before--she has been poisoned with _iodine_, which, administered in certain quantities, would produce precisely the same symptoms. Happily there is no mode of destroying human life which so surely leads to the detection of the murderer as the use of such agents; and of this truth the post mortem examination of the body, which takes place to-morrow morning, will, if I am not grossly mistaken, supply another vivid illustration. Legal assistance will no doubt be necessary, and I am sure I do not err in expecting that _you_ will aid me in bringing to justice the murderer of Mary Rawdon?" A pressure of his hand was my only answer. "I shall call for you at ten o'clock" said he, as he put me down at my own door. I bowed, and the carriage drove off. "Well!" said I, as Dr. Curteis and Mr. ---- the eminent surgeon entered the library at Mount Place the following morning after a long absence. "As I anticipated," replied the doctor with a choking voice: "she has been poisoned!" I started to my feet. "And the murderer?" "Our suspicions still point to young Bourdon; but the persons of both mother and son have been secured." "Apart?" "Yes; and I have despatched a servant to request the presence of a neighbor--a county magistrate. I expect him momently." After a brief consultation, we all three directed our steps to the summer-house which contained young Bourdon's laboratory. In the room itself nothing of importance was discovered; but in an enclosed recess, which we broke open, we found a curiously-fashioned glass bottle half full of iodine. "This is it!" said Mr. ----; "and in a powdered state too--just ready for mixing with brandy or any other available dissolvent." The powder had somewhat the appearance of fine black lead. Nothing further of any consequence being observed, we returned to the house, where the magistrate had already arrived. Alfred Bourdon was first brought in; and he having been duly cautioned that he was not obliged to answer any question, and that what he did say would be taken down, and, if necessary, used against him, I proposed the following questions:-- "Have you the key of your laboratory?" "No; the door is always open." "Well, then, of any door or cupboard in the room?" At this question his face flushed purple: he stammered, "There is no"--and abruptly paused. "Do I understand you to say there is no cupboard or place of concealment in the room?" "No: here is the key." "Has any one had access to the cupboard or recess of which this is the key, except yourself?" The young man shook as if smitten with ague: his lips chattered, but no articulate sound escaped them. "You need not answer the question," said the magistrate, "unless you choose to do so. I again warn you that all you say will, if necessary, be used against you." "No one," he at length gasped, mastering his hesitation by a strong exertion of the will--"no one can have had access to the place but myself. I have never parted with the key."