This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
These were formerly much more used than at present; and were not dismissed from our Pharmacopoeia until the late revision. As kept in the shops, they are too often the mere refuse of the workshops, and are consequently impure, not unfrequently containing particles of copper and other metals. Obtained from this source, they should be pounded and sifted; and may then be, in some degree, further purified by drawing them through a sieve with a magnet, which attracts the iron, leaving the isolated particles of other metals, and at the same time the coarser particles of the iron itself. This method, however, answers but imperfectly; and the only method of securing them, fit for medical use, is to prepare them directly by filing, from a piece of pure soft iron. The present French Codex (ad. 1866) directs them to be prepared from iron by means of a file of steel, and then beaten so as to obtain a coarse powder, with the grains always uniform. They should be kept quite dry, in well-stopped bottles, to prevent oxidation, and should have a bright and clean appearance.
I have no doubt that iron filings, or steel-dust as they were often called in old times, are an efficient chalybeate. The flatulence they may occasion is but a trifling inconvenience, while their mildness, and facility of entrance into the system through the action of the gastric acids, are positive recommendations. The great objection to them is their frequent impurity. They have, however, at present, been entirely superseded by the reduced powder of iron which has all their advantages, in a still higher degree, without their disadvantages.
The dose of iron filings is from five to fifteen grains. They may betaken in powder with syrup, or in the form of pill.
Porphyrized iron is a preparation directed by the French Codex. and is made by rubbing pure iron filings into the state of impalpable powder, by means of porphyry. Its colour is black, probably owing to a partial oxidation. The dose is the same as that of the preceding preparation, or somewhat less.