The earliest examples of VENETIAN GLASS were massive, richly gilt and enamelled in colours; one fine example in the British museum is signed by its maker, “Magister Aldrevandini.” In the 15th and 16th centuries the most delicate and beautiful blown glass was made, often uncoloured and with enrichments of knots and wings in blown and shaped blue glass. The Venetians used with equal skill all the old methods of glassmaking; the MILLEFIORI; the LATICINIO or threads of opaque white enclosing pattern; RETICELLI, a network of white lines enclosing at the intersections a bubble of air; and the beautiful VITRO DI TRINA, filigree or lace glass, formed by canes or threads of white or coloured glass being placed in a mould, a bubble being then blown in, and the glass afterwards taken from the mould and blown or twisted to the shape required. The artistic bronze mirrors of ancient and mediæval times now give way to the glass mirrors of the Venetians, A.D. 1500. [Illustration: STAINED GLASS. Plate 31. ] STAINED GLASS with its depth and translucency, owes its intrinsic qualities to metallic oxides, such as cobalt, giving fine blues, silver, pale and deep yellows, pink from iron and antimony, and ruby from gold and copper, which also yields fine greens. When these oxides are mixed with the glass, in its fused state, it is termed _pot metal_, but if the coloured oxides are applied to the surface of the glass only, it is termed _flashed_ or _cased glass_. Ruby, owing to its depth of colour, is usually cased glass. Fine blues are often flashed, and splendid effects are produced by flashing ruby over yellow, or blue pot metal glass. Cased glass is of the greatest value owing to the variety of tint that can be produced on a single sheet of glass, and also that the colour may be removed by grinding or by the use of fluoric acid. The rationale of the glass painter is--1st, The scheme of composition and colour shown on a small scale. 2nd, A full sized cartoon in charcoal or monochrome, with all the details carefully drawn, and showing the lead lines and positions of the iron stanchions for strengthening the window. 3rd, A tracing on cloth showing the lead lines only, called the cut line, on which is cut the selected pieces of glass. 4th, Tracing all details from the cartoon, with brown enamel on each piece of glass, the pieces after firing being then fixed in the leading, and kept together with H shaped leads. A diagram is given here showing the leading of an example of 13th century glass. [Illustration] The brown enamel, which is used entirely for outline, detail or shading, is a fusible glass in combination with opaque manganic or ferric oxide, and tar oil. With this enamel, smear shading or stipple shading is worked. This may be removed as required, before firing, by means of a pointed stick or quill, so as to give the details of embroidery, or of heraldic forms.