“What was in the letter? You opened it, of course?”
“Yes, I opened it, but the note inside was of no interest whatever. Nevertheless, I had my suspicions, and have proved them to be well grounded.”
“What have you proved?”
“Briefly this: the mark upon mademoiselle’s lip caused me to suspect poisoning; yet it was apparent that she had not attempted suicide, but that the poison, whatever its nature, had entered the tiny crack in the lip by accident. I therefore came to the conclusion that her lip had come into contact with some baneful substance immediately prior to her attack, and when you mentioned the writing of the letter it appeared to me that the gum upon the envelope might be the channel by which the poison was conveyed to the mouth. The greater part of the night I spent in dissolving the gum and making experiments with the solutions thus obtained.”
“And what did you discover?”
“I discovered the presence of a most powerful specific irritant poison. I used Mitscherlich’s method of detection, and although I cannot yet actually determine the poison with which the gum on the envelope had been impregnated, I proved its terrible effect by experiments. A rabbit inoculated with a single drop of the solution died, in fourteen seconds, of complete paralysis of the muscles, while a drop placed on a piece of meat and given to a cat proved fatal within one minute.”
“Then there was poison on the envelope?” I gasped, astounded.
“Yes, but only upon that particular envelope. While left alone in the room awaiting mademoiselle, I secured four other of the same envelopes from the stationary rack on her escritoire. These I took home at once, made solutions, and tested them upon rabbits without effect. This proved that one envelope alone was poisoned.”
“Then she was actually poisoned?” I said, surprised at his ingenuity and careful investigation.