A Pinch of Poison by Frances Lockridge

detective’s hands. Weigand’s fingers closed, just in time, on departing hindquarters. Andy was rearranged.
    â€œHold his head up a little,” Francis directed. Weigand got a finger under the cat’s chin and lifted.
    â€œNow,” Francis said. “I’ll put one drop of the serum in his right eye. Watch.”
    Francis, while Andy glared darkly at him, held the dropper over the cat’s face. A drop came out. It hit the cat’s nose, thanks to Andy’s quick movement. Francis steadied the cat’s head and dropped again. The second drop went into the right eye. Andy jumped under Weigand’s hands, which this time were ready. Andy yowled.
    â€œWatch the eye,” Francis directed. Weigand watched. For a moment nothing happened. Then the pupil began to widen. The pupil of the left eye remained contracted against the light. Francis switched it off.
    â€œNo reason to blind the beast,” he said. “You saw how they were. Now look at the right one.”
    The pupil of the right eye, now, was almost fully dilated. Even with the flood light off, the pupil of the left eye had dilated only a little. Andy looked oddly lopsided.
    â€œO.K.,” Francis said. “There’s your test.” He lifted Andy and put him back in his cage. “All right, boy,” he told the cat. “It’ll wear off after a while.” He turned to Weigand.
    â€œThere you are,” he said. “It was atropine, all right. There was enough atropine in the blood to dilate a cat’s eyes—and enough to kill a girl. Probably administered in the form of atropine sulphate. Which dissolves in almost anything.”
    Weigand nodded.
    â€œGood enough,” he said. “Tell me about atropine sulphate.”
    Dr. Francis told him. Atropine sulphate was a drug used in medicine—in ophthalmology, for example; internally to check secretions; sometimes in cases of surgical shock to stimulate respiration and circulation. It acted by stimulating the higher nerve centers, while at the same time paralyzing the peripheral endings of the nerves of the autonomic system.
    â€œWell, well,” Weigand said. “Think of that. What does it look like?”
    â€œIt’s a powder,” Dr. Francis told him. “A white powder. No odor. No strong taste. At least, that’s what they say. I never tasted it myself. The dose is very small, normally from one-two-hundredth to one-one-hundredth of a grain. A grain ought to kill a couple of people.”
    â€œHow quickly?” Weigand wanted to know. Francis lifted his shoulders. It depended on the dose. Since it wasn’t a custom to give lethal doses of atropine sulphate to humans, the data was incomplete. But from a few minutes to a couple of hours, depending on the size of dose, and other conditions.
    â€œI’d say your subject got quite a dose,” he added. “Probably about a grain.”
    It wasn’t satisfactory, Weigand decided. Lois might have got the poison before she left home; she might have got it at the restaurant table shortly before she collapsed. But that wasn’t, obviously, Dr. Francis’ fault.
    â€œHow would you get it?” he asked. “I mean, just walk into a drugstore and say, ‘I’d like some atropine sulphate, please. About enough to kill a guy!’”
    â€œWell,” Francis said, “ I’d requisition it. But—no, I don’t suppose you could get it at a retail store.” He thought it over.
    â€œI’ll tell you,” he said. “You could go to a drug supply house and say you were a manufacturer and wanted some atropine sulphate. If you looked all right, or went to the trouble of having letterheads printed or something, they’d sell it to you. There’s no law against it.”
    â€œWhat would I be manufacturing?” Weigand wanted to know.
    â€œWhat?” said Francis. “Oh—eyewash, of course. It’s used, in minute