magnesium

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A light, silvery-white, moderately hard metallic element that in ribbon or powder form burns with a brilliant white flame. It is used in structural alloys, pyrotechnics, flash photography, and incendiary bombs. Atomic number 12; atomic weight 24.305; melting point 649°C; boiling point 1,090°C; specific gravity 1.74 (at 20°C); valence 2. See Table at element.

Century Dictionary and Cyclopedia

1. n. Manganese.
2. n. Chemical symbol, Mg; atomic weight, 24.4. The metallic base of the widely distributed alkaline earth magnenesia, which in various combinations, and especially in the form of double carbonate of lime and magnesia, is one of the most abundant of the materials which make up the earth's crust. It is a metal of a brilliant silver-white color, having a specific gravity of 1.75. It melts at a red heat, and boils at a temperature somewhat above that at which zinc volatilizes. When held in the flame of a candle it burns with a dazzlingly white light, which has been seen at sea at a distance of 28 miles. Magnesium was first prepared in a pure state by Bussy; that which had been previously obtained by Davy was impure and not a coherent metal. It is now manufactured on a large scale at various places, especially near Manchester in England, and is pressed when in a semi-fluid state into wire, and then flattened into ribbon, in which form it is generally sold. It is used in taking photographs in places into which the sunlight does not penetrate, in signaling for naval and military purposes, and in pyrotechny, as well as in some operations connected with chemical analysis. The magnesian combinations are widely distributed in nature. From 5 to 6 percent. of the solid material held in solution by the water of the ocean is magnesium sulphate, and from 8 to 11 percent. magnesium chlorid. Next to sodium, chlorin, and sulphuric acid, magnesium is the most abundant ingredient in solution in the ocean. It is, with rare exceptions (as in the case of the genus Serpula), not taken from the ocean by animal life, differing greatly in this respect from lime. Magnesium carbonate, in combination with calcium carbonate, forming dolomite, occurs in enormous quantity among the stratified formations. Beds made up of almost chemically pure dolomite hundreds of feet thick cover thousands of square miles in the valley of the upper Mississippi. Magnesium carbonate also occurs in great abundance, mixed in varying proportions with the calcium carbonate, in much of the rock designated as marble and limestone, which, when this fact becomes known by chemical analysis, are denominated dolomitic. Magnesia also plays the part of base in great numbers of silicates, especially in talc, meerschaum, serpentine, olivine, and the pyroxenes and hornblendes. Magnesian silicates form an important part of numerous meteorites. The pure magnesium carbonate (magnesite) occurs in various localities, but is by no means an abundant mineral. The non-silicated soluble compounds of magnesia are also of rather rare occurrence in nature, but are found in considerable quantity in a few localities, among which that in the vicinity of Stassfurt in Prussia is economically of by far the greatest importance. The combinations found there are kainite, carnallite, and kieserite. (See these words.) Both magnesium sulphate and magnesium chlorid occur in the water of many mineral springs as well as in that of the ocean. The bones of animals and the seeds of various cereals contain a small amount of magnesium phosphate, and the salt is also found in guano. Magnesian salts are used to a limited extent in medicine, especially the sulphate (Epsom salts); they are also used in dressing cotton goods and in dyeing; but, on the whole, the economical importance of the combinations of magnesium, considering their abundance and the cheapness with which they could be furnished in large quantity, is exceedingly small.

Wiktionary

1. n. A light, flammable, silvery metal, and a chemical element (symbol Mg) with an atomic number of 12.

GNU Webster's 1913

1. n. (Chem.) A light silver-white metallic element of atomic number 12, malleable and ductile, quite permanent in dry air but tarnishing in moist air. It burns, forming (the oxide) magnesia, with the production of a blinding light (the so-called magnesium light) which is used in signaling, in pyrotechny, or in photography where a strong actinic illuminant is required. Its compounds occur abundantly, as in dolomite, talc, meerschaum, etc. Symbol Mg. Atomic weight, 24.305. Specific gravity, 1.75.

WordNet 3.0

1. n. a light silver-white ductile bivalent metallic element; in pure form it burns with brilliant white flame; occurs naturally only in combination (as in magnesite and dolomite and carnallite and spinel and olivine)