Lime (substance)

Lime (substance), caustic solid substance, white when pure, obtained by calcining limestone and other forms of calcium carbonate. Pure lime, also called quicklime, burnt lime, and caustic lime, is composed of calcium oxide (CaO) but commercial preparations usually contain impurities, such as the oxides of aluminum, iron, silicon, and magnesium. When treated with water, lime liberates large amounts of heat and forms calcium hydroxide, sold commercially as a white powder called slaked lime or hydrated lime. Lime is used in the preparation of cement and mortar and as a neutralizer of acid soils in agriculture. It is also used in the manufacture of paper, glass, and whitewash, in leather tanning, sugar refining, and as a water-softening agent.

Limewater, which is an alkaline solution of slaked lime in water, is used principally in medicine as an antacid, as a neutralizer for acid poisoning, or for treatment of burns.