In ancient times, humans used lead in everything from cooking tools to water pipes to cosmetics. That was before scientists discovered that lead is poisonous for humans. Today lead is still useful, but we use it with more care in items that hold corrosive materials, like car batteries that hold acid, or to protect us from harmful radiation, like in X-ray machines or nuclear reactors. Pb is lead's symbol, from the Latin word plumbum. This book will...