Up: Glassmaking
How It Is Made
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making of glass, will probably be unable to give the narrative much
credit.
There are three kinds of glass in common use, all
containing-- (1) sand (silica), as the acid element; (2) soda or potash,
as the alkaline "base"; (3) lime or oxide of lead, as the alkaline earth.
FLINT-GLASS
--made of sand, 100 parts; red lead, 70 parts; potassium carbonate, 33 parts--
is employed mainly for the manufacture of tumblers and other tableware, and
for ornamental objects. It has a naturally brilliant surface, which is
improved by cutting and polishing on grindstones and emery wheels. The
presence of the lead renders it fusible at a comparatively low temperature,
and so particularly suitable for the manufacture of pressed goods.
CROWN-GLASS
--sand, 100 parts; carbonate of soda, 33 parts; lime, 15 parts; cullet, or
glass scrap, 100 parts-- is used for plate or window glass.
BOTTLE-GLASS
For common bottle-glass the materials generally
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