Up: Glassmaking
Reminiscences
15 of 123
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Another singular property of glass is shown in
the fact, that when the furnace, as the workmen term it, is settled, the
metal is perfectly plain and clear; but if by accident the metal
becomes too cool to work, and the furnace heat required to be raised,
the glass, which had before remained in the open pots perfectly calm
and plain, immediately becomes agitated or boiling. The glass rises in
a mass of spongy matter and bubbles, and is rendered worthless. A change
is however immediately effected by throwing a tumbler of water upon the
metal, when the agitation immediately ceases, and the glass assumes its
original quiet and clearness.
All writers upon the subject of glass manufacture
fail to show anything decisive upon the precise period of its invention.
Some suppose it to have been invented before the flood. Nervi
traces its antiquity to the yet problematical time of
Job.
It seems clear, however, that the art was known
to the Egyptians thirty-five hundred years since; for records handed down
to us in the form of paintings, hieroglyphics, &c., demonstrate its
existence in the reign of the first Osirtasen,
and existing relics in glass, taken from the ruins of
Thebes, with hieroglyphical data, clearly
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