Cooley's Cyclopaedia of Practical Receipts Volume Ii Part 41

_c._ (Pharm. Journ.) Sulphate of magnesia and bicarbonate of soda, of each 1 lb.; tartaric acid, 1/2 lb.; mix as before. The last two are much less agreeable than the others.

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 'ROGeS 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 quant.i.ty 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 pa.s.s through the stratum of heated chloride; when the vivid incandescence that follows is over, and the whole has become cold, the ma.s.s 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, 1-1/2 parts; fluoride of calcium, 1-1/2 parts; and sodium in slices, 1-1/2 parts.

_Prop., &c._ In colour and l.u.s.tre it resembles silver, but in chemical properties is more like zinc; its sp. gr. is only 1743; 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.

=Magnesium, Bromide.= _Syn._ MAGNESII BROMIDUM. To bromide of iron in solution add calcined magnesia in excess, heat the mixture, filter, and evaporate the clear solution to dryness.

=Magnesium, Carbonate of (Light).= _Syn._ LIGHT CARBONATE OF MAGNESIA; CARBONATE OF MAGNESIA; MAGNESIA; MAGNESIae CARBONAS LEVIS (B. P.).

3MgCO_{3}.MgO.5H_{2}O. _Prep._ 1. (Ph. L.) Sulphate of magnesium, 4 lbs., and carbonate of sodium, 4 lbs. 9 oz.; boiling distilled water, 4 galls.; dissolve the salts separately in one half the water, filter, mix the solutions, and boil for 2 hours, constantly stirring with a spatula, distilled water being frequently added to compensate for that lost by evaporation; lastly, the solution being poured off, wash the precipitated powder with boiling distilled water, and dry it. The formulae of the Ph. E.

& D. are essentially the same, except that the ebullition is limited to from 10 to 20 minutes.

2. (B. P.) Similar to the foregoing except that precipitation takes place in the cold. The formula of this compound is (Mg.CO_{3})_{3}.

Mg(HO)_{2}.4(H_{2}O).

3. (HENRY'S.) Ordinary carbonate of magnesia, the washing of which has been finished with a little rose water.

4. Add a solution of carbonate of pota.s.sium or sodium to the bittern or residuary liquor of the sea-salt works, and well wash and dry the precipitate as before. This is known in commerce as 'Scotch magnesia.'

_Obs._ The carbonate of magnesia of commerce is usually made up into cakes or dice while drying; or it is permitted to drain and dry in ma.s.ses, which are then cut into squares with a thin knife. It is powdered by simply rubbing it through a wire sieve. The presence of iron in the solution of the sulphate of magnesium, when the crude salt is employed, and which is destructive to the beauty of the preparation may be got rid of by the addition of lime water until the liquor acquires a slight alkaline reaction, and subsequent decantation after repose.

=Magnesium, Carbonate of (Heavy).= _Syn._ HEAVY CARBONATE OF MAGNESIA; MAGNESIae CARBONAS (B. P.). 3MgCO_{3}.MgO.5H_{2}O. _Prep._ 1. Apothecaries'

Hall. A saturated solution of sulphate of magnesium, 1 part, is diluted with water, 3 parts, and the mixture heated to the boiling point; a cold saturated solution of carbonate of sodium, 1 part (all by measure), is then added, and the whole is boiled with constant agitation until effervescence ceases; boiling water is next freely poured in, and after a.s.siduous stirring for a few minutes, and repose, the clear liquid is decanted, and the precipitate thrown on a linen cloth and thoroughly washed with hot water; it is, lastly, drained, and dried in an iron pot.

2. (Ph. D.) Dissolve sulphate of magnesium, 10 oz., in boiling distilled water, 1/2 pint; and carbonate of sodium (cryst.), 12 oz., in boiling distilled water, 1 pint; mix the two solutions, and evaporate the whole to dryness by the heat of a sand bath; then add of boiling water 1 quart, digest with agitation for half an hour, and wash the insoluble residuum as before; lastly, drain it, and dry it at the temperature of boiling water.

