At least one old furnace is standing and still in use, which has existed for centuries, and those made nowadays are substantially like it in every important respect.
Zorzi stood holding a long-handled copper ladle, ready to take out a specimen of the glass containing the ingredients most lately added.

A few steps from the furnace a thick and smooth plate of iron was placed on a heavy wooden table, and upon this the liquid glass was to be poured out to cool.
"It must be time," said Beroviero, "unless the boys forgot to turn the sand-glass at one of the watches.

The hour is all but run out, and it must be the twelfth since I put in the materials." "I turned it myself, an hour after midnight," said Zorzi, "and also the next time, when it was dawn.

It runs three hours.

Judging by the time of sunrise it is running right." "Then make the trial." Beroviero stood opposite Zorzi, his face pale with heat and excitement, his fiery eyes reflecting the fierce light from the 'bocca' as he bent down to watch the copper ladle go in.