<P> Filings are mostly a byproduct of the grinding, filing, or milling of finished iron products, so their history largely tracks the development of iron . For the most part, they have been a waste product . </P> <P> Iron filings have some utility as a component in primitive gunpowder . In such a fine powdered form, iron can burn, due to its increased surface area . </P> <P> The primary utility of iron filings is in the study and teaching of magnetism and electromagnetic fields . The substance makes impressive demonstrations when sprinkled on a white card placed on top of a permanent magnet, such as a bar magnet . The filings can be found in toys that allow one to draw with a magnetic pen . By sprinkling fine iron on a magnetic stripe card, it is possible to see the magnetic encoding on the stripe . A semi-viscous fluid in which iron filings are suspended, may be poured onto the exposed platter of a hard drive, so that the patterns of bits on the platter are revealed by the alignment of the iron filings . </P> <P> Iron filings are also used to fortify enriched foods for human consumption . However, it is known that pure iron in its metallic form is not processable by the human body, it would usually be excreted . In the acidic environment of the stomach iron will be oxidized, producing an equivalent amount of hydrogen . </P>

Are the iron filings in the test tube magnetized which end is the north and which is the south