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retori; the colit then produced by the solution of the salt willcounieraci the heat produced by the stat ing of the lime, anda charge So made Will be manageable untii the receiver is fitted on, and the heat of the sand bath applied ; this heat nee lnot be greater than 300', and should be very cautio asty and flowly rat sed, to prevent the rapid ebullition and expansionduring the extrication os gas Dom a charge of such densi ty: and for the sanae reason a large retori is directed. The ammonia rises immediately in the forna of gas, and a portion of the water is theresere placed in a siluation to condense it; in the subsequent stages Water Will arise Dona the charge in theretort. The third vesset directed in the formula, may beeither a common holite fitting moderate ly, for no great pressure is necessu , to a straight iube issuing Dona thebottona of the receiver, and dipping below the su ace of the water it contains, or Woulla's apparatus may be used; butwith moderate attention the simpler means will ans ver bellerperhaps than the more complex. This process is, I belleve, osten persormed upon a large scale in an iron retori, which does no injury to the preparation, whilst a glass one Willos course be brohen. In either case the receiving botile must be hept cold by wet cloths or ice, for the lower thetemperature of the Water the greater quantity of ammonialgas Will it condense, and the condensation is accompanted by an increase of iis heat. Is two botiles, each containing half the quantity of Water directed, be used, they Will be most manageable, as they may be changed alternately, so as to Pre-vent ei ther frona being overtieated, and the contents of both may bc mixed together at last. This preparation is colour-leSs and transparent, with a strong peculiar, characteris csmeli; it paris With iis ammonia in the forin os gas is healedio l30', and requires to be hept with a cautious exclusion ofatmospheric air, to the carbonic acid of whicli it rea lilyia es: on this laiter account the propriety of heeping it in
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smali botiles instead os a large one has been suggested. Water saturaled with ammonial gas has a less specific gravi ty than common water; and the solio ing useful Table, indicative of the quantity of ammonia contained in solutions according totheir specific gravity, is taken Dom Mr. Davy.
Kali Metatum, P. L. II 8 I. Sal diureticus, P. L. 1745.
over the si re, adit gradu atly us naucli more acetio acid ns may bo necessary sor persectsaturation. Let the solution he sui ther reduced to one-half by evaporation, and stratiait: then by means of a Water bath evaporate
it, So that ori bcing removed si oui the sire itshali crystallige.
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In the former Pharmacopoeia no directions were given fortite crystalligation of this sali, but merely that iis solutionshould be evaporat ed to dryness. The crystalli Zed sali is however a more elegant and uniform preparation, and as itis made by sonae chemisis upon a large scale, it is usuallysound in the shops, and it requires only to be fused to assume this appearance; the great potiat Os attention necessary is, that the heat be never Suffcient to decompose orchar the vegetable acid. Iis crystallization depentis iapontho liquefaction of the dry sali by heat, and the assumptionos a regular form as it coois, rather than on separation Domiis solution in Water. From iis foliated appearance it hasbeen called Terra foliata Tartari: it has also been nam edtal Senuerti, in honour of Senneri, whom Boerhaave supposesto have been iis inventor. Lowitz has advised generally, that colouring matters should be separated si om saline substances, by an admixture of them With Deshly burni and poWdered charcoal, and, as the practice ansWers, it may beoccasionalty usesul to employ it in this preparation. Acetate os potass is white, shining, and uni ted into a mass of large plates, whicli deliquesce in the air. Water at 60' dissolvesari equat weight. It is solubie in Dur timus iis weightos aikohol. In the present preparation the athali rather pre- dominates, but not in an unpleasant degree. Is the sali becoloured, it is said that it may be rendered colourless by λ- Sion, solution in Water, fit tration, and evaporation; and that in this process carbone is separated and collected on ilia Tter.
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Tali sit, latum, P. L. I 78 I. Tartarum vitriolatum, P. L. 1765. Tartarum vitriolatum, P. L. I 720.
Take of tho Salt whicli rem atris aster thedistillation os Nitrio Acid, t vo
This sali Was prepared formerly by exposure of the residue aster the distillation os nitric acid, to a violent and continuedheat so as to drive off the superabundant sulphuric acid; than whicli the present mode is more manageable and conVenient. The concretion of the sali in the common processosten brolae the retori, and was at any rate got out of it witti dissicut ty on account of iis insolubili ty; this super sali is more solubie, and is when it is reduced to abolit the temperature of
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Tahe of the Salt which remnitas after thedistillation ol Nitrio Acid, livo
This sali is the immediate residue aster the disinlation os nitric acid, first dissolve 1 and then crystalliged; in iis coarsestate it has usually been hept by Muggisis for the use of silversmiths, and was formerly also used in pharmacyunder the litteos Sal Enixum. On crystalliging, it chiesy fixes it self to thesi de of the vesset, Dona which bed flendor Deedies Sometimes Shoot. It has a strong acid taste, and reddens vegetableblues : one part is solubie in two of water at 6O', and in tessthan an equat weight at 212', and it is not solubie in allioliol; it affords a useful means os producing the essects of sulphuricac id coinbined with those of an opening Sali, and may be e X-
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Gli fariarietatum, P. L. 178 I. Tartarum solubile, P. L. II 5.
Supertartrate of potass contains of superabundant acid, whicli is here neutralized by the addition os subca bonate os potass, and a neutral tartrate of potass is formed, the cessation os emervescence being the test os saturation. Iis crystals are laur equal-sided prisnas, terminated by tWo-
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s dest pyramids. Iis taste is somewhat bitter. One part issolubie in Dur of Water at 60', and lience, compared with thesparingly solubie super-tartrate, iis name of solubie intriar hasbeen drawn. Potass and tartaric acid have a stronger disposition to unite in the tiroportions of the super sali than of the neutral one; herace the addition os more tartaric acid formsa granular precipitate os super-sali, and so do other acids also, with any of whicli therefore it cannot be properly directed in prescription.
Tali pripparatum, P. L. t 787. Sal absinthii, Sal tartari, P. L. I 765.
Boiling Water, three pinis and a
hal f. Dissolve the potaSs in Water, and sitier: theri potir the solution into a Clean iron potniad evaporate tho Water OVer u moderat Osire, untii the liquor thi cliens: then let thesi re bo Withdra via, and stir the liquor Constantly With an iron rod untii the Sali concretes into granular CryStal S. A purer subcarbonate of Potass may heprepared in the fame manner froni Tartar, whieli must si si he burni untii it be comes
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Previ ous to the Pharmacopoeia of I745, the alsiali ne saltobtained froin the ashes of different vegetabies was supposedio differ, and a great number of preparatioris of the fame,named after the particular plant Dom Whicli they were obtained, were directed to be kept. Ordinary potass is prepared by the incineration os various vegetabies, and is denominated in commerce by the place froin whicli it is imported, as Russim, Americata, &c. The only difference Whicli respecis theptant, is in the proportion of alhali it vi et is ; this exton Messo to the severat soris of