"And do you really believe that there is much secret poisoning in London at this moment?" I inquired, greatly interested. "Believe it?" he echoed. "Why, there's no doubt of it. Why do people buy certain herbs which can be used for no other purpose than the destruction of human life?" "Do they actually buy poisons openly?" I exclaimed in surprise. "Well, no, not exactly openly," he responded. "They are most of them very wary how they approach the subject, and all are prepared to pay heavily." I looked at the odd, ugly figure before me. For the first time I had learned the secret of this trade. Perhaps even he retailed poisons to those who wanted such undesirable commodities, charging exorbitant prices for them, and entering fictitious sales in the poison-book which, by law, he was compelled to keep. "Have you actually ever had dealings with any poisoners?" I inquired. "Remember," I added laughing, "that I'm not interviewing you, that we are friends, and that I don't intend to publish this conversation in the newspapers." "That's rather a difficult question," he responded, with a look of mystery upon his face. "Perhaps I'd best reply that I've before now sold poisons to people who could want them for no other purpose than the removal of superfluous friends." "But do they actually ask openly for this herb or that?" "Certainly--with excuses for its use, of course," and he went on to remark how lucidly the science of poisoning was explained in a certain book which might be purchased anywhere for seven-and-sixpence, a work which had undoubtedly cost thousands of human lives. Then instantly I recollected. It was a copy of this same book that Dick had noticed in the morning-room at Riverdene. "In this very room," the old fellow went on, "I've had some queer inquiries made by all sorts and conditions of people. Only the other day a young girl called to consult me, having heard, she said, that I sold for a consideration a certain deadly herb. By her voice she was evidently a lady." His final observation increased my interest in this remarkable conversation. "What was she like?" I inquired with eagerness, for since the affair at Phillimore Place I took the keenest interest in anything appertaining to poisons. "She was rather tall and slim, dressed in black. But my eyes are not so good as they used to be, and, in the dark here, I couldn't see much of her face through her veil. She was pretty, I think." "And did you actually sell her what she wanted?" He hesitated a moment.