Arsenic trioxide

Humbug Billy was sick. At his stall in the heart of Bradford, near where Kirkgate market now stands, Billy felt like he might die. Throughout the day he’d had a steady stream of customers, all eager to buy his wonderful sweets. Now Billy wondered if someone had poisoned them.

The year was 1858 and the Bradford Sweets Poisonings had begun. By the end, some 200 people would fall ill, with 21 deaths. And it was all because of daft.