Hitherto he had failed in every attempt.

He had tried one mixture after another, and had produced a score of different specimens, but not one of them had that marvellous light in it, like sunshine striking through bright blood, which he was striving to obtain.

It was nearly three weeks since his small furnace had been allowed to go out, and by this time he alone knew what the glowing pots contained, for he wrote down very carefully what he did and in characters which he believed no one could understand but himself.
As usual every morning, he proceeded to make trial of the materials fused in the night.

The furnace, though not large, held three crucibles, before each of which was the opening, still called by the Italian name '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.