Calx. Lime, Oxide of Calcium.
Lime exists abundantly in mineralogy, but is never found in an uncombined state. It is an oxide of the metal calcium; and being strongly ‘basic, and having, in the cold, an intense affinity for carbonic acid, it is found as carbonate of lime in all species of marble, and in the blue and gray limestones; chalk, oyster shells, etc. White marble and oyster shells contain the purest forms of the carbonate; while all limestones are more or less contaminated by mineral and earthy compounds. The carbonic acid may be driven off at a full red heat-in which respect the lime carbonate is directly the opposite of the soda and potassa carbonates. Marble or shells should always be used in preparing lime for pharmaceutical purposes; and these may be heated in a lightly covered crucible for three hours.
Lime is a grayish-white, strongly alkaline, and caustic earth. It absorbs carbonic acid when cold; whence exposure to the air will slowly return it to a carbonate. It also absorbs moisture, and crumbles down as " slaked " (hydrated) lime. An excess of water added quickly, is absorbed with the development of considerable heat. Hydrated lime is much less caustic than the dry or anhydrous. Milk of lime is a hydrate stirred into a thick liquid with an excess of water. Lime dissolves in water to a limited extent–less than four ounces of unslaked lime being sufficient to saturate a gallon of distilled water. Like the other alkalies, it forms soapy compounds with the oils; but its soaps are insoluble.
Properties and Uses: Lime is used to neutralize acids in various pharmaceutical operations; also in the manufacture of the disinfectant, chloride of lime. Lime water is a weak antacid, and sometimes is used in doses of half to a whole fluid ounce, in milk, three times a day, for sourness of the stomach and the acid forms of dyspepsia; but, like all other alkalies, can not do more than give transient relief by neutralizing the acid present, and absorbing the carbonic acid gas which arises from fermenting food. It is not, therefore, a remedy, but a palliative; and though not so strong an alkali as some others, (the water never taking up more than a fixed quantity of lime,) its continued repetition will do harm. A lump of several ounces, wrapped in a piece of damp flannel and placed under the bed-clothing, will evolve so much heat in slacking as to procure a fair sweat. It is a popular remedy in some sections for recent colds.
The Physiomedical Dispensatory, 1869, was written by William Cook, M.D.
It was scanned by Paul Bergner at http://medherb.com