3. (B. P.) White granular powder precipitated from a boiling solution of sulphate of magnesium by a solution of carbonate of sodium, the whole evaporated to dryness, and the dry residue digested in water, collected on a filter, and washed.

_Prop._ The ordinary or light carbonate of magnesia is a white, inodorous, tasteless powder, possessing similar properties to calcined magnesia, except effervescing with acids, and having less saturating power. An ounce measure is filled by 45 to 48 gr. of the powder lightly placed in it. The heavy carbonate is sometimes fully thrice as dense (see _below_), but in other respects is similar.

_Dose._ As an antacid, 1/2 to a whole teaspoonful, 3 or 4 times daily; as a laxative 1/2 dr. to 2 dr. It is commonly taken in milk. It is apt to produce flatulence, but in other respects is preferable to calcined magnesia.

_General Remarks._ Although commonly called 'carbonate of magnesia,' the above substance, whether in the light or heavy form, appears to be a compound of carbonate with hydrate, in proportions which are not perfectly constant. (For B. P. formula see preceding article.) On account of the excess of base in its composition it was formerly regarded as a subsalt (subcarbonate of magnesia). A great deal has been written uselessly respecting the preparation of these carbonates, about which, however, there is neither mystery nor difficulty, as some writers would lead their readers to suppose. If the solutions are very dilute, the precipitate is exceedingly light and bulky; if otherwise, it is denser. By employing nearly saturated solutions, and then heating them and mixing them together whilst very hot, a very heavy precipitate is obtained, but it is apt to be gritty or crystalline. The same occurs when cold solutions are mixed, and no heat is employed. The lightest precipitate is obtained from cold, highly dilute solutions, and subsequent ebullition of the mixture.

Mr Pattinson, a chemist of Gateshead, prepares a very beautiful and pure heavy carbonate from magnesian limestone. The latter is calcined at a dull red heat (not hotter) for some time, by which the carbonic anhydride is expelled from the carbonate of magnesium, but not from the carbonate of calcium, which hence continues insoluble. The calcined ma.s.s is next reduced to a milk with water in a suitable cistern, and the carbonic anhydride resulting from its own calcination forced into it under powerful pressure. The result is a saturated solution of carbonate of magnesia, the lime remaining unacted on so long as the magnesium is in excess. The solution by evaporation yields the heavy carbonate, whilst carbonic anhydride is expelled, and may be again used in the same manufacture. 154 to 160 gr. of the heavy carbonate are required to fill an ounce measure when lightly placed in it, by which it appears to be fully thrice as dense as the light carbonate. The bicarbonate of magnesium (magnesiae bicarbonas, L.) exists only in solution. The so-called 'fluid magnesias' of Murray, Dinneford, Husband, &c., are solutions of this salt. The small prismatic crystals which are deposited when 'fluid magnesia' is exposed to the air for some time consist of hydrated neutral carbonate, and not bicarbonate, as is sometimes stated.

=Magnesium, Chloride of.= MgCl_{2}. _Syn._ MAGNESII CHLORIDUM, L. _Prep._ (Liebig.) By dissolving magnesia in hydrochloric acid, evaporating to dryness, adding an equal weight of chloride of ammonium, projecting the mixture into a red-hot platinum crucible, and continuing the heat till a state of tranquil fusion is attained. On cooling, it forms a transparent, colourless, and very deliquescent ma.s.s, which is anhydrous, and soluble in alcohol.

_Obs._ Without the addition of the chloride of ammonium it is impossible to expel the last portion of the water without at the same time driving off the chlorine, in which case nothing but magnesia is left. The fused ma.s.s should be poured out on a clean stone, and when solid broken into pieces, and at once transferred to a warm, dry bottle. The P. Cod. orders the solution to be evaporated to the sp. gr. 1384, and to be put, whilst still hot, into a wide-mouthed flask to crystallise.--_Dose_, 1 to 4 dr.; as a laxative.

