Agatha Chistie , The Pale Horse actually saved lives on 3 occasions. The murderer used thallium sulfate, a poison that causes difficulty breathing, slurred speech, fainting spells, hair loss, and then death. In 1975, a fan was reading The Pale Horse when she recognized symptoms of thallium poisoning in her friend whose husband was slowly murdering her,She alerted authorities in the nick of time. The same book helped one other poisoning victim & help capture one serial killer.
Tetryonics 53.81 - Thallium - resembles that of the other elements in thallium's group (boron, aluminum, gallium, indium). However thallium salts (many of which are nearly tasteless) are highly toxic and have been banned in many countries, because of their non-selective toxicity. Thallium poisoning results in hair loss. Because of its historic popularity as a murder weapon, thallium has gained notoriety as "the poisoner's poison" and "inheritance powder" (alongside arsenic).
Caroline Grills, (1890 – October 1960), was an Australian serial killer. She visited her in-laws and friends, making tea, cakes and biscuits for them. After these visits many of her relatives became very ill and displayed the symptoms of thallium poisoning. A suspicious son-in-law of one of her intended victims switched tea she had made and gave it to police. It contained a lethal dose of thallium.