“Then take no steps until I tell you.  Shadow Mrs. Morowitch and Mr. Kahan, but do not let them know you suspect them of anything.  Let me run down this Poissan clue.  In other words, leave the case entirely in my hands in other respects.  Let me know any new facts you may unearth, and some time to-morrow I shall call on you, and we will determine what the next step is to be.  Good night.  I want to thank you for putting me in the way of this case.  I think we shall all be surprised at the outcome.”

It was late the following afternoon before I saw Kennedy again.  He was in his laboratory winding two strands of platinum wire carefully about a piece of porcelain and smearing on it some peculiar black glassy granular substance that came in a sort of pencil, like a stick of sealing-wax.  I noticed that he was very particular to keep the two wires exactly the same distance from each other throughout the entire length of the piece of porcelain, but I said nothing to distract his attention, though a thousand questions about the progress of the case were at my tongue’s end.

Instead I watched him intently.  The black substance formed a sort of bridge connecting and covering the wires.  When he had finished he said:  “Now you can ask me your questions, while I heat and anneal this little contrivance.  I see you are bursting with curiosity.”

“Well, did you see Poissan?” I asked.

Kennedy continued to heat the wire-covered porcelain.  “I did, and he is going to give me a demonstration of his discovery to-night.”

“His discovery!”

“You remember Morowitch’s ‘hallucination,’ as the doctor called it?  That was no hallucination; that was a reality.  This man Poissan says he has discovered a way to make diamonds artificially out of pure carbon in an electric furnace.  Morowitch, I believe, was to buy his secret.  His dream of millions was a reality—­at least to him.”

“And did Kahan and Mrs. Morowitch know it?” I asked quickly.

“I don’t know yet,” replied Craig, finishing the annealing.

The black glassy substance was now a dull grey.

“What’s that stuff you were putting on the wire?” I asked.

“Oh, just a by-product made in the manufacture of sulphuric acid,” answered Kennedy airily, adding, as if to change the subject:  “I want you to go with me to-night.  I told Poissan I was a professor in the university and that I would bring one of our younger trustees, the son of the banker, T. Pierpont Spencer, who might put some capital into his scheme.  Now, Jameson, while I’m finishing up my work here, run over to the apartment and get my automatic revolver.  I may need it to-night.  I have communicated with Andrews, and he will be ready.  The demonstration will take place at half-past-eight at Poissan’s laboratory.  I tried to get him to give it here, but he absolutely refused.”

Half an hour later I rejoined Craig at his laboratory, and we rode down to the Great Eastern Life Building.