Also, he caught a pungent odor, which he recognized, and which reminded him of the conversation he had heard just before he plunged through the broken banister.
“Ammonia, as sure as I am here,” he muttered. “I’ll have to move quickly, for it seems to me as if the stuff has been disturbed lately. If it has, probably it means——”
The thump of an engine made him pause.
“The fiends! They are generating the ammonia gas, and, of course, they will set it free by opening some of the valves, and then——”
The smell of ammonia waxed stronger, and his breath began to come with difficulty.
He fumbled along the rough stone wall, damp with the ooze of the marsh, until he came to an iron tank, from which the fumes were emerging so strongly that he reeled away, half suffocated.
“This won’t do. They’ll get me like a stray dog in a gas chamber if I don’t find my way out.”
The thumping of the engine continued, and his sense of direction told him that it was against the wall in which was a heavy door.
“There is a pump and it works underneath the tank in some way,” muttered Nick. “I can’t get at it on this side. The only chance would be to get to the other room, and the door is too heavy to be broken down in a hurry. I have no tools, and——”
“Gee! That’s a bum smell!”