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Aqua aluminis composita, P. L. I 787. Aqua aluminosa bateana, P. L. 1745.
Boi ling Water, t o PintS. Dissolve at the sume time the alum and sulphate os gine in the water, and theu Strain the solution through Paper.
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In the former Pharmacopoeia lime was ranked among th articles of Mat in Medica, and taken as prepared fur iis coarser lases in the pris: sor many pu oses this might bes allicient, but sor others it is osten important that it shouldbe inuch purer, and the present directions are there re introduce l. Tino varieties of the carbonale also are talien
alWays the sanae substance, possessing the fame characters,
Inil producing the samo effecis, though it may differ in the
proportion os heterogeneous in attors With whicli it is mix ea; the distinctions theres ore which were formerly made be- tween iis medicat qualities as ctia ined from different solarces vere superfluous, and will not, in the present state os science, be lihely to he rene volt hv the present introduction os more than one. E is necessary to the perfection of the limethat the carbonic aeut should be entiret y expelled, and in therreparation os ordinaryclime this is very imperfeci ly done, Ior it is sum cient for ali common purposes is it be buriat soas to stalae ora the addition Os Water; on the other hand, it may also be noticed that Where lime-stone is employed, thelieat maJ be pushed too far and be too long continuest. The rure eartiis Will not vi trisy by heat, but many earthy admix
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Aqua calcis, P. L. I 787. Aqua calcis simplex, P. L. 1745. Aqua calcis, P. L. II2O.
diately, and let it sta nil for three ho urs; thenkeep the solution opon the re maining lime in Stopped glass botiles, and pour ost theclear liquor When it is ruanted sor USC.
Lime is solubio in about 450 times iis meight os mater, orlitile more than one grain in one fluidounce, forming a trans- Parent solution; hence the proportion here directed is in
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Dct more than is required for the saturation of the wpter, but the larger quantity alloWs moroover Dr any in1- purity contained in the lime, and as it is a cheap articie, thequantity used is scarce of any importance. The procoss herfzdopted is simple, enicaci ous, and convenient, and by keepingilie solution standing Dpon the lime it mill alWays be saturaled, and the place of any crust os carbonate of lime whichforins iapon the furface, is exposed, mill be supplied froin thelime, Whicli remaliis in a state ready for solution.
Creta si a parata, P. L. t 787. P. L. II 45. Creta, P. L. 1720.
This is the most certain method of obtaining the poWderianisorin and fine. The principie has long been adopted for the preparation of Other fine and equat powders of insolubie substances . and is so in the common manufacture ofWhitening ; it was also employed in the early Pharmacopoeiae; it turias Iapon the longer suspension of the siner particles ita
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vpater, So that, after the subsidence of the coarser in the firstinstance, the uniform and very subile poWder Whicli remains longer Suspended, mav be collected as the produci os a second subsideiace. In the previ ous mechanical di iston, orgrin ling, a smali quantity of Water is added to prevent thesitur particios froni stying olf.
Tahe of Sulphate os Magnesia, Subcarbonate of Potass, of cacha POUnd. Vater, iliree gallon'. Dissolve the sub carbonate os potass in three pinis of the water, and stratia: dissolve also the sulpha te os magnesia separately in sive pinis of the water, and stratia: then additio rest of the water to the lalter solution, apply heat, and When it boils, pour in thes Ormer Solution, Stiri ing them Weli toaether: nexi struin through a linen cloth: lastly, Wash
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of whicli it is the object to collect as Deo as possibi e froin the last. Helice, as the newly formed sulphate os potass requires a large proportion of water for iis solution, such a proportion is directed in the frst instance, and it is asterwardswelt washed with more. Is water bo impregnat ed with carbonic acid gas it will dissolve carbonate os magnesia, and herace the liquor is made to boit for the purpose os delachingit. Is the tu o solutions be mixed cold, and the precipitate lest for sonae days upon the filter Without artificiat drying, many large and perfeci crustals of carbonate os magne,ia Will
saturalest With carbonic acid, as in the crystals for in iis omclinary forna it is a subcarbonate , IOD paris contain carbonicacid 5O, magnesia 25, Water 25 ; and is not so saturaled, hut in iis state of sui sali, carbonic acid l8, magnesia 60,
water I 2. In commerce, the muriate os magnesia contained in theresiduary liquor after the crystalli Zation os muriate of sodasrom Sea water is decomposed by a similar process, and yieldaa large proportion of the ordinary magnesia os the maineis.
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It may he notod that a dc finite quantity has been pre- scribed here and in many other cases for the- salae of precision only, and Dot as influenci g the quali ty of the produci. This preparation Was the magnesia usta of the former Pharmacopoeia: but as the term magnesia is correctly used toexpress only the pure earth, so it has been thought proper toapply it decidedly in the present instance, although, in commori lan age, the Same term may be most generalty appliedio the carbonate. and the epithet calcanes ad ted to expressthe present preparation. The proces s depends upon the expulsion of the carbonic acid of the carbonate by heat, and in the sorin os gas, and lience the carbonate 3ields about halfits Weight, or rather Attis of the pure magnesia. It may be considered as insolubie in xvater, for ΚirWan states I900 timeaiis Weight to be necessary for xliis purpose at 60'.
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Flores sulphuris loti, P. L. 1787.
Sublimed sulphur prepared upon a large scale contain et some sulphuric acid, Whichis evident to the taste, and thesedi rections are intended to remove it. It is farther pro-Per, that sulphur, When Washed, should be hept in closed Nesseis rather than in an open drawer; for in the laltersituation iis superior surface manifestly becomes acid onlong keeping.
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Tahe of sublimod Sulphur, a poUnd. Fres h Lime, throe Potand 8. Boii the sulphur and lime together in Water, then stra in tho solution ibi ough paper,nnii di op in as much muriatio ac id us may beneCCSSury to precipitatu the sulphur: lusit Wa Sh this by res cuted affusioris of Caici unt il
In the Pharmacoposa of I745 a sulpitur et os lime was formed, or rather an hydroguretted mlphuret, as it Wasprepared in Water like the process no v adopted, and the Sulphur precipitaled froin the solutiora bu sulphuric acid; in that os i7SI sulphuret of potass was decomposed bu the Same acid. The insolubie sulphate os lime could scat coly bewashed out froin the former, and the sulphate os potass notwithout dissiculty frona the lalter; both the fore containodadmixtures of these salis, to which they o ed a good dealos their White appe anco. The present precipitate, si omthe ready solubility of tho muriate of lime, Will be only sulphur, but it will be stili much whiter ilian sublimed sulPhur, ei ther Dom iis more minute division, or sonae Other Cala Se notweli ascertained. It will, howeveri differ in no other respect om sublimed sulphur, and has probab ly for this reason
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poetae; but as illis circumstance of colour gives it an advantage in the composition of Oint menis, So as n resinement, rather than necessary agent in practice, it is here retainta.
Oleum sulphoratum, P. L. I 78I. Balsamum sulphuris simplex, P. L. 1745.
Great care must be talion that the vesset be sus cientirlarge to contain thrice the bulla of the ingredients, and that the heat be not raised higher than iust to malae the ollbubble, sor without sucti care the mixture Will swell, bollover, and infame. The Edilaburgh Pharmacopoeia direct only half this proportion os sulphur.