Page:Popular Science Monthly Volume 29.djvu/362

348 changes of fashion. New patterns bring a high price and find a ready sale till they are crowded out of the market by newer ones. For a long time the old German fashion ruled in glass, and manufacturers were obliged to use crude, impure colors, as if they were working in the childhood of art. Now, when we remember that glass-work has been regarded from a time long past as properly an effort to obtain the clearness of rock-crystal and other precious stones, it should appear that it was wrong deliberately to come down from that high ideal. The question is the one involved in the old contest of the artists with the artisans, which is still carried on with reference to the modern coal-tar colors. The former dislike these colors because they are too pronounced; the latter are inclined to regard them with more and more favor, on account of their brilliant luster, purity, and strength of color.

The author's studies of the Venetian mosaic glasses satisfied him that the harmony of the designs composed out of them was due to the subdued, broken coloring of the pieces that entered into the work, and that this was due again to the application of an impure, ferruginous sand in the melting. We must not, however, forget that glass is used in our houses, along with the precious metals, to bring out the highest lights, which even the most harmonious pictures can not dispense with. The purer, the more lustrous, and more brilliant the color of the glass, the better it answers this purpose.

The ornamentation of the glass is done partly in connection with the exposure in the furnace, and partly in the finishing-shops, where the work is completed by cutting, polishing, tarnishing, etching, painting, and mounting in metal. The glass-houses have at their command a very complete color-scale for transparent, opaque, and clouded glasses. But it must not be supposed that a crucible is placed in the furnace for each color, from which glass colored for each ornament is to be made. The colors are worked out by means of what are called pastes, which are kept on hand in sticks or cakes. From pieces of these pastes previously warmed till they are soft, suitable quantities are cut off, laid upon the foundation of white or colored glass, and then spread out by drawing or blowing. By this means only is an economical use of such costly materials as gold and silver compositions possible. Some of the glasses thus treated—gold, copper, and silver glasses—remain still little, or not at all, colored after the melting, shaping, and quick cooling; and do not take on their bright hues till they are reheated. This is the case with the new yellow-silver glass, which continues uncolored after the intermelting of the silver salt until it is exposed in the furnace again. Very fine effects are produced by blending or overrunning of the paste-colors provided proper attention is given to the laws of harmony. A blue-glass cup is, for example, overlaid with silver glass at its upper edge, and this is drawn down in gradually thinner tones till it fades away at the foot of the vase. Gold and copper ruby-colors are thus combined with green