2353. Ingredients for Coloring Paste to Imitate Gems

2353.    Ingredients for Coloring Paste to Imitate Gems. The following proportions must be added to 1000 parts of paste No. 12 in the above table of lead glass.

2354. For Topaz

2354.    For Topaz. Antimony glass, 40 parts; and 1 part gold purple (purple of cassius. see Nos. 2720 (To Make Purple of Cassius) to 2723.)

2355. For Ruby

2355.    For Ruby. A ruby color is given by 25 parts oxide of manganese.

2356. For Amethyst

2356.    For Amethyst. Oxide of manganese, 8 parts; 1/5 part gold purple (see Nos. 2720 (To Make Purple of Cassius) to 2723), and 5 parts oxide of cobalt.

2357. For Garnet

2357.    For Garnet. Antimony glass, 500 parts; 4 parts oxide of manganese, and 4 parts gold purple. (-See Nos. 2720 (To Make Purple of Cassius) to 2723.)

2358. For Sapphire

2358.    For Sapphire. Take 15 parts oxide of cobalt.

2359. For Aqua Marine

2359.    For Aqua Marine. Take 7 parts antimony glass, 2/5 part oxide of cobalt.

2360. For Emerald

2360.    For Emerald. Take 8 parts oxide of copper, 1/5 part oxide of chrome.

2361. To Stain or Color Glass

2361.    To Stain or Color Glass. Different colors are given to glass by the addition of metallic oxides. Thus, for amethyst, oxide of manganese is used; for blue, oxide of cobalt; for brown, oxide of iron; for green, black oxide of copper; for purple, oxide of gold; for ruby red, suboxide of copper; for white, oxide of tin; for yellow, oxide of silver, etc.. These substances are either added to the melted contents of the glass-pot, as in preparing artificial gems (see No. 2419), or are applied in a thin layer to the surface of the object, which is then heated until the coloring compound fuses as in enameling. (See No. 2378.)

2362. French Glass Used for Light-Houses

2362.    French Glass Used for Light-Houses. The special composition of the crown glass used for the light apparatus for light-houses was, until quite recently, kept a secret by the manufacturers of Saint Gobain, in France, and some firms in Birmingham, which had the monopoly of this branch of trade. From the researches of David M.

parts; dry carbonate of soda, 26i parts; lime, 4 parts; nitre, 11/2 parts; broken plate glass, 25 parts.

Henderson, C. E., we are able to furnish the composition of both. The French glass is composed of silicic acid, 72.1 parts; soda, 12.2 parts; and lime, 15.7 parts; including some traces of alumina and oxide of iron.

2363. English Light-House Glass

2363. English Light-House Glass. In Birmingham it is made from 560 pounds French sand, 203 pounds carbonate of soda, 63 pounds lime, 28 pounds nitrate of soda, and 3 pounds arsenious acid. The best qualities of this glass are at present produced in the Siemens furnace.