=Magnesium, Cit'rate of.= Mg_{3}(C_{6}H_{5}O_{7})_{2}. _Syn._ MAGNESIae CITRAS. L. _Prep._ There is some difficulty in obtaining this salt in an eligible form for medicinal purposes. When precipitated from a solution it is insoluble. The following formulae can be highly recommended.

1. (Parrish.) Dissolve crystallised citric acid, 100 gr., in water, 15 drops, and its own 'water of crystallisation' by the aid of heat; then stir in calcined magnesia, 35 gr.; a pasty ma.s.s will result, which soon hardens, and may be powdered for use.

_Obs._ The chief practical difficulty in this process results from the great comparative bulk of the magnesia, and the very small quant.i.ty of the fused ma.s.s with which it is to be incorporated. A part of the magnesia is almost unavoidably left uncombined, and the salt is consequently not neutral. The uncombined earth should be dusted off the ma.s.s before powdering the latter. A high temperature must be avoided.

2. (Robiquet.) Citric acid, 35-1/4 parts, is powdered and dissolved in boiling water, 10-5/8 parts; when the solution is cold, and before it crystallises, it is poured in a wide earthen vessel, kept cold by surrounding it with water; then, by means of a sieve, carbonate of magnesium, 21-1/6 parts, is distributed evenly and rapidly over the surface without stirring; when the reaction ceases the mixture is beaten rapidly as long as it retains its pasty consistence. The salt should be dried at a temperature not exceeding 70 Fahr.

3. (Effervescing; MAGNESIae CITRAS EFFERVESCENS, L.)--_a._ Citric acid (dried and powdered), 7 parts; heavy carbonate of magnesium, 5 parts; mix, and preserve in well-corked bottles.

_b._ (Ellis.) Mix powdered citric acid, 2-1/2 oz., with powdered sugar, 8 oz.; triturate to a fine powder, and drive off the water of crystallisation by the heat of a water bath; add citrate of magnesium (prepared by fusion), 4 oz., and oil of lemons, 10 drops, and mix intimately; then add bicarbonate of sodium, 3 oz., and again triturate until the whole forms a fine powder, which must be preserved in stoppered bottles. From 1 to 3 tablespoonfuls, mixed in a tumbler of water, furnishes an effervescing draught in which the undissolved portion is so nicely suspended, that it can be taken without inconvenience.

_c._ (Ph. Germ.) Light carbonate of magnesia, 25 oz.; citric acid, 75 oz.; distilled water, q. s.; mix into a thick paste and dry at 86 Fahr. With 14 oz. of the dried ma.s.s mix bicarbonate of soda, 13 oz.; citric acid, 6 oz.; sugar, 3 oz. Sprinkle over the mixture enough rectified spirit so as to make it sufficiently moist to be granulated by rubbing through a tinned iron sieve.

_d._ (Extemporaneous.) Citric acid (cryst.), 20 gr.; carbonate of magnesium, 14 gr.; mix in a tumbler of cold water, and drink the mixture whilst effervescing. A pleasant saline.

_Obs._ A dry white powder, sometimes sold as citrate of magnesia in the shops, is quite a different preparation to the above, and does not contain a particle of citric acid. The following formula is that of a wholesale London drug-house that does largely in this article:--

Calcined magnesia, magnesium oxide, 1-1/4 lb. (or carbonate, 2 lbs.); powdered tartaric acid, 1-1/2 lb.; bicarbonate of sodium, 1 lb.; dry each article by a gentle heat, then mix them, pa.s.s the mixture through a fine sieve in a warm dry room, and keep it in well-corked bottles. A few drops of essence of lemon and 3 lbs. of finely powdered sugar are commonly added to the above quant.i.ty. This addition renders it more agreeable.

