The chlorination process in gold extraction employs large vats or revolving barrels, the material inside of which is moistened with water and treated with chlorine gas to form a solution of Gold Chloride. This is then run off, and the gold precipitated , usually by means of Ferrous Sulphate or charcoal.
John H. Finley ed. Nelson's Perpetual Loose-Leaf Encyclopaedia (vol. 5) (New York, NY: Thomas Nelson and Sons, 1917) 479