"Now let me try—shut the door, Sault, that is right." Steppe got out of the chair to spin the dials. "Now we will suppose that I am some unauthorized person trying to find a way of opening the safe. So!"
He turned the handle.
"Open it."
Sault worked at the dials and presently the door swung open. The newspapers were saturated and an inch of water at the bottom of the safe splashed out and into a bath-tub that Sault had put ready.
"How about cutting into the safe? Suppose I am a burglar, huh? I burn out the lock or the side, and don't touch the combination?"
"I have left a hole in one side of the safe," said Sault, and pointed to a rubber plug that had been rammed into a small aperture.
With a pair of pincers he pulled this out and a stream of water spurted forth and was mostly caught in the can he held.
"That has the same effect," he explained. "The water is pumped at a pressure into the hollow walls of the safe. The door is also hollow. When the water runs out, a float drops and releases the contents of the upper chamber. In the case of the door, the float operates the same spring that floods the safe when the handle is turned."
Steppe scratched his head. "Perfect," he said. "You have experimented with the acid?"
Sault nodded. "Both with sulphuric and hydrochloric," he said. "I think hydrochloric is the better."