As she passed through the lobby she paused at the telegraph desk a moment, then went into the writing room.
"Yes, I think I have an explanation," began Haynes, when she was out of sight. "I've been trying to figure out what could have killed Delaney. Of course I can only guess, but I don't think it is such a bad guess."
"What is it?" asked Craig.
"You remember the mercury vapor light?"
Kennedy nodded.
"Mercury vapor lights of that sort are a pretty good source of ultra-violet rays sometimes," went on Haynes. "Well, doubtless you know that various plants belonging to different families produce free prussic acid. They are really cyanogenetic plants. Light and the assimilation processes depending on light exert a favorable influence on cyanogenesis. For instance, a mixture of citric acid with a much smaller amount of potassium nitrite and a trace of bicarbonate of iron, if exposed to light, will generate hydrocyanic acid. That, I believe, is what actually happens in some plant tissues. Animals rarely touch such plants. I believe that such a process might be aided rather than retarded by ultra-violet rays. What do you think of it?"
Craig was following Dr. Haynes keenly. As for me, I was astounded by his frankness. I recalled what Kennedy had already said up in Delaney's apartment, and watched his face covertly.
"Your explanation is plausible," was all that Craig said. "By the way, have you found out anything about the Baroness?"
"Not a word, yet," replied Haynes unhesitatingly. "She seems to be out of town."
"And madame—has she any idea where she is?"