The coruscations of colour died away, the spiral threads of fire had spent themselves, the liquid had disappeared, and at the bottom of the glass was a small sediment, which Dr. Pye carefully emptied into a piece of white satin tissue paper, which he carefully folded and put into his pocket. Then he spoke. "I gave the maid instructions that no person was to be admitted to see me, as I was engaged upon an exceedingly delicate experiment which it has taken me some days to prepare." "I hope it has been successful," I said, politely. "I cannot tell," he answered. "The small modicum of powder I have collected is in its present state valueless except as a destroyer." "As a destroyer?" "Yes. The minutest portion of it dissolved in a glass of water is sudden death. But these are matters in which you cannot be expected to take an interest." "Pardon me, doctor. To all men of intelligence such matters are of the deepest interest"--I was proceeding when he waved the subject away. "It is not of my scientific experiments you have come to speak. I see by your card"--he referred to it--"that you are a detective officer." "My name is tolerably well known," I said, and he stopped me again. "To members of the criminal classes, no doubt. I am behind the age, I am afraid." If he thought to mortify me by implying that he had never heard of me he did not succeed. "It is known to others outside those classes. You have read my evidence in the case?" "In what case?" "The Catchpole Square case." "No," he said, "such cases have no attraction for me. I used to take in the daily newspapers, but I found that they distracted my attention from my pursuits, so now I read only scientific papers." "But you gave evidence at the inquest, doctor!" "I know I did. A friend mentioned the matter to me, spoke of incidents connected with it, and said that the murder must have taken place on the night of Friday, the 1st of March. I recollected that I was up late that night, and that, as I stood at my window at three in the morning, some unusual movement in the Square forced itself upon my attention; I recollected that I had used an insignificant little invention of mine, a new kind of flash-light, to ascertain precisely the details of the movement. I spoke of this to my friend, who said it was my duty to come forward and relate what had come under my observation. In consequence of that remark I tendered my evidence, and was glad to be rid of the affair." "But you are not rid of it, doctor," I said. "How is that?" "Have you not heard that Mr. Reginald Boyd has been arrested for the murder?" "No, I have not seen a newspaper this week, and you are the first visitor I have had. The young man has been arrested, has he? I trust he will be able to clear himself. When did the arrest take place?" "Yesterday evening. I made it. It is news to you, then, that he was brought before the magistrate this morning?" "Yes, it is quite new to me. What was the result?"