The iron chair was used as punishment. Crimes that are punishable by the iron chair include adultery, witchcraft, murder, etc. The instrument was used until the late 1800s in Europe.The iron chair was a torture device that was added to dungeons in the middle ages.The iron chair has many different variations depending on its location but they consisted of 500-1500 spikes covering the whole chair with a hole on the seat for fire and coal to be placed under.