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specific gravity, and acting a powerful fluxes. The Compound Glasses
are as follow—viz.,
FLINT GLASS.
Highly pellucid and transparent Flint Glass
requires—
| Carbonate of Potash |
| 1 |
cwt. |
| Red Lead or Litharge |
2 |
cwt. |
| Sand washed and burnt |
3 |
cwt. |
| Saltpetre |
14 |
lbs. to 28 lbs. |
| Oxide of Manganese |
4 |
oz. to 12 oz. |
These materials, mixed together, are
technically called batch; and when fused, are termed metal.
Soft White Enamel (Opaque.)—To
6 cwt. of batch, add 24 lbs. of arsenic, 6 lbs. of antimony.
Hard White Enamel (Opaque.)—To
6 cwt. of batch, as above, add 200 lbs. of putty, prepared from tin and
lead.
Blue Transparent Glass.—The
above 6 cwt. of batch, coloured with 2 lbs. of oxide of cobalt.
Azure Blue.—The
above 6 cwt. of batch, with about 6 lbs. of oxide of copper.
Ruby Red.—The
above 6 cwt. of batch, with about 4 oz. of oxide of gold.
Amethyst or Purple.—The
above 6 cwt. of batch, with about 20 lbs. of oxide of manganese.
Common Orange.—To
6 cwt. of batch, add 12 lbs. of iron ore, and 4 lbs. of manganese.
Emerald Green.—To
6 cwt. of batch, add 12 lbs. of copper scales, and 12 lbs. of iron ore.
Gold Topaz Colour.—The above
6 cwt. of batch with 3 lbs. of oxide of uranium.
A beautiful blue may be produced from nickle,
but cobalt is generally preferred; the latter, for casing, should be
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