Bower-barff process

[Sarah]

A certain process for producing upon articles of iron or steelan adherent coating of the magnetic oxide of iron (which is notliable to corrosion by air, moisture, or ordinary acids). This isaccomplished by producing, by oxidation at about 1600º F. in a closedspace, a coating containing more or less of the ferric oxide (Fe2O3)and the subsequent change of this in a reduced atmosphere to themagnetic oxide (Fe2O4).