Lead was one of the earliest metals discovered by the human race and was in use by 3000 B.C. The ancient Romans used lead for making water pipes and lining baths, and the plumber who joins and mends pipes takes his name from the Latin word plumbum, meaning lead. Plumbum is also the origin of the terms plumb bob and plumb line, used in surveying and also the chemical symbol for lead, Pb. In medieval times, lead came to be used for roofing, coffins, cisterns, tanks, and gutters, and for statues and ornaments. Another early use of lead was for the strips joining the pieces of colored glass in church windows.
The dull gray color of lead pipes and cables is caused by the oxygen of the air combining with the metal so as to form a very thin film or skin composed of an oxide of lead. Lead is not at all easily corroded, or eaten away. Unlike iron and steel, it does not need protection by painting. Underneath the film, lead is a bright, shiny bluish-white metal. When you scrape it you notice how soft lead is. It is this softness that makes it easy to squeeze or roll lead into different shapes.
The ease with which lead can be shaped and its resistance to corrosion make it valuable as the outer covering, for electric cables. It protects the insulated wires inside without making the cable too stiff to bend. As lead has become much more expensive, it is used for roofing less often than in the past, and copper or plastics such as polythane are preferred materials, because we have learned that lead is poisonous. Sheet lead is used to line tanks holding corrosive liquids, such as acids, which would eat through other metals.
As lead is heavier than iron or brass, it is used for making weights that must not be too bulky. Some examples are the sinker of fishing tackles and the boots of divers. Lead also melts at a lower temperature, 327 degrees celsius, or 621 degrees farenhaiet than most of the other common metals. Lead’s boiling point is 1,620 degree celsius with a specific gravity, 11.35.