_Prop., &c._ Citrate of magnesium is a mild and agreeable laxative; its secondary effects resemble those of the carbonate.--_Dose._ As a purgative, 1/2 to 1 oz. The dose of the effervescing citrate must depend on the quant.i.ty of magnesia present. A solution of this salt in water, sweetened and flavoured with lemon, forms magnesian lemonade.

=Magnesium, Boro-cit'rate of.= _Syn._ MAGNESIae BORO-CITRAS, L. _Prep._ (Cadet.) Boracic acid (in powder), 113 gr.; oxide of magnesium, 80 gr.; mix in a porcelain capsule, and add enough of a solution of citric acid, 260 gr., in water, 3-1/2 pints, to form a thin paste; then add the remainder of the citric solution, and gently evaporate, with constant stirring, to dryness. A cooling saline, and, in small doses, emmenagogue and lithontriptic.--_Dose._ As an aperient, 3 to 6 dr.

=Magnesium, Oxide of.= MgO. _Syn._ OXIDE OF MAGNESIUM, CALCINED MAGNESIA, MAGNESIA (B. P., Ph. L.).

_Prep._ 1. (B. P.) Magnesium carbonate, heated in a crucible until all the carbonic anhydride is driven off.

_Prop., &c._ White heavy powder, scarcely soluble in water, but readily soluble in acids without effervescence. Its solution in hydrochloric acid, neutralised by a mixed solution of ammonia and ammonium chloride, gives a copious crystalline precipitate when sodium phosphate is added to it. See next preparation.

=Magnesia levis= (B. P.) _Syn._ LIGHT MAGNESIA. _Prep._ (B. P.) 1. Light carbonate of magnesium heated in a Cornish crucible until all the carbonic anhydride is driven off.

A bulky white powder, differing from the magnesia (B. P.) only in its density, the volume occupied by the same weight being 3-1/2 to 1.

The properties of the two varieties of magnesium oxide are identical, and are used in medicine as antacids, laxatives, and antilithics, and much used in dyspepsia, heartburn, &c.--_Dose_, 10 to 20 gr. as an antacid and 20 to 60 gr. as a purgative.

=Magnesium, Phos'phate of.= MgHPO_{4}.6Aq. _Syn._ MAGNESIae PHOSPHAS, L.

_Prep._ From the mixed solutions of phosphate of sodium and sulphate of magnesium, allowed to stand for some time. Small, colourless, prismatic crystals, which, according to Graham, are soluble in about 1000 parts of cold water. Phosphate of magnesium exists in the grains of the cereals, and in considerable quant.i.ty in beer. It is also found in guano.

=Magnesium and Ammo"nium, Phosphate of.= MgNH_{4}.PO_{4}, 6 Aq. _Syn._ AMMONIO-PHOSPHATE OF MAGNESIA; MAGNESIae ET AMMONIae PHOSPHAS, L. This compound falls as a white crystalline precipitate whenever ammonia or carbonate of ammonium is added, in excess, to a solution of a salt of magnesium which has been previously mixed with a soluble phosphate, as that of soda. It subsides immediately from concentrated solutions, but only after some time from very dilute ones.

_Prop., &c._ Ammonio-phosphate of magnesium is very slightly soluble in pure water; when heated, it is resolved into pyrophosphate of magnesium, and is vitrified at a strong red heat. It is found in wheaten bran, guano, potatoes, &c., and occasionally forms one of the varieties of urinary calculi.

=Magnesium, Sil'icates of.= There are several native silicates of magnesia, more or less pure, of which, however, none is directly employed in medicine. Meerschaum and steat.i.te or soapstone are well-known varieties. Serpentine is a compound of silicate and hydrate of magnesium.

The minerals augite and hornblende are double salts of silicic acid, magnesium, and calcium with some ferrous oxide. The beautiful crystallised mineral called chrysolite is a silicate of magnesium, coloured with ferrous oxide. Jade is a double silicate of magnesium and aluminum, coloured with chromic oxide.