Magnesium arsenic reduces its corrosion rate in a salt solution by a factor of nearly ten. Research showed that magnesium's tendency to creep at high-temperatures is eliminated by the addition of scandium and gadolinium. Flammability is greatly reduced by a small amount of calcium in the alloy. Magnesium forms a variety of compounds important to industry and biology, including magnesium carbonate, magnesium chloride, magnesium citrate, magnesium hydroxide (milk of magnesia), magnesium oxide, magnesium sulfate, and magnesium sulfate heptahydrate (Epsom salts). Magnesium has three stable isotopes: , and . All are present in significant amounts (see table of isotopes above). About 79%
Hydrated silica Hydrated silica Hydrated silica is a form of silicon dioxide, which has a variable amount of water in the formula. When dissolved in water it is usually known as silicic acid. It is found in nature, as opal (which has been mined as a gemstone for centuries), and in the cell walls of diatoms. It is also manufactured for use in toothpaste. Once dehydrated the gel is used as a desiccant known as silica gel. It is also used in various paints and varnishes and in the production of beer. In its pure form, as manufactured for toothpaste, it is