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GLASS may be classed into Simple and Compound varieties.
The Simple are, first, Crown Glass, consisting
of—
| Sand |
5 |
measures |
| Ground Chalk |
2 |
" |
| Carbonate of Soda |
1 |
" |
| Sulphate of Soda |
1 |
" |
Secondly, Plate Glass, consisting
of—
| Lynn Sand washed and burnt |
400 |
lbs |
| Carbonate of Soda |
250 |
" |
| Ground Chalk |
30 |
" |
Thirdly, Common Bottle Glass, composed of
| Sand |
100 |
measures |
| Soaper's Waste |
80 |
" |
| Gas Lime |
80 |
" |
| Common Clay |
5 |
" |
| Rock Salt |
3 |
" |
These Glasses, it will be observed, are
composed chiefly of silex and alkali. The Compound Glasses have, in
addition to the above ingredients, more or less metallic substances:
for instance, white enamel has arsenic, tin, or antimony, entering into
its substance, which, as well as lead, form the distinctive quality of
the Compound Glasses, materially increasing their
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