4. Carbonate of magnesia, 2 parts; calcined magnesia, 4 parts; citric acid, 13 parts; lump sugar, 25 parts; essence of lemon, q. s. to flavour. Very agreeable. This is known as ‘Rogés Purgatif,’
Obs. The above are very useful and popular medicines in indigestion, heartburn, nausea, habitual costiveness, dyspepsia, &c.—Dose, 1⁄2 to 2 dessert-spoonfuls, thrown into tumbler 3 parts filled with cold water, rapidly stirred and drank whilst effervescing, early in the morning fasting, or between breakfast and dinner.
MAGNESIAN LEMONADE′. See Citrate of Magnesia and Lemonade (Aperient).
MAGNESIUM. Mg. Syn. Magnium, Talcium. The metallic radical of magnesia. The existence of this metal was demonstrated by Sir H. Davy in 1808; but it was first obtained in sufficient quantity to examine its properties by Bussy in 1830.
Prep. 5 or 6 pieces of sodium, about the size
of peas, are introduced into a test-tube, and covered with small fragments of chloride of magnesium; the latter is then heated to near its point of fusion, when the flame of the lamp is applied to the sodium, so that its vapour may pass through the stratum of heated chloride; when the vivid incandescence that follows is over, and the whole has become cold, the mass is thrown into water, and the insoluble metallic portion collected and dried.
Commercial magnesium is prepared by evaporating solution of the chlorides of sodium and magnesium, in the proportion of 1 to 3, to dryness, mixing with one quarter of its weight of fluor spar and a like amount of sodium, and heating to bright redness in an iron crucible of proper construction.
On a larger scale it is prepared by heating to redness a mixture of chloride of magnesium, 9 parts; fused chloride of sodium, 11⁄2 parts; fluoride of calcium, 11⁄2 parts; and sodium in slices, 11⁄2 parts.
Prop., &c. In colour and lustre it resembles silver, but in chemical properties is more like zinc; its sp. gr. is only 1·743; it is malleable; fusible at a red heat, and can be distilled like zinc; unaffected by dry air and by cold water; burns with brilliancy when heated to dull redness in air or oxygen gas, yielding oxide of magnesium; inflames spontaneously in chlorine, yielding chloride of magnesium; it dissolves in the acids with the evolution of hydrogen gas, and pure salts of magnesium result.
It has been used somewhat extensively as an illuminating agent for photographing at night, and also for the purpose of affording a brilliant light for microscopic and magic lantern effects.