Moist Ferric Hydrate

Synonyms.—Moist Ferric Hydrate Ferri Peroxidum Hydratum Moist Hydrated Peroxide of Iron. 

If, in place of bringing two solutions in contact with each other, they be separated by a solid or semi-solid, moist, colloid layer, diffusion takes place in the same way through the interposed layer. Advantage is taken of this fact to separate crystalloids from colloids by the process of dialysis. The mixed solutions of ciystalloid and colloid are brought into the inner vessel of a dialyser. Fig. 13, whose bottom consists of a layer of moist parchment paper, while the outer vessel is filled with pure water. "Water passes into the inner vessel, and the crystalloid passes into the water in the outer vessel. By frequently changing the water in the outer vessel, solutions of the albuminoids or of ferric hydrate, etc., almost entirely free from crystalloids, may be obtained. 

When exposed to moist air iron becomes oxidized, forming a loose coating of rust, which is a partially hydrated ferric oxide. 

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