Herr von Czihak mentions that he has seen in the museum of Freiberg, in Saxony, a covered _humpen, painted in oil-colours_, protected apparently with some kind of lacquer. The glass is dark green, and the Gothic character both of the metal cover and of the painting points to a date not later than 1500. The subject, according to a quaint inscription, has relation to ‘_Eneaspius der Babst_’ (the Pope Pius II., 1458-1464), and to the ‘_Roemischer Kaiser Friderich der dritt_’ (_Schlesische Gläser_, p. 101). Footnote 203: What Mathesius states is, ‘The white [_i.e._ colourless] glasses have now become common over which white threads of white colour are carried; these glasses are made in Silesia.’ Herr von Czihak (p. 96) says that he has seen many such glasses of somewhat rude make in that province. It will be remembered that some of the _vetro di trina_ made at Murano is also only superficially decorated. Footnote 204: On the other hand, the technique of the cemetery glasses differs essentially, as in these the two plates of glass are fused together, on the edges at least (p. 92). Footnote 205: We often find similar defects developed on glass lenses. To ensure achromatism and accuracy of definition these lenses are built up of two layers, one of crown, the other of flint glass, cemented together by a varnish. Footnote 206: This art was carried to the highest perfection in Holland by a group of cultured amateurs in the seventeenth century (see p. 295). Footnote 207: We hear, it is true, of water-wheels for grinding glass at Schwäbisch Grund, in Bavaria, in the second half of the sixteenth century. In these mills large beads (perhaps we may think of the chevron beads from Murano in this connection) were ground for exportation to the Indies by way of Antwerp (Von Czihak, p. 125). I may note that there is no reference to the cutting of glass in either Agricola or Mathesius. Footnote 208: It is interesting to compare with this work the carving—identical in technique—on reliquaries of rock crystal of Carlovingian date. Of these a remarkable example may be seen in the Mediæval Room in the British Museum. Footnote 209: The Schatzkammer at Munich is rich in examples of carved rock crystal of this period, but I can find few examples of carved glass in it. In the Imperial Museum in Vienna may be seen a superb series carved in both materials—the finest of these come from the Schatzkammer. Footnote 210: Lehmann died in 1622, and the elder George Schwanhart in 1667. Footnote 211: Compare with this the complaints, made at this time or a little later, of the artistic and social decadence of the glass-engravers in Bohemia and Silesia (p. 285). Footnote 212: On the early use of hydrofluoric acid I shall have something to say a little further on. Footnote 213: