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DIVISON II.

EARTHY SALTS.

SECTION I.

SALTS OF MAGNESIA.

MURIATE OF MAGNESIA.

Experiment 1. If muriatic acid be saturated with magnesia, a salt will be formed called muriate of magnesia.

Remark. This salt exists in sea water. It is not easily crystallized; it may be obtained in small needles, if concentrated and exposed to a sudden cold. It is very bitter. It is soluble in water. In a dry state it deliquesces. It contains 100 acid and 86.8 base.

Experiment 2. If sulphuric acid be added to muriate of magnesia, sulphate of magnesia will result. Rationale. The sulphuric acid unites with the magnesia, and the muriatic acid is expelled.

FLUATE OF MAGNESIA.

Experiment 1. Fluoric acid combined with magnesia, forms fluate of magnesia; and,

Experiment 2. If the acid be made to unite with the earth in excess; crystals may be obtained in dodecahedrons.

Experiment 3. If sulphuric acid be added to either of these salts, the fluoric acid will be expelled in the form of gas, leaving sulphate of magnesia

BORATE OF MAGNESIA.

Experiment 1. If boracic acid be saturated with magnesia, borate of magnesia will be formed, which will form on evaporation into small irregular crystals. Remark. This salt is soluble in acetic acid. It is decomposed by sulphuric acid, and boracic acid is separated.

PHOSPHATE OF MAGNESIA.

Experiment 1. Phosphoric acid saturated with magnesia, forms phosphate of magnesia. Or,

Experiment 2. If a concentrated solution of phosphate of soda be added to another of sulphate of magnesia; in a few hours crystals of phosphate of magnesia are deposited.

Rationale. The sulphuric acid of the sulphate of magnesia combines with the soda, and the phosphoric acid of the phosphate of soda unites with the magnesia.

Remark. This salt crystallizes in six sided prisms with unequal sides.

PHOSPHATE OF AMMONIA AND MAGNESIA.

Experiment 1. This salt is formed by the union of the two phosphates. Or,

Experiment 2. If urine be evaporated, crystals of this salt will form in four sided transparent prisms, terminated by four sided pyramids.

Experiment 3. If this salt be exposed to a strong heat, it is converted into phosphate of magnesia, the ammonia being evolved.

PHOSPHITE OF MAGNESIA.

Experiment 1. If Phosphorus acid be combined with magnesia, phosphite of magnesia will result.

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Experiment 2. If magnesia and ammonia be combined with phosphorus acid, a triple salt of magnesia and ammonia will be formed.

Remark.

Phosphate of magnesia contains 100 acid, and 62.8 base; the phosphite contains about the same proportions.

CARBONATE OF MAGNESIA.

Experiment 1. If Magnesia be diffused in water, and a stream of carbonic acid passed through it, the carbonate of magnesia will be formed. Or,

Experiment 2. If sulphate of magnesia be decomposed by a fully saturated carbonate of potash, without the application of heat, carbonate of magnesia will be deposited in crystals.

Remark. Crystallized carbonate of magnesia, which is in six sided transparent prisms, consists of 50 acid, 25 magnésia, and 25 water. It is soluble in 480 parts of water. This salt is decomposed by acids, and by various other bodies.

Experiment 2. If sulphate of magnesia be decomposed by sub carbonate of potash, the sub carbonate of magnesia, or magnesia of the shops, will be formed.

Rationale. In both experiments a mutual decomposition ensues; in the former, carbonate of magnesia fully saturated, in the latter carbonate of magnesia containing an excess of base, with sulphate of potash, is produced. See Magnesia.

SULPHATE OF MAGNESIA.

Experiment 1. If diluted sulphuric acid be saturated with magnesia, and the compound evaporated, sulphate of magnesia will be formed.

Remark. This salt called also Epsom salt, because it is obtained from a spring near London, crystallizes in regular four sided prisms or dihedral summits. The crystals of this salt refract doubly. It is intensely bitter. It contains 100 acid, 57.92 base, and 182.8

water. It is decomposed by alkalies; from it magnesia is procured. See Magnesia.

This salt besides being found in the springs of Epsom, exists in sea water, and occurs native. When sulphuric acid is poured on magnesia in the dark, considerable light is produced.

SULPHITE OF MAGNESIA.

Experiment 1. If magnesia be suspended in water, and sulphurous acid gas passed through, a salt will be formed which crystallizes in tetrahedrons, called sulphite of magnesia.

Remark. This salt contains 100 acid, 41 base, and 115 water, On exposure to the air it gradually absorbs oxygen, and is converted into sulphate of magnesia.

NITRATE OF MAGNESIA.

Experiment 1. If nitric acid be combined with magnesia, and the compound evaporated, rhomboidal prismatic crystals of nitrate of magnesia will be the result.

Remark. This salt is found in decayed walls. It is very bitter and deliquescent. It is decomposed by sulphuric acid, and nitric acid is disengaged. It contains 100 acid and 47.64 base.

NITRITE OF MAGNESIA.

Rationale. If nitrate of magnesia be exposed to a sufficient heat, the nitrate is converted into the nitrite of magnesia.

OXYMURIATE OF MAGNESIA.

Experiment 1. When oxymuriatic acid gas is passed through magnesia in a dry state, the oxymuriate of magnesia is formed.

HYPER-OXYMURIATE OE MAGNESIA.

Experiment 1. If magnesia diffused in water, be made to come in contact with oxymuriatic acid gas, in the manner before stated, until saturation is completed, the hyper-oxymuriate of magnesia will be formed.

Rationale. The oxymuriatic acid is converted into hyper-oxymuriatic and common muriatic acid, which unite with the magnesia, forming the hyper-oxymuriate and common muriate of magnesia. This salt resembles the hyper-oxymuriate of lime in its properties, and has been recommended for bleaching. It contains 100 acid, 42.80 base and 23.83 water.

ARSENIATE OF MAGNESIA.

Experiment 1. When arsenic acid is combined with magnesia, to saturation, arseniate of magnesia will be formed.

Remark. This salt does not crystallize, but may be obtained in a gummy mass. If charcoal powder be mixed with this salt and exposed to heat, carbonic acid is formed, and arsenic re-produced.

[blocks in formation]

Experiment 1. When arsenious acid is united with magnesia, the arsenite of magnesia is formed.

Remark. The remainder of the salts of this earth are but little known. They are formed by the union of molybdic, chromic, acetic, benzoic, succinic, camphoric, &c. acids with magnesia, in the manner already noticed.

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