In the Calciners Sandy Tin Ore was spread on a round iron bed which slowly revolved over a fire so that the Ore
could be heated evenly to a dull-red heat , just below its melting point , Arsenic and Sulphur was driven off as a gas ,
the Arsenic Crystallised on the walls of a series of Labyrinths , leaving clean tin ore in the Calciner.
Ref: 4926
Date: 09/06/2017
Location: SW 3713 3481