Cooley's Cyclopædia of Practical Receipts and Collateral Information in the Arts, Manufactures, Professions, and Trades..., Sixth Edition, Volume I

by Arnold James Cooley; Richard Vine Tuson

b. Materials used:—

1. Purest quartz, 42%; red lead (finest), 42%; purified potash, 14³⁄₄%; purified nitre, 1¹⁄₄%. These are the proportions used for the last.

2. (Korner.) Finest quartz (reduced to powder, treated with hydrochloric acid, washed, and dried), 47¹⁄₂%; red lead, 38¹⁄₄%; cream of

tartar, 14¹⁄₂%. The above are used by opticians in the construction of achromatic object-glasses.

Glass, Plate. Sp. gr. 2·488 to 2·600.—

a. By analysis:—

1. (Dumas.) Silica, 75·9%; soda, 17·5%; lime, 3·8%; alumina, 2·8%. French mirror-glass.

2. (Mitscherlich.) Silica, 60%; potassa, 25%; lime, 12·5%; loss, 2·5%(?). Finest Bohemian plate.

b. Materials used:—

1. Finest siliceous sand, 45%; dried carbonate of soda, 25%; lime, 5%; nitre (purified), 2%; plate-glass cullet, 23%; peroxide of manganese and cobalt azure, a very little. Ordinary English plate.