Sturgis, after showing the damaged knife to his companion, resumed his whittling upon the cover of the box on which the artist was seated.
"Chatham's body has been dissolved in that tank within a very short time. It has entirely disappeared; this flattened bullet alone is left, lead being one of the few substances which are not soluble in the contents of that tank. Fortunately he overlooked that fact. Genius has its lapses."
Presently Sprague ventured to say:
"If numerous crimes have been committed here, as you intimate, I do not understand how it is that suspicion has never rested on this house before."
"The author of these crimes has taken every precaution to render the chance of discovery quite remote. His dwelling-house on one street, and the bogus Chemical Company on the other, are in communication through this underground passage, while apparently having no connection with each other. Moreover, he is too shrewd to make frequent use of this death chamber. That does well enough as a last resort, when he is obliged to commit the murders with his own hands; but I suspect that this man has other agents like Chatham, who do the dirty work for him and then quietly ship the bodies here for annihilation, as it was intended should be done with Arbogast's. Ah! yes; I thought so. You are sitting upon one of these bodies now."
Sprague started to his feet; and, following the direction in which Sturgis was pointing with his open knife, he vaguely discerned, through the opening which the reporter had whittled, a small surface of what had once been the features of a human being.
After gazing for some minutes in horror-stricken silence at the distorted face, the artist asked in a low voice:
"How did Chatham meet his death?"
"I don't know yet," answered Sturgis gravely; "this man is no ordinary criminal. His work is clean and leaves no blood-stains and no disorder to tell of its accomplishment. He takes life with his own hands only when he is forced to do so; but, when he does, his method is masterly. It was easier to make away with Chatham than to pay him the price agreed upon for his complicity in the Knickerbocker bank embezzlement; and so his life was taken. I hope to discover how before I leave here."
Sprague started as the reporter ceased speaking.