'bocca,' through which the materials are put into the pots to melt into
glass, and by which the melted glass is taken out on the end of the
blow-pipe, or in a copper ladle, when it is to be tested by casting it.
The furnace was arched from end to end, and about the height of a tall
man; the working end was like a round oven with three glowing openings;
the straight part, some twenty feet long, contained the annealing oven
through which the finished pieces were made to move slowly, on iron
lier-pans, during many hours, till the glass had passed from extreme
heat almost to the temperature of the air. The most delicate vessels
ever produced in Murano have all been made in single furnaces, the
materials being melted, converted into glass and finally annealed, by
one fire. 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."