Although most usually applied to copper-ruby glass, the flashing process is often used with other colours also. Coloured glass of this kind is at once recognised when looked at through the edges. Thus examined the glass simply shows the greenish tint of ordinary sheet-glass which constitutes practically the entire thickness of the sheet. In the same way, if such “flashed” glass be cut or etched in such a way that the layer of coloured glass is removed in places, the resulting pattern appears in white on the coloured ground--a feature which is utilised for certain decorative purposes. The flashing process just described, it should be noted, is applicable to any form of glass-ware which is blown from a gathering, and the coloured layer can be applied either upon the inside or outside of any object thus produced. In addition to the palette of colours which the glass-maker is able to supply, the artist in stained glass has a further range of colours at his disposal in the form of stains and transparent colours which can be applied to the surface of glass and developed and rendered more or less permanent by being properly “fired.” The colours produced in this way are also, in one sense, coloured glasses, or rather glazes, whose raw materials are put upon the glass by the brush of the painter, and only subsequently caused to combine and melt by suitable heating. The degree of heat applicable under these circumstances is, however, very limited by the necessity of avoiding any great softening of the substratum of glass, while many of the colours themselves are composed of materials which could not resist very high temperatures. The fluxes used in the composition of these colours must for this reason be of a very fusible kind, with the inevitable result of a greatly reduced chemical stability as compared with the glass itself.