That makes it just slightly acidic, but still strong enough to dissolve rust if you give it enough time. Shields recommends ...

When it is exposed to air, the iron begins to rust. This rusting process produces heat ... When the pouch is broken, the water begins to dissolve the magnesium sulfate. Dissolving this type of ...

Although dissolving potassium carbonate (K 2 CO 3 ... We chose to use iron(III) oxide, or Fe 2 O 3, known more commonly as rust. We got rust off an old corrugated iron shed at the sawmill.