In Medieval times, the lash was often used as one of the many implements of persecution or suppression.  At various times during these eras, many different groups or beliefs were targeted.  One such group were those practitioners of Alchemy.  It is easy to imagine the scene above:  This man, a long time dabbler in the arts of fire and brimstone is arrested and sentenced.  He is taken to a damp, smelly, rat-infested dungeon.  Under the night-marish, flickering light of torches, he is whipped... and branded... and racked.... 
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