Building insulation materials weak and brittle. Before its risks were recognized, it was used because it was a cheap, effective insulator with a high R-value and its open-cell structure was a good acoustic insulator. Though it absorbed moisture easily, it regained effectiveness as an insulator when dried. Asbestos once found common use as an insulation material in homes and buildings because it is fireproof, a good thermal and electrical insulator, and resistant to chemical attack and wear. It has been found that asbestos can cause cancer when in friable form (that is, when likely to release fibers into the air - when broken,
Magnesium and carbon: Hence, carbon dioxide fuels rather than extinguishes magnesium fires. Burning magnesium can be quenched by using a Class D dry chemical fire extinguisher, or by covering the fire with sand or magnesium foundry flux to remove its air source. Magnesium compounds, primarily magnesium oxide (MgO), are used as a refractory material in furnace linings for producing iron, steel, nonferrous metals, glass, and cement. Magnesium oxide and other magnesium compounds are also used in the agricultural, chemical, and construction industries. Magnesium oxide from calcination is used as an electrical insulator in fire-resistant cables. Magnesium reacted with an alkyl halide