I put him back, conscious at his touch of a certain icy pang along my blood. "Come, sir," said I. "You forget that I have not yet the pleasure of your acquaintance. Be seated, if you please." And I showed him an example, and sat down myself in my customary seat and with as fair an imitation of my ordinary manner to a patient as the lateness of the hour, the nature of my pre-occupations, and the horror I had of my visitor, would suffer me to muster. "I beg your pardon, Dr. Lanyon," he replied civilly enough. "What you say is very well founded; and my impatience has shown its heels to my politeness. I come here at the instance of your colleague, Dr. Henry Jekyll, on a piece of business of some moment; and I understood ..." he paused and put his hand to his throat, and I could see, in spite of his collected manner, that he was wrestling against the approaches of the hysteria--"I understood, a drawer...." But here I took pity on my visitor's suspense, and some perhaps on my own growing curiosity. "There it is, sir," said I, pointing to the drawer, where it lay on the floor behind a table and still covered with the sheet. He sprang to it, and then paused, and laid his hand upon his heart; I could hear his teeth grate with the convulsive action of his jaws; and his face was so ghastly to see that I grew alarmed both for his life and reason. "Compose yourself," said I. He turned a dreadful smile to me, and as if with the decision of despair, plucked away the sheet. At sight of the contents he uttered one loud sob of such immense relief that I sat petrified. And the next moment, in a voice that was already fairly well under control, "Have you a graduated glass?" he asked. I rose from my place with something of an effort and gave him what he asked. He thanked me with a smiling nod, measured out a few minims of the red tincture and added one of the powders. The mixture, which was at first of a reddish hue, began, in proportion as the crystals melted, to brighten in colour, to effervesce audibly, and to throw off small fumes of vapour. Suddenly and at the same moment, the ebullition ceased and the compound changed to a dark purple, which faded again more slowly to a watery green. My visitor, who had watched these metamorphoses with a keen eye, smiled, set down the glass upon the table, and then turned and looked upon me with an air of scrutiny.