"Are you sure Marietta came here?" asked Beroviero, growing paler.

"Quite sure. They were on their way here together early in the morning
when I stopped them, and asked Marietta where she was going, and she
boldly said she was going to see Zorzi. I could not prevent her, and I
saw them both go in."

"Do you mean to say that although Zorzi was so badly hurt you did not
have him brought to the house?"

"Of course I proposed that at once," Giovanni answered. "But he said
that he would not leave the furnace."

"That was like him," said old Beroviero.

"He knew what he was doing. It was on that same day that a night boy
told me how he had seen you and Zorzi burying something in the
laboratory the night before you left."

Beroviero started and leaned forward. Giovanni smiled thoughtfully, for
he saw how his father was moved, and he knew that the strongest part of
his story was yet untold.

"It would have been better to leave Paolo Godi's manuscript with me," he
said, in a tone of sympathy. "I grew anxious for its safety as soon as I
knew that Zorzi had charge of it. Yesterday morning I came in again.
Zorzi was sitting on the working-stool, finishing a beautiful beaker of
white glass."

"White glass?" repeated Beroviero in evident surprise. "White glass?
Here?"

"Yes," answered Giovanni, enjoying his triumph. "I pointed out that when
I had last come, there had been no white glass in the furnace. He
answered that as one of the experiments had produced a beautiful red
colour which he thought must be valuable, he had removed the crucible.
He also showed me a specimen of it."

"Is it here?" asked Beroviero anxiously. "Where is it?"

Giovanni took the specimen from the table, for Zorzi had left it lying
there, and he handed it to his father. The latter took it, held it up to
the light, and uttered an exclamation of astonishment and anger.

"There is only one way of making that," he said, without hesitation.

"Yes," Giovanni answered coolly. "I supposed it was made according to
one of your secrets."

A quick look was the only reply to this speech. Giovanni continued.

"I asked him to sell me the piece of glass he had been making when he
came in, and at first he pretended that he was not sure whether you
would allow it, but at last he took a piece of gold for it, and I was to
have it as soon as it was annealed. When you see it, you will understand
why I was so anxious to get it."

"Where is it?" asked the old ma