_a._ Composition by analysis:--
1. Silica, 53·55%; lime, 29·22%; mixed alkali, 5·48%; alumina, 6·01%;
oxide of iron, 5·74%. Dark green.
2. Silica, 52%; baryta, 21·6%; soda, 26·1%; oxides of iron and manganese,
·3%. Pale green; very superior.
_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, 2-1/2 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, 7-1/2%; white arsenic, 1/2%; charcoal, q. s. Very pale green.
4. Siliceous sand (pale), 68-1/2%; potash (or its equiv.), 4%; lime,
23-1/2%; heavy spar, 2-1/2%; peroxide of manganese, 1-1/2%. This forms the
celebrated 'flask-glass' of St. Etienne.