Discoloration of the surface of a metal due to dirt or corrosion.

Any substance that, when dissolved in water, has a sour taste, the ability to turn blue litmus red, and the ability to react with bases and certain metals to form salts.

A ring-shaped track containing freely revolving, hard metal balls against which a rotating shaft or other part turns. Ball bearings reduce friction between moving parts of a machine.

Watertight tanks on the bottom or sides of ships used to increase stability.

(BaCrO4). An anti-corrosive agent used as a yellow pigment in paints.

(C6H6) A colorless, flammable liquid derived from petroleum and used in a wide variety of chemical products, including DDT, detergents, insecticides, and motor fuels. Benzene can cause cancer.

(CdS). A yellow sulfide used chiefly as a pigment.

To check, adjust, or determine by comparison with a standard.

A chemical compound that contains CaCO3.

Any substance or agent that promotes cancer.