The single most important commercial use of lead is in the manufacture of lead-acid storage batteries (see battery, electric). It is also used in alloys such as fusible metals, antifriction metals, solder, and type metal. Shot lead is an alloy of lead, antimony, and arsenic. Lead foil is made with lead alloys. Lead is used for covering cables and as a lining for laboratory sinks, tanks, and the "chambers" in the lead-chamber process for the manufacture of sulfuric acid. It is used extensively in plumbing. Because it has excellent vibration-dampening characteristics, lead is often used to support heavy machinery and was used in the foundations of the Pan Am Building built over Grand Central Station in New York City. Lead is also employed as protective shielding against X rays and radiation from nuclear reactors.
Lead has many commonly used compounds. Commercially important are the lead oxides, which have many uses. Litharge is lead monoxide, PbO; red lead is lead tetroxide, Pb3O4; lead peroxide or dioxide, PbO2, is used in matches, as a mordant in dyeing, and as an oxidizing agent. White lead, 2PbCO3·Pb(OH)2 (basic lead carbonate), is an important pigment used in paints, putty, and ceramics. Chrome yellow, PbCrO4, is a bright yellow pigment. "Sublimed white lead," PbSO4·Pb(OH)2 (basic lead sulfate), is also used as a pigment. Lead acetate (sugar of lead) is used as a mordant, and lead azide, Pb(N3)2, is employed as a detonator for explosives. Lead arsenate is used as an insecticide. Tetraethyl lead, used as a antiknock compound in gasoline, is now banned for environmental reasons in the United States and other countries.
Although lead and most of its compounds are only slightly soluble in water, the use of lead pipe to carry drinking water is dangerous, since lead is a cumulative poison that is not excreted from the body (see lead poisoning). The "lead" of lead pencils does not contain lead; it is a mixture of graphite and clay.
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