Dexterously he proceeded to seal up every crack in the safe door with the soap, leaving a small gap at the top unsealed. Then round that gap he built what was to all intents and purposes a soap dam.
"If any of you boys," he remarked to the intent group around him, "think of taking this up as a means of livelihood, be careful of this stuff." From another pocket he produced an india-rubber bottle. "Don't drop it on the floor if you want to be measured for your coffin. There'll just be a boot and some bits to bury."
The group faded away, and the American laughed.
"Might I ask what it is?" murmured Hugh politely from the neighbourhood of the door.
"Sure thing, Captain," returned the detective, carefully pouring some of the liquid into the soap dam. "This is what I told you I'd got—gelignite; or, as the boys call it, the oil. It runs right round the cracks of the door inside the soap." He added a little more, and carefully replaced the stopper in the bottle. "Now a detonator and a bit of fuse, and I guess we'll leave the room."
"It reminds one of those dreadful barbarians the Sappers, trying to blow up things," remarked Toby, stepping with some agility into the garden; and a moment or two later the American joined them.
"It may be necessary to do it again," he announced, and as he spoke the sound of a dull explosion came from inside the house. "On the other hand," he continued, going back into the room and quietly pulling the safe door open, "it may not. There's your book, Captain."