It wasn't until 1752 that the first true test case for the emergent science
made its appearance in a European court of law. At the trial of the poisoner
Mary Blandy, expert witness Dr Anthony Addington was asked how he could prove
that a packet of white powder found at the defendant's home was arsenic. He
replied that it was of the same consistency and texture as arsenic and that it
had produced thick white plumes of vapour when placed on a red-hot iron just as
arsenic would do.
Confessions were extracted by torture at the hands of the Spanish Inquisition
(c 1500)
The fact that the crime occurred in a remote rural region meant that the
police could safely assume that the culprit was a local man and so had only to
eliminate the innocent from a small number of suspect to identify the guilty
party.