Page:Popular Science Monthly Volume 37.djvu/187

This page has been proofread, but needs to be validated.
175
GLASS-MAKING.

lieved that the vase was made of onyx, and described it as a most interesting cameo. It is now known to be made of glass composed of two layers.

The Portland vase was a hint to the glass-makers, and one that they made good use of. In the most elaborate examples of the modern product three colors are employed, and the effect, if the material has been judiciously managed, is exceedingly beautiful.

A vase is the best type of the cameo glass, since the function of the ware is almost wholly decorative. From beginning to end the process is one of great ingenuity. The basis of the vase is commonly of opalescent glass—that is, glass made opaque by the presence of some finely ground but insoluble oxide, or some such mineral as cryolite or fluor-spar. A lump of this glass is gathered on the end of the blowpipe and formed into a symmetrical shape by rolling on the marvering-table. It is then dipped at short intervals into two baths of molten glass of the colors desired. The composite lump is fashioned into shape by means of those various manipulations which the glass-blowers perform so adroitly. This gives a vase made up of three distinct layers of different colors. Its subsequent treatment is both chemical and mechanical. The design is painted on the glass by hand, or else transferred with special care from freshly printed paper, as in the case of the etched globes. The vase is then dipped into the bath of hydrofluoric acid and allowed to remain until both of the outer colors on the exposed portions are eaten off. It is now taken out, the ink washed off, and its subsequent treatment intrusted to the engraver. At this stage of the process only two out of the three colors are plainly visible, the intermediate one being seen simply as a colored line between the other two surfaces. By means of the engraving-wheel the outline of the design is made more clear cut, and enough of the outer layer removed to show the intermediate color as a delicate shading. An immense amount of work can thus be put upon a comparatively small article, and the cost meanwhile grows in proportion. Single pieces have been manufactured in England valued as high as two thousand dollars.

In spite of its great beauty and ingenuity, however, it is an undeniable fact that the cameo glass is losing rather than gaining in favor with the buying public. Some of the establishments which formerly produced it have ceased to do so. Several causes have been assigned for this lessened appreciation. Manufacturers say that the cost has been so far reduced that the rich will not buy it, and, in consequence, the middle classes no longer care for it. But such is not the general course of events in industrial matters, and the statement is to be taken with a grain of salt. The probable trouble is, that some of the cameo-ware has been