Mercury is not a particularly promising homicidal poison, but it is possible to dispose of someone by feeding them mercury(II) chloride provided you disguise its metallic taste. In the 1800s solutions of corrosive sublimate, as it was then called, were used as an antiseptic and as an insecticide against bedbugs, and its very availability resulted in thousands of poisonings being reported to the health authorities, although these were mainly accidents or as a result of its being taken deliberately in order to procure an abortion. Mercury was not a poison to feature in many murder cases because it was so easily detectable by the intended victims, especially if they started to vomit, which they almost always did. Then the metallic taste became particularly noticeable, and the presence of mercury could easily be confirmed by simple analytical tests. The poisoners who chose mercury had to use a large dose and this would kill within a day or two. Despite these inherent drawbacks, a few poisoners made use of it. Two of the murderers whose cases we are about to analyse opted for the large single dose approach, but the third murderer achieved her ends by targeting her victim with multiple doses. That murder became famous because of whom she killed and the political repercussions it caused. It was also notorious for the manner in which the final fatal dose of poison was administered. Mary Bateman was known as the Yorkshire Witch and she had a plan that she thought would lead her victims into taking a fatal single dose of mercury. Instead it led her to the gallows. At the time of her crime, Bateman lived in Leeds, Yorkshire, where she earned her living telling fortunes and swindling gullible clients out of their cash and possessions. She claimed to receive her supernatural information from a spirit medium, a Miss Blythe, into whose mouth she put the advice that always seemed to result in her clients handing over their money and saleable goods, with the promise that if they did as Miss Blythe said, then good luck would soon come their way, and they would be more than compensated.