The element magnesium (L. magnesi(a) + um, district in Thessaly; also name of two cities in Asia Minor) occupies an intermediate place between metals of the alkalies and alkaline earths, with which latter it once was classed, but now has been separated, owing to its closer recognized analogies to zinc, both having volatile chlorides, soluble sulphates, and isomorphous salts. Magnesium occurs abundantly in nature as chloride and sulphate, in Stassfurt salt-mines, also in numerous spring waters; as carbonate in magnesite; as magnesia calcic carbonate in dolomite (magnesia lime-stone), which is so profuse in places as sometimes to form the greater bulk of mountain ranges; as silicate in asbestos, meerschaum, serpentine, soapstone, talc, etc.
The metal is obtained by the action of metallic sodium on magnesium chloride - MgCl2 + 2Na = 2XaCl + Mg. It is silver-white, losing lustre by oxidization; when heated to redness yields brilliant white light, and MgO; like potassium and sodium, decomposes hot water - Mg + 2H2O = Mg(OH)2 + 2H. It is not official, but several of its important salts are.
Tests for Magnesium Salts: 1. With caustic alkalies get gelatinous, white precipitates, insoluble in excess, but soluble in ammonium chloride. 2. With potassium or sodium carbonate + heat get white precipitate of basic carbonate, 4MgCO3,Mg(OH)2. 3. With sodium phosphate + ammonium chloride and ammonia get white crystalline precipitate of magnesium-ammonium phosphate, MgNH4PO4. 4. Salts are white and soluble, except carbonate, phosphate, arsenate; oxide and hvdroxide also are insoluble, the latter being precipitated by NaOH or KOH.
Magnesii Sulphas. Magnesium Sulphate, MgSO4 + 7H2O. - (Syn., Mag. Sulph., Epsom Salt, Sal Amarum - Epsomense - Anglicum or Sedlicense, Sulfas Magnesicus; Fr. Sulfate de Magnesie, Sel d'Epsom, Sel (amer) de Sedlitz; Ger. Magnesium sulfuricum, Magnesiumsulfat, Schwefelsaure Magnesia, Bittersalz.)
Manufacture: 1, Chiefly obtained from Stassfurt, as kieserite (MgSO4,H2O); heat mineral, dissolve in water, crystallize; 2, By dissolving magnesite (native (MgCO3)) in diluted sulphuric acid, filtering, crystallizing - MgCO3 + H2SO4 = MgSO4 + H2O + CO2; 3, By heating dolomite (MgCO3,CaCO3) to dissipate CO2, treating residue with HC1 to take up calcium, and dissolving the remaining magnesium in H2SO4. It is in small, colorless, prismatic needles or rhombic prisms, odorless, cooling, saline, bitter taste, slowly efflorescent, soluble in water (1), boiling water (.2), almost insoluble in alcohol; aqueous solution (1 in 20) neutral; exposed to warm air loses some water of crystallization, forming a white powder, further heating removes more water, and above 200° C. (392° F.) becomes anhydrous; contains 48.59-53.45 p. c. of anhydrous magnesium sulphate, corresponding to 99.5 p. c. of the crystallized salt. Tests: 1. Aqueous solution (1 in 20) with ammonium chloride T. S., ammonia water, and sodium phosphate T. S. - white, crystalline precipitate; 2. Aqueous solution with barium chloride T. S. - white precipitate, insoluble in hydrochloric acid. Impurities: Heavy metals, arsenic, chloride. Should be kept in well-closed containers. Dose, ℥ss-l (15-30 Gm.), in cold water or effervescing solution.
Preparations. - 1. Infusum Sennae Compositum, 12 p. c.
Unoff. Preps.: Liquor Magnesii Sulphatis Effervescens, 25 Gm., + citric acid 4, syrup of citric acid 60, potassium bicarbonate 2.5, dist.
Fig. 458. - Magnesium sulphate crystal.
water q. s. 100, dose, the entire contents of bottle. Magnesii Sulphas Effervescent, 50 p. c.
