But what was this cold wind which had sprung into life at the very outset of the chant? The lamps were sputtering woefully, and the gloom grew so dense that the letters on the wall nearly faded from sight. There was smoke, too, and an acrid odour which quite drowned out the stench from the far-away wells; an odour like that he had smelt before, yet infinitely stronger and more pungent. He turned from the inscriptions to face the room with its bizarre contents, and saw that the Kylix on the floor, in which the ominous efflorescent powder had lain, was giving forth a cloud of thick, greenish-black vapour of surprising volume and opacity. That powder—Great God! it had come from the shelf of "Materia"—what was it doing now, and what had started it? The formula he had been chanting—the first of the pair—Dragon's Head, ascending node—Blessed Saviour, could it be. . . .