Hydrated Peroxide of Iron. Ferri Sesquioxydum Hydratum. Hydrated Sesquioxide of Iron (2 Fe2O3, 3 HO) with a variable amount of uncombined water. Prep. Made by precipitating a solution of Persulphate of Iron with Soda. The precipitate is to be collected on a calico filter, and washed with distilled water until the filtrate ceases to give a precipitate with Chloride of Barium. It is to be preserved, without drying, in a well-covered vessel. The preparation should be recently made.

Med. Uses. As an antidote for poisoning by Arsenic, this preparation was first proposed by Bunsen and Berthold, in 1884. It converts Arsenious Acid into an Arseniate of Iron which is insoluble (2 Fe2O3 + As O3 = 4 FeO + AsO5). It has been extensively tried; and, although some instances are recorded in which it failed to produce any good effect, it is, without doubt, one of the best antidotes we possess. Of thirty-one cases quoted by Dr. Beck,§ recovery took place in twenty-nine. It appears, however, that it is more a mechanical than a chemical antidote. It is stated that thirty-two parts of the Peroxide are required for every part of the arsenic swallowed. It should be given in a moist state, in doses of a tablespoonful, every five or ten minutes, oroftener. Should the Hydrated Sesquioxide not be at hand, the common Sesquioxide may be substituted.