Properties and Uses. - Cathartic, producing safe, painless, watery stools, refrigerant, diuretic; fevers, inflammatory affections, colic, constipation, dysentery, septic fever, intestinal obstruction, pleurisy, painter's (lead, barium) colic.
Incompatibles: Alkaline carbonates, lime water, phosphoric acid, phosphates, lead acetate, silver nitrate.
Magnesii Carbonas. Magnesium Carbonate, (MgCO3)4, Mg(OH)2 + 5H2O. - (Syn., Mag. Carb., Carbonicas Magnesicus, Magnesia (Alba) Hydrico-carbonica; Br. Magnesii Carbonas Levis; Fr. Carbonate de Magnesie, Magnesie blanche; Ger. Magnesium carbonicum, Basisches Magnesiumcarbonat, Kohlensaure Magnesia, Weisse Magnesia.)
Manufacture: Mix strong boiling aqueous solutions of magnesium sulphate and sodium carbonate, wash precipitate to remove sodium chloride, dry without heat - 5(MgSO4 + 7H2O) + 5(Na2CO3 + 10H2O) = [(MgCO3)4 + Mg(OH)2 + 5H2O] + 5Na2SO4 + CO2 + 79H2O. If a heavier salt is desired (for heavy magnesium oxide), digest the salts in water and evaporate to dryness without filtering, then lixiviate the mass with water to wash out Na2SO4, leaving magnesium salt to be dried. It is in light, white, friable masses, bulky white powder, odorless, slight, earthy taste, permanent, practically insoluble in alcohol, water, but imparts to it slight alkalinity, soluble in dilute acids with effervescence; strongly heated loses water and carbon dioxide, forming magnesium oxide; contains hydrated magnesium carbonate and magnesium hydroxide, corresponding to 39.2 p. c. of magnesium oxide and .8 p. c. of calcium oxide. Tests: 1. Dissolve in diluted hydrochloric acid, add ammonium chloride T. S., an excess of ammonia water, and sodium phosphate T. S. - white crystalline precipitate. Impurities: Heavy metals, iron, calcium oxide, soluble salts. Dose, antacid, gr. 5-20 (.3-1.3 Gm.); laxative, 3ss-l (2-4 Gm.), in water, milk.
Preparations. - 1. Magma Magnesiae. Magnesia Magma. (Syn., Magma Mag., Milk of Magnesia; Fr. Lait de Magnesie; Ger. Mag-nesiamilch.
Manufacture: Mix magnesium carbonate 12.5 Gm. with enough distilled water (50 Ml. (Cc.)) for smooth mixture; dissolve sodium hydroxide 8 Gm. in distilled water 40 Ml. (Cc), and add it to the magnesia mixture, constantly stirring, agitate frequently for 15 minutes, wash resulting magma, by decantation, several times, each with distilled water 200 Ml. (Cc.) - until red color produced in 5 Ml. (Cc.) of the washings by .3 drop of phenolphthalein T. S. is discharged by .1 drop of diluted sulphuric acid; allow precipitate to subside until it measures 100 Ml. (Cc), decant supernatant liquid, transfer to wide-mouthed bottle, tightly stopper with cork dipped in melted paraffin. For the distilled water may substitute water boiled with powdered magnesium carbonate (.5 Gm. in each 100 Ml. (Cc.)) and filtered; may add, if desired, oil of peppermint or oil of anise .05 Ml. (Cc.), or other suitable flavoring. It is a thick, white, alkaline liquid consisting of magnesium hydroxide suspended in water; contains 6.5-7.") p. c. of magnesium hydroxide, Mg(OH)2. Tests: Add to 1 ML (Cc.) diluted hydrochloric acid 2 Ml. (Cc.) - few isolated bubbles, solution slightly turbid; add ammonium chloride .5 Gm., filter, render alkaline with ammonia water - no precipitate, but upon adding sodium phosphate T. S. - white precipitate. Dose, 3j-2 (4-8 Ml. (Cc.)).