The door opened suddenly and Giovanni entered.  Zorzi turned and looked at him in silence.  He was surprised, but he supposed that the master’s son had a right to come if he chose, though he never showed himself in the glass-house when his father was in Murano.

“Are you alone here?” asked Giovanni, looking about him.  “Do none of the workmen come here?”

“The master has left me in charge of his work,” answered Zorzi.  “I need no help.”

Giovanni seated himself in his father’s chair and looked at the table before the window.

“It is not very hard work, I fancy,” he observed, crossing one leg over the other and pulling up his black hose to make it fit his lean calf better.

Zorzi suspected at once that he had come in search of information, and paused before answering.

“The work needs careful attention,” he said at last.

“Most glass-work does,” observed Giovanni, with a harsh little laugh.  “Are you very attentive, then?  Do you remember to do all that my father told you?”

“The master only left this morning.  So far, I have obeyed his orders.”

“I do not understand how a man who is not a glass-blower can know enough to be left alone in charge of a furnace,” said Giovanni, looking at Zorzi’s profile.

This time Zorzi was silent.  He did not think it necessary to tell how much he knew.

“I suppose my father knows what he is about,” continued Giovanni, in a tone of disapproval.

Zorzi thought so too, and no reply seemed necessary.  He stood still, looking out of the window, and wishing that his visitor would go away.  But Giovanni had no such intention.

“What are you making?” he asked presently.

“A certain kind of glass,” Zorzi answered.

“A new colour?”

“A certain colour.  That is all I can tell you.”

“You can tell me what colour it is,” said Giovanni.  “Why are you so secret?  Even if my father had ordered you to be silent with me about his work, which I do not believe, you would not be betraying anything by telling me that.  What colour is he trying to make?”

“I am to say nothing about it, not even to you.  I obey my orders.”

Giovanni was a glass-maker himself.  He rose with an air of annoyance and crossed the laboratory to the jar in which the broken glass was kept, took out a piece and held it up against the light.  Zorzi had made a movement as if to hinder him, but he realised at once that he could not lay hands on his master’s son.  Giovanni laughed contemptuously and threw the fragment back into the jar.

“Is that all?  I can do better than that myself!” he said, and he sat down again in the big chair.

His eyes fell on the shelves upon which Zorzi’s specimens of work were arranged.  He looked at them with interest, at once understanding their commercial value.

“My father can make good things when he is not wasting time over discoveries,” he remarked, and rising again he went nearer and began to examine the little objects.