LIME, a white caustic alkaline earth (calcium oxide or quicklime). The term also is loosely used to refer to calcium hydroxide (slaked lime) or calcium carbonate (limestone, chalk, marble [q.v.]). Calcium oxide is obtained by heating calcium carbonate to dull redness (550^oC) (cf. Isa 33:12). Carbon dioxide is given off and, if it is swept away in a current of air, as in a kiln, dissociation proceeds until the reaction is practically complete. The calcium oxide which is left looks like white ash (cf. NEB Isa 33:12). With the addition of water to quicklime, heat is evolved, clouds of steam are given off and the lime combines with the water, cracks, and after addition of sufficient water, crumbles down to a fine, dry, white powder (calcium hydroxide or slaked lime).

The chief use of lime is in the preparation of mortar, for building purposes, made from a thick paste of slaked lime together with three to four times as much sand as quicklime originally taken. In the hardening of the mortar there is no combination between the lime and the silica of the sand, the hardening consisting of the evaporation of the moisture, or by its absorption by the bricks and a slow reaction of the lime with atmospheric carbon dioxide producing calcium carbonate.

The burning of bones produces a grayishwhite ash, composed mainly of calcium phosphate, which resembles lime in appearance (cf. RSV and NEB Amos 2:1).

Bibliography J. R. Partington, A Textbook of Inorganic Chemistry, 6th ed. (1950), 754, 755.