face to face. The door we will leave ajar. Each is now in a position to watch the other and to bring the experiment to an end should the symptoms seem alarming. Is that all clear? Well, then, I take our powder—or what remains of it—from the envelope, and I lay it above the burning lamp. So! Now, Watson, let us sit down and await developments.”
They were not long in coming. I had hardly settled in my chair before I was conscious of a thick, musky odour, subtle and nauseous. At the very first whiff of it my brain and my imagination were beyond all control. A thick, black cloud swirled before my eyes, and my mind told me that in this cloud, unseen as yet, but about to spring out upon my appalled senses, lurked all that was vaguely horrible, all that was monstrous and inconceivably wicked in the universe. Vague shapes swirled and swam amid the dark cloudbank, each a menace and a warning of something coming, the advent of some unspeakable dweller upon the threshold, whose very shadow would blast my soul. A freezing horror took possession of me. I felt that my hair was rising, that my eyes were protruding, that my mouth was opened, and my tongue like leather. The turmoil within my brain was such that something must surely snap. I tried to scream, and was vaguely aware of some hoarse croak which was my own voice, but distant and detached from my-
