81. Thallium

81 Tl Thallium 204.383 A Perfect Murder Agatha Christie knew she'd been poisoned as soon as the symptoms began to show. Give her that much credit, at least! Hair loss, lethargy, tingling of the hands and feet, slurred speech … It was thallium poisoning. Thallium mimicked potassium, an essential element, which made it particularly difficult to get rid of. The body would excrete it into the intestines where, insidiously enough, it would be mistaken for potassium and reabsorbed. There was no known cure. Agatha knew, too, who the murderer was. Subtract ten days from the onset of hair loss, and one arrived at a literary luncheon. One accepted a cup of tea from a writer of international renown who was nevertheless jealous of her sales. Oh yes, Ernest was the culprit, all right. But that wasn't important now. Agatha needed to find a cure, and quickly. If there was no known cure, she would simply have to find an unknown one. Oddly enough, this was not her first brush with thallium poisoning. As a child, several classmates had come down with it—and one had died—after drinking milk from a cow that had eaten molasses baits laced with thallium sulfate and laid out for the rats. Seven children had drunk the milk, yet only six had fallen ill. One had not. What was his name? Gummy! Gummy Oglethorpe. The other children had called him Gummy because … Agatha lurched to her writing desk and snatched up the bottle of blue ink. Spasmodically, she drank it down. The next day she was a little better, and the day after better yet. She kept drinking ink until the symptoms were entirely gone. Gummy Oglethorpe had been a compulsive fountain pen sucker. It had turned his gums the most amazing blue. Clearly something in the ink—she suspected the Prussian Blue—had substituted potassium for thallium, allowing the latter to be flushed from his system. Now that she was better, Agatha turned her attention to her would-be murderer. Bloody amateur. She needed a way to kill him that would be swift, sure, and so perfectly undetectable that she would never be suspected of the deed. She found it, of course. Give her that much credit, at least! © 2003 by Michael Swanwick and SCIFI.COM.