Calcium occurs abundantly in nature and in manufacture. It is found largely as a carbonate in the form of limestone, chalk, marble, etc.; as a sulphate as plaster of Paris, gypsum, alabaster; as a phosphate in the different phosphate rocks and bone ash. Calcium is an exceedingly important constituent of the body, being found, in the form of solution of the phosphate, in every animal tissue and fluid. It gives solidity to bones, and accumulates wherever rapid tissue changes are taking place. The preparations of calcium are antacid and slightly astringent. Locally they are sedative to mucous membrane. Calcium is a valuable antidote in poisoning by oxalic acid, chloride of zinc, and the mineral acids. It can always be obtained for this purpose in the form of wall-plaster or whitewash.
Made from chalk or limestone by calcining (purifying and rendering friable by the action of heat). In this state it has the form of compact white masses, which readily absorb water, crack, evolve heat, and fall into powder. It is then called slaked lime, or quick-lime. If it should come in contact with the eye, it should be washed out with a solution of boric acid.
Lime-water is a saturated solution of lime containing about 3/4 of a grain to ℥ i. of water. It is made by washing slaked lime and shaking it up in distilled water, preferably, though ordinary water may be used. After it settles, the water is poured off from the sediment and strained. It is colorless, inodorous, and has a disagreeable alkaline taste. By exposure to the air it absorbs carbonic acid, and should therefore always be kept well corked. Lime-water acts as a gastric sedative, and added to milk prevents its curdling in large lumps. The ordinary proportion is lime-water ℥ ss. to milk ℥ v., increased, according to circumstances, to 1/3 or even 1/2 lime-water. Lime-water is slightly constipating.
To one part of slaked lime, as above, four parts of water are added. This, mixed thoroughly with infectious stools, and added until the mixture gives a strong alkaline reaction when tested with litmus paper, is considered an efficient disinfectant for cholera and typhoid stools. Next to it in value comes chloride of lime, which is not effective unless fresh. This is to be made in a solution of six ounces to one gallon of water.
Made from chalk by a cleansing and drying process. A smooth white powder, insoluble in water, and of astringent action. Externally, it is used as a dusting-powder. When taken internally it may be administered in glycerin or syrup. Average dose, gr. xv.-I Gm.
Contains prepared chalk, and is an astringent. It must be freshly made. Dose, ℥ ss.-15 mils.