Lond. Edin. Dub. Lime, Calcis Hydras, Lond. Slacked Lime.

1 From significant of its rank odour.

2 Berzelius.

Syn. Chaux (F.), Kalk (G.), Calce (I). Calviva (S.), Chunamboo (Tarn.), Hoonoo (Cyng.), Soonum (Tel.), Capoor (Malay), Nooreh (Pers.), Chunna(H.), Ahuck (A.), Kakote-tung-o-a (Esquimaux).

This earth is very rarely found in an uncombined state1; but very abundantly in combination with other substances. It forms a part of the bodies of animals and of vegetables; exists in the waters of most rivers, and of the ocean; and is a principal constituent of many fossils, soils, and mountains. The following species only of the fossils in which it is found in combination with carbonic acid require to be noticed: -

By exposing any of these carbonates to a strong heat the carbonic acid is driven off, and lime, or quicklime, as it is commonly called, is obtained; not, however, perfectly pure, but containing generally portions of silex, argil, or magnesia. To obtain very pure lime, let white marble be dissolved in dilute muriatic acid, leaving an excess of marble undissolved. A solution of pure ammonia being added to the solution of marble will indicate by a precipitate the presence of argil and magnesia, which are to be separated by filtration; and the lime itself precipitated in the form of carbonate by a solution of pure sub-carbonate of potassa. This precipitate, after it is washed with water and dried, and exposed to a very violent heat in a platinum crucible, is pure lime.2 It is a white, sonorous, brittle substance, of a sp. gr. 2.3; it is a compound of 1 equivalent of a peculiar metallic base, named calcium by Sir H. Davy, and 1 equivalent of oxygen, making the equivalent of lime 28.5. When lime is mixed with a small portion of water, much caloric is evolved, and the water unites with the lime, forming a hydrate, or slacked lime.

It contains 1 eq. of lime and 1 of water; thence the equivalent of the hydrate is 37.5. The calcareous fossils which are medicinally used are,

1. Chalk. Friable Carbonate of Lime. Officinal. Creta, Lond. Creta alba, Dub. Carbonas Cal-cis, a. Mollior, Creta alba, Edin. Chalk.

1 Monnet affirms that its exists in the mountains of Upper Auvergne, mixed, however, with a little oxide of iron. Monnel's Mineralogy, 515.

2 Chenevix, Memoirs of the Irish Academy, 1802.

Syn. Craie Blanche (F.), Kreide (G.), Wite kryt (Dutch), Kride (Danish), Kalabastrace (Swed.), Mjel (Russian), Gasso(I.), Greda(S. and Port.), Khurree muttie (H.), Kilo (A.), Simic Chunaraboo (Tarn.), Gal sifid (Pers.), Capoor-engrees (Malay),

This mineral is found in the north of France, Poland, some of the Danish islands, and in great abundance in the south of England, within a range which commences at Flamborough Head in Yorkshire, and is continued, with irregular interruptions, in Lincolnshire, Suffolk, Surrey, Sussex, Hampshire, and into Dorsetshire. It occurs massive in beds; and contains numerous relics of land and marine animals.

Qualities. - Chalk is inodorous and insipid; but adheres slightly to the tongue. Its colour is either white, or yellowish, or greyish white. It feels meagre and rough; is not very hard, but is pulverulent; breaks with an earthy fracture; stains the fingers, and marks: its hardness, lustre, and transparency, however, are various. Its specific gravity is from 2.315 to 2.78. It is scarcely soluble in pure water, but is dissolved by water containing carbonic acid in excess. It effervesces with acids; and generally contains a small portion of alumina. The average proportion of lime is 53 per cent. The equivalent of the carbonate is 50.5.

Medical properties and uses, - Chalk is antacid; but it must undergo levigation and washing, before it can be internally administered. In powder it is advantageously employed as an absorbent in burns and excoriations.

Officinal preparations.-Creta preparata, L. E. D. Subcarbonas ammonia, L.

Limestone. Hard Carbonate of Lime. Officinal. Marmor Lond. Marmor album, Dub. Carbonas Calcis, b. Durior, Marmor album, Edin. Limestone.

White Marble.

Syn. Pierre a chaux; chaux carbonatee (F.), Kalkstein (G.), Marino; ossi-carbonato di calce (I.), Chunamboo kulloo (Tarn.), Kakote-tung-o-a (Esquimaux).

Although all the varieties of limestone may be regarded as officinal, yet the two varieties particularly designated are var. a, of the first sub-species, common compact limestone, and a. of the second sub-species, granular foliated limestone, or white Carrara marble. The first is found abundantly in Britain, in extensive strata connected with floetz and coal formations, the second is brought from Carrara and Paros, and belongs exclusively to the primitive and transitive mountains.

Qualities. - Common limestone is inodorous and insipid : of a grey colour, sometimes variegated with veins, stripes, and clouds of yellow, flesh red, and greenish grey. It is hard and brittle; the fracture splintery; the fragments sharp-edged, and scarcely translucent. Its specific gravity is from 2.6 to

2.7. White Marble has a granular texture, white colour, and foliated fracture. Its specific gravity is from 2.7 to 2.84. Both varieties dissolve in acids with effervescence; and contain about 65 per cent. of lime.

Use. - Marble and limestone are chiefly used for obtaining pure lime.