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LIME

1072

LIMPET

water. This is used as a medicine and in testing for carbonic acid. When quicklime is exposed to the air for a long time, it takes moisture and carbon dioxide and becomes air slaked. Lime is used in the preparation of mortars and cements, for purifying coal-gas, in making paper-pulp and for removing hair from skins in tanning; and for many centuries it has been used to fertilize the soil. For the last purpose it is now used less than formerly. Carbonate of lime (calcium carbonate) is the most important compound containing this earth. Calcite, the purest form of which is Iceland spar, is crystallized calcium carbonate, while marble, limestone and chalk are more or less pure forms of the substance. Iceland spar is transparent and colorless, and has the power of producing double refraction of light, and hence it is used in the making of certain optical instruments. Calcium carbonate also is the chief constituent of the shells of mollusks, of most of the other shelled creatures and of the hard part of corals. Calcium carbonate dissolves in ordinary waters, since they contain carbonic acid, and from such waters are formed the stalactites and stalagmites found in caverns. The dripping water gradually evaporates and leaves a deposit of calcium carbonate in the beautiful and fantastic forms found on the roofs and floors of caves. Calcium sulphate (sulphate of lime) is another important lime-salt (see GYPSUM). Lime, as phosphate, forms the principal part of the earthy material in the bones of vertebrate (that is, backboned) animals, and it is always found in the ashes of plants. All limestones contain at least traces of magnesium carbonate, and when this is present in large proportion the rock is called dolomite or magnesian limestone. This, like limestone, is often used as a building-stone. Lime in its various combinations is almost universally diffused throughout the earth's crust and in natural waters. The compounds of lime are the chief cause of the hardness of waters.

H. L. WELLS.

Lime, a variety of Citrus medica known as acida, but the name in trade-catalogues is limetta. The plant is a bush or small tree from ten to twenty feet high, and is native to India, being extensively cultivated in Mexico, the West Indies and Florida. It is low, thorny and many-branched, and is tender as regards the cold. There are several horticultural varieties, including the more common sour lime and the sweet lime. The acid fruit is highly valued in tropical countries, and is used for cooling drinks and in cooking.

Lime=LSght, light produced by a blowpipe flame directed against a block of pure compressed quicklime. The lime when warmed beforehand becomes brilliantly incandescent. Lime-light was used on the

stage as far back as 1837-38, but was greatly improved in 1851-52, when Azael was produced at Drury Lane. This light has now been largely replaced by the electric arc-light.

Lim'erick, the capital of Limerick County, Ireland, stands at the head of the estuary of the Shannon, 120 miles from Dublin. The city consists of what is called English Town, the original settlement made in the reign of King John on King's Island; Irish Town, which lies immediately to the south on the left bank of the river; and Newton-Pery, south of Irish Town. Limerick has a graving and floating dock and extensive wharves, and imports grain, petroleum, wine, spirits and timber to the annual value of $3,415,000. Population 38,151.

Lime'stone, the name applied to all rocks composed wholly or chiefly of lime carbonate. Rock composed of the carbonates of lime and magnesia, though technically called dolomite, is often included under limestone. Limestone is widely distributed on all continents and many islands, and is found in all systems of rock, from the oldest sedimentary system to the youngest, and is forming now in many parts of the ocean. Limestone has originated in various ways. Most of it represents the accumulation of the secretions, such as shells, corals etc., of marine animals. Some of it is a chemical precipitate from solution, and a little of it is made up of fresh-water shell accumulations, formed in lakes. Limestone has no distinctive color, but buff and gray colors are common. When limestone becomes crystalline, it is marble. Limestone is often burned for lime, and is extensively used for building stone. Impure limestone is sometimes used for the manufacture of cements, as Portland cement, hydraulic cement etc.

Limoges (le'mozh'), the capital of the French department of Haute-Vienne, is situated on Vienne River, 248 miles from Paris and 128 from Toulouse. The staple industry is the manufacture of porcelain, which employs more than 5,000 workmen. Half of the product is annually exported to America. Population 92,181.

Lim'pet, a mollusk with a conical shell, found incrusting rocks and other objects at low tide. The animal inhabiting the shell is like a flat snail; the foot clings to the rock, and the shell fits over it. In some the shell resembles the old liberty cap in shape. During high tide they wander off and feed on algae, but, as the tide is ebbing, they return to the chosen spot on the same rock which they left a few hours before. There are other forms of limpets which remain permanently attached. These live on rocks, other shells and submerged objects. In many of them there is a deck or partition of shell which helps to hold the animal on.