Many attempts have been made to color with ruby or other colors gas shades, so as to throw on surrounding objects the color of the glass; but in no case has the ray of light passing through colored glass, to refract the shade, been successful.
But when a ray of solar light is passed through a colorless prism, it is refracted, and forms, when thrown on a wall or screen, a broad band of colored light,--red, orange, yellow, green, blue, indigo, and violet,--which is known as the prismatic or solar spectrum.
We find a report in French journals that M. Gannal has succeeded in obtaining _crystals_, having all the property of the diamond, through the mutual reaction of phosphorus water and bisulphide of carbon upon each other for the space of fifteen weeks.
The crystals were found to be so hard that no file would act upon them. They cut glass like ordinary diamonds, and scratched the hardest steel. In brilliancy and transparency they were in no way inferior to the best jewels, and some possessed a lustre surpassing that of most real stones.
For reference we record the cost of materials for flint-glass, say in 1840 to 1845, as follows:--
Litherage, or red lead, cost 6-1/2 cts. per lb. Pearlash, 6 " " Nitre, 6 " " Silex, 0-1/2 " "
Red lead, 21 cts. per lb. Pearlash, 17 " " Nitre, 6 " " Silex, 0-3/4 " "
We now refer to the early introduction of the manufacture of glass into England. The English manufacturers, like ourselves, had to struggle with the various evils incident to the introduction of a new art. France and Germany, from their long experience in the making of glass, were enabled for a long time to undersell the English manufacturer in his own market.
To foster and protect this branch of national industry, the English government imposed a heavy tax on all foreign glass imported into their dominions. This measure secured to the English manufacturer the entire trade, both with their colonies and with the home market, thus giving such substantial encouragement to the enterprise, that, in a few years, the manufacture was so much increased as to admit of exportation.
To stimulate the exportation of various articles of English production, the government, in the latter part of the eighteenth century, granted bounties, from time to time, on linens, printed cottons, glass, &c, &c. Until the bounty on glass was allowed, the exportation of glass from England to foreign countries was very limited; for the French and Germans, as has before been stated, for various reasons could undersell the English; but the government bounty changed the aspect of affairs, and shortly the English manufacturers not only competed with the Germans and French for the foreign market, but actually excluded them from any participation,--the government bounty being equal to one half the actual cost of the glass exported.