An alkaline earth, oxide of calcium, CaO, with some impurities, obtained by calcining chalk or limestone so as to expel carbonic acid.

Characters. - In compact masses of a whitish colour, which readily absorb water, and which, when rather less than their weight of water is added, crack and fall into powder with the development of much heat.

Tests. - The powder obtained by the process of slaking, when agitated with distilled water, gives, after filtration, a clear solution which has an alkaline reaction, and is shown by the appropriate tests to contain calcium and only traces of aluminium and magnesium.

Preparations.

B.P

Calcil hydras.

U.S.P

Liquor Calcis.

Potassa cum Calce (p. 608).

Syrupus Calcis.

B.P. Calcii Hydras. Slaked Lime.

Hydrate of lime, Ca(HO)2; 74; with some impurities, recently prepared by pouring 1 pint of water over 2 lbs. of lime in a metal pot.

Solubility. - It dissolves in water, but only sparingly, 11 grs. being dissolved by a pint of water at 60° F.; and, contrary to the usual rule, its solubility is increased by cooling the water, and diminished by heating it.

Its solubility is greatly increased by the addition of sugar, as in the Liquor Calcis Saccharatus, B.P., or Syrupus Calcis, U.S.P.

Preparations.

Liquor Calcis.

Liquor Calcis Saccbaratus.

Dose

1-4 fl. oz. 15-60 min.

Liquor Calcis Saccharatus, B.P.; Syrupus Calcis, U.S.P. Saccharated Solution of Lime, B.P.; Syrup of Lime, U.S.P.

Preparation. - B.P. Like lime-water, mixing 1 ounce of lime with 2 of sugar and using them instead of 2 of lime. This mixture contains 7.11 grains of lime in 1 fluid ounce. U.S.P. Mixing lime (5) and sugar (30) with boiling water (50); diluting with an equal volume of water, filtering, and evaporating to 100 parts.

Dose. - 15 to 60 minims.