Lime
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 (550oC) (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.
International Standard Bible Encyclopedia (1915)
lim
(1) sidh; compare Arabic shad, "to plaster";
(2) gir; compare Arabic jir, "gypsum" or "quick-lime";
(3) ’abene-ghir):
Sidh is translated "lime" in Isa 33:12, "And the peoples shall be as the burnings of lime, as thorns cut down, that are burned in the fire," and in Am 2:1, "He burned the bones of the king of Edom into lime." It is translated "plaster" in De 27:2, "Thou shalt set thee up great stones, and plaster them with plaster," also in De 27:4. Gir is translated "plaster" in Da 5:5, "wrote .... upon the plaster of the wall." In Isa 27:9 we have, "He maketh all the stones of the altar as chalkstones" (’abhene-ghir).
Everywhere in Palestine limestone is at hand which can be converted into lime. The lime-kiln is a thick-walled, cylindrical or conical, roofless structure built of rough stones without mortar, the spaces between the stones being plastered with clay. It is usually built on the side of a hill which is slightly excavated for it, so that the sloping, external wall of the kiln rises much higher from the ground on the lower side than on the upper. The builders leave a passage or tunnel through the base of the thick wall on the lower side. The whole interior is filled with carefully packed fragments of limestone, and large piles of thorny-burner and other shrubs to serve as fuel are gathered about the kiln. The fuel is introduced through the tunnel to the base of the limestone in the kiln, and as the fire rises through the mass of broken limestone a strong draft is created. Relays of men are kept busy supplying fuel day and night. By day a column of black smoke rises from the kiln, and at night the flames may be seen bursting from the top. Several days are required to reduce the stone to lime, the amount of time depending upon the size of the kiln and upon the nature of the fuel. At the present day, mineral coal imported from Europe is sometimes employed, and requires much less time than the shrubs which are ordinarily used.
See Chalkstone; Clay.