes, in the early mediæval treatises on glass (see [Chap. VII.]). Some of these recipes, as we shall see, may have been handed down from classical times.