Greece I. The Most Easterly Division Of Ancient Thessaly, a narrow and mountainous strip of land, containing among others Mts. Ossa and Pelion, and bounded N. by the lower course of the Peneus, on the confines of the Macedonian district of Pieria, E. and S. E. by the AEgean, S. W. by the Paga-saean gulf, and W. by the great Thessalian plain.
II. The Name Of Two Ancient Cities Of Asia Minor.One, a town of Lydia (now Manissa), was situated on the Hermus, at the foot of Mt. Sipylus, and celebrated by the great victory of the Romans over Antiochus the Great of Syria (190 B. C), which made the conquerors masters of a part of Asia Minor. The other, in Caria, was situated on the river Lethaeus in the valley of the Maeander, and had a celebrated temple of Diana, the ruins of which are still visible.
Magnesia, the only known oxide of the metal magnesium, one of the alkaline earths, the compound character of which was discovered by Davy. It consists of 60 Per cent. of magnesium and 40 of oxygen. Like lime, it is found in nature combined with carbonic acid, which may be expelled by calcination at a red heat; the native oxide is called periclase. It is a fine, light, white powder, having neither taste nor smell, almost insoluble in boiling water but less so in cold, of specific gravity 2.3, and known as calcined magnesia. It was regarded as infusible until melted by Dr. Hare with his compound blowpipe. Its properties are alkaline, and it neutralizes all acids. Magnesia exists in the magnesian limestones (see Dolomite), and forms the mineral species magnesite. From these it may be obtained, but the sources that chiefly furnish it are the sulphate of magnesia (see Epsom Salt) of mineral springs, or this salt mixed with chloride of magnesium supplied by the bittern of salt works. Magnesia alba is prepared by mixing together dilute solutions of sulphate of magnesia and carbonate of soda, with or without heating. An interchange of acids and bases takes place, and an insoluble carbonate of magnesia is precipitated, which may be washed with hot water, collected, and dried.
For heavy magnesia a cold saturated solution of carbonate of soda is added to an equal volume of boiling saturated solution of sulphate of magnesia, and three volumes of water. The mixture is boiled till effervescence has ceased, and then more boiling water is added, the whole being continually stirred. This variety is granular, while the light is more or less intermixed with prismatic crystals. The light cubes of magnesia are prepared by removing the precipitate, after it has drained for one or two days in linen strainers, to cubical moulds open at the bottom, and standing in a warm room upon a table of plaster or porous stone, which absorbs the water. After a time the moulds are turned over, so as to present another side to the absorbent surface. Carbonate of magnesia resembles the calcined in its appearance and qualities; it is somewhat more soluble in cold than in hot water, but still requires to dissolve it 9,000 parts of the latter and 2,493 of the former. It contains some water in its composition, but the proportions of its ingredients vary with the methods of its preparation.
The hypochlo-ride of magnesia has bleaching properties equal to those of chloride of lime. - Several salts of magnesia are used in medicine, the most important being the oxide, carbonate, sulphate, and citrate. The oxide and carbonate are frequently used in indigestion, to neutralize an excess of acid in the stomach or to act as gentle laxatives, which they do after combining with any acid. If when administered they do not meet with an acid in the alimentary canal, and consequently do not cause a laxative action, it is desirable to follow their administration with that of lemonade or a similar acid. The simple oxide of magnesia differs from the carbonate in affording by its combination no carbonic acid. Magnesia freshly prepared has been recommended as an antidote in arsenical poisoning, but is less efficient than the hydrated oxide of iron. These substances are used in pharmacy in the preparation of aromatic waters, the fineness of the powders serving to divide minutely the volatile oil with which they are impregnated, and thus present to the menstruum a much larger surface than could be obtained by simple admixture. The sulphate and citrate are considerably used as cathartics. The former is an exceedingly efficient member of the class, and acts without undue violence.
It produces copious and rather watery discharges. It is occasionally combined with other more drastic purgatives, to mitigate their violence. If these salts fail to act as cathartics, which may happen if they are administered in small and repeated doses, they are absorbed and pass out of the system through the kidneys. The effervescent preparations, both solid and liquid, known as citrate of magnesia and popularly used as laxatives, usually contain, in addition, citrate or tartrate of sodium or potassium. The average dose of sulphate of magnesia is an ounce. It acts best when it is freely diluted with water, and should be given on an empty stomach. In cases of nausea, it will often be retained when other cathartics are rejected. It is best suited to inflammatory conditions of the system, and is contraindicated by debility and prostration. A solution of the citrate of magnesia resembles lemonade in taste. - Magnesia in combination with silica enters largely into the composition of many rocks and minerals, such as serpentine, steatite or soap-stone, asbestus, meerschaum, augite, hornblende, and olivine.