Abstract
All iron bacteria are characterized by the accumulation of an abundance of ferric hydrate. The oxidation of 55.8 g. of Fe as FeCO3 produces 106.8 g. of Fe(OH)3 but only 0.209 g. of organic cell material. It is difficult to establish with certainty the reactions whereby the bacteria precipitate Fe(OH)3. There are many reactions whereby Fe may be pptd. from iron-bearing waters without the participation of iron bacteria.