b. Raw materials used:—
1. Yellow sand, 20%; kelp, 8%; lixiviated wood-ashes, 30%; fresh wood-ashes, 8%; pale clay, 16%; ‘cullet’ (broken glass), 18%. This is the common mixture for coarse bottles, in Belgium, France, and Germany.
2. To the last add of black oxide of manganese, 21⁄2 to 3%. Has a rich yellowish colour; used for Rhenish-wine bottles.
3. Pale sand, 51%; lixiviated wood-ashes, 33%; pearl-ashes (dried), 8%; common salt, 71⁄2%; white arsenic, 1⁄2%; charcoal, q. s. Very pale green.
4. Siliceous sand (pale), 681⁄2%; potash (or its equiv.), 4%; lime, 231⁄2%; heavy spar, 21⁄2%; peroxide of manganese, 11⁄2%. This forms the celebrated ‘flask-glass’ of St. Etienne.
Glass, Broad, Spread window glass. Sp. gr. 2·642.—
a. By analysis:—
Silica, 69·70%; lime, 13·30%; soda, 15·25%; oxide of iron (and loss), 1·75%.
b. Materials used:—
1. White sand, 50%; dried sulphate of soda, 22%; charcoal (in powder), 9%; ‘cullet,’ 41%; peroxide of manganese, a little. Pale.