"Meantime, Mrs. Antrim's got her commission. She goes into the dispensary," H.M. pointed towards the half-open door across the room, "and takes down the big bromide-container: or what she thinks is the bromide container: we won't argue yet. She puts a quarter of an ounce of sodium-bromide into a half-ounce bottle. She brings it out, and hands it to Hogenauer, and he puts it in his pocket. Then Mrs. Antrim goes out — end of her testimony. For about fifteen minutes longer Hogenauer and Antrim sit talking — Antrim's testimony. Then Hogenauer says cheero, walks out of the door accompanied by the doctor, gets into his car, and is driven away. Antrim takes a stroll out on the headland to look at the sea for ten or fifteen minutes, and then returns home. Time, ten-thirty."
There was a pause. With infinite labour H.M. propelled himself up from his chair, and lumbered over to the half-open door of the surgery or dispensary. We followed him. The inner room was long but very narrow, a sort of cubicle. At the end, on the narrow side of the oblong, there was a French window giving on the rear lawn. There was an ordinary sash-window in the right-hand wall. On the two other
walls were shelves ranked with bottles, chiefly of the 10fluid-ounce size used by chemists, with wooden cupboards under the shelves. Another green-shaded lamp hung over a bench set with a tap and sink, a pair of scales, and a neat series of glass funnels.
H.M. reached up and plucked down a corked bottle on whose plain white label was printed in ink, SOD. BROM. Dose 5-30 gr.
"Ordinarily, d'ye see this kind of mix-up couldn't have happened," he went on. "Look at the other bottles. Most of 'em come from the ordinary chemical supply houses. They've got the labels worked into the glass itself, so there can't be any mistake, and they've got glass stoppers. And now take a look at this."
From the extreme end of a shelf he took down another bottle, the same size and also corked. It had a red label, on which were typed the words, STRYCHNINE FORMAS, Poison, C 21 H 22 O 2 N 2 HCOOH. Dose 1/c4 gr. Except for their labels, the two bottles looked exactly alike. The bromide bottle was half full, the strychnine bottle almost empty. Under their light their contents shone like snow.
"'For purity'," said H.M. "Look at the little jokers. Now, then. Before Hogenauer came, did somebody sneak in here with fake labels, and switch the bottles? It'd 'a' been quite easy, you know." He pointed a big flipper at the French window. "I'm authorized to say that that window's never locked, not up until the time Antrim goes to bed. And after Hogenauer had gone. why, nothin' simpler than to creep in again and change 'em back. Remember, for ten or fifteen minutes Antrim was taking a stroll along the headland. The place was open."
"But why change them back?" I asked. "It seems unnecessary fastidiousness."
"It does," agreed H.M. "Now take the alternative theory. Did somebody, in the middle of the night, creep in here when everybody was abed? Had Mrs. Antrim honest-to-God given a real bromide to Hogenauer earlier, and did the murderer come in here and arrange the trappings as Stone suggested? Take a look at that."
He nodded owlishly towards the sash-window in the right-hand wall. I was nearest it, and I did not need a magnifying-glass to see what had happened. The catch of the window had been broken, evidently by a long knife inserted from outside. On the inner sill there were some long, curious scratches.