“Ah,” he exclaimed, “black gunpowder.  Our absintheur was a bomb-maker, an expert perhaps.  Let me see.  I imagine he was making an explosive bomb, ingeniously contrived of five glass tubes.  The centre one, I venture, contained sulphuric acid and chlorate of potash separated by a close-packed wad of cotton wool.  Then the two tubes on each side probably contained the powder, and perhaps the outside tubes were filled with spirits of turpentine.  When it is placed in position, it is so arranged that the acid in the center tube is uppermost and will thus gradually soak through the cotton wool and cause great heat and an explosion by contact with the potash.  That would ignite the powder in the next tubes, and that would scatter the blazing turpentine, causing a terrific explosion and a widespread fire.  With an imperative idea of vengeance, such as that manuscript discloses, either for his own wrongs as an artist or for the fancied wrongs of the people, what may this absintheur not be planning now?  He has disappeared, but perhaps he may be more dangerous if found than if lost.”

VIII

THE MUMMY CASE

The horrible thought occurred to me that perhaps he was not alone.  I had seen Spencer’s infatuation with his attractive librarian.  The janitor of the studio-building was positive that a woman answering her description had been a visitor at the studio.  Would she be used to get at the millionaire and his treasures?  Was she herself part of the plot to victimise, perhaps kill, him?  The woman had been much of an enigma to me at first.  She was more so now.  It was barely possible that she, too, was an absintheur, who had shaken off the curse for a time only to relapse into it again.

If there were any thoughts like these passing through Kennedy’s mind he did not show it, at least not in the shape of hesitating in the course he had evidently mapped out to follow.  He said little, but hurried off from the studio in a cab up-town again to the laboratory.  A few minutes later we were speeding down to the museum.

There was not much time for Craig to work if he hoped to be ready for anything that might happen that night.  He began by winding coil after coil of copper wire about the storeroom in the basement of the museum.  It was not a very difficult matter to conceal it, so crowded was the room, or to lead the ends out through a window at the opposite side from that where the window had been broken open.

Up-stairs in the art-gallery he next installed several boxes such as those which I had seen him experimenting with during his tests of selenium on the afternoon when Mr. Spencer had first called on us.  They were camera-like boxes, about ten inches long, three inches or so wide, and four inches deep.