34 8 THE POPULAR SCIENCE MONTHLY. 



quent 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 manufact- 

 urers were obliged to use crude, impure colors, as if they were work- 

 ing 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, paint- 

 ing, 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 atten- 

 tion is given to the laws of harmony. A blue-glass cup is, for exam- 

 ple, 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 



