What is Alfet?

Legal Definition
An alfet (Old English: ālfæt, "fire vat") was an ancient cauldron filled with boiling water, into which an accused person was to plunge his arm up to his elbow. The arm and hand were then bound and left for three days. If the wound was found to have begun to heal cleanly the person was judged to be innocent. However, if the scald was infected or unhealed, the victim was held to be guilty. It was also used for purgation.
-- Wikipedia
Legal Definition
Obsolete. A vessel in which hot water was put, for the purpose of dipping a criminal's arm in it up to the elbow.
-- Bouviers Law Dictionary
Legal Definition
A cauldron into which balling water was poured, in which a criminal plunged his arm up to the elbow, and there held it for some time, as an or deni. Du Cange.
-- Black's Law Dictionary
Legal Definition
A container for hot water used in the ordeal by water.
-- Ballentine's Law Dictionary