For as long as there have been targets that needed to be removed quietly, there have been poisoners. For centuries, poison has often been the favored tool for political assassinations in a number of societies. The Romans and Persians were both said to have had special children who were slowly fed increasing doses of a lethal poison. Eventually, the child would exhibit the desired side effects of being immune to the poison and being so saturated with it that even their sweat or saliva was poisonous. There are many naturally occurring poisons, with hemlock and nightshade being examples, but more civilized poisoners have one chemical of preference. That chemical is arsenic.
Arsenic poisoning is often a slow, time-consuming process that leads to an equally slow, painful death. Arsenic poisoning is, according to one serial poisoner who fancied herself a philosopher, an art form and a precise science. Controlled doses, preferably starting with small amounts that increase over time, are ideal to avoid the body’s drug metabolism from rejecting it. Too strong a dose and the body simply forces the poison out with minimal side effects, which was what happened to Napoleon...