“Nothing in the shape of any foreign compound?  You once showed me a Turkish liquid that burnt when water was poured on it, and dyed everything blood red.”

“Ah, yes, the fozeska, something truly dangerous.  But I know of nothing—­ But hold!” The doctor clapped his hands together.  “Yes! yes!  That would do it, that and that only.”

“What?”

“I had a sample of it given to me some six months ago.  It was called yamlang-peholo, and was made in China, from the roots of the yamlang bush—­a rare growth found only in the western part of the country.  By many Chinamen the yamlang bush is supposed to be accursed, and whenever they come near one they utter a prayer for deliverance from its evils.  If you sleep near the yamlang bush it will make you very sick.”

“And that powder, what did it look like?”

“It was blue at first but on contact with the air quickly changed to brownish-white and lost itself, it was so fine.”

“Evaporated?”

“You can call it that if you wish.  It was intense.  I held it at arms’ length, yet it made me sick and I had cramps for over an hour afterwards.”

“It would have killed you if you had placed it to your mouth or nose?”

“Not the slightest doubt of it.”

“May I ask where you got the stuff?”

“It was imported into this country by a drug firm merely as a curiosity.  They put it up in tiny vials which I suppose were sent around to different persons like myself.  It was a dangerous piece of business and I gave them no credit for doing it.”

“What was the name of the firm?”

“I would not tell everybody, but I know I can trust you to keep a secret.  The firm was Alexander & Company, of Rochester, who stand very high in the trade.  I buy many things from them, from time to time, and their traveling man, a Mr. Ostrello, gave me the powder when he called.  He told me how the firm had experimented on a dog and an ox.  Both died in less than two minutes, and each with cramps.  But after death neither animal showed the least trace of the poison.”

“Wasn’t this Ostrello afraid to handle the stuff?”

“Not as much as I was.  He said he was a bit used to it.  I told him I didn’t want to get used to it.  Have another glass of wine?”

“No, I prefer to smoke, thanks just the same.  I am interested in this yamlang, as you call it.  Where can I get the stuff?”

“No more of it can be had.  I rather think they got afraid of it.  Wait, I’ll get the vial it was in.  Perhaps there is a whiff left in it.”

“Thanks, but do you think I want to die?” queried the detective, and gave a laugh.

When the empty vial was produced he opened it and took a short sniff.  Then he drew his breath in sharply.  A faint odor was perceptible, the same odor he had detected in the carpet on the upper hallway of the Langmore mansion.