The host bowed.

"The fumes, whatever they were, killed swiftly?"

"They did. Instantly; mercifully. Too mercifully."

"How could you know it was fumes?" demanded Mr. Thomas Colvin
McIntyre.

"By the dead flies, the effect upon the bell-boy, and the fact that
no wound was found on the body. Then, too, there was the fulminate
of mercury shell."

"Of what possible use was that?" asked Professor Gehren.

"A question that I've asked myself, sir, a great many times over in
the last twenty-four hours. Perhaps Mr. Smith could answer that
best. Though--er--I think the shell was blown through the blowpipe
to clear the deadly fumes from the room by its explosion, before any
one else should suffer. Smith is, at least, not a wanton
slaughterer."

"You are right, sir, and I thank you," said the foreigner. He drew
himself up weakly but with pride. "Gentlemen, I am not a murderer.
I am an avenger. It would have gone hard with my conscience had any
innocent person met death through me. As for that Turkish dog, you
shall judge for yourself whether he did not die too easily."

From among the papers in a tiroir against the wall he took a French