"No trouble, sir. At what time shall I be back?"

Dorian looked at Campbell. "How long will your experiment take, Alan?" he said in a calm indifferent voice. The presence of a third person in the room seemed to give him extraordinary courage.

Campbell frowned and bit his lip. "It will take about five hours," he answered.

"It will be time enough, then, if you are back at half-past seven, Francis. Or stay: just leave my things out for dressing. You can have the evening to yourself. I am not dining at home, so I shall not want you."

"Thank you, sir," said the man, leaving the room.

"Now, Alan, there is not a moment to be lost. How heavy this chest is! I'll take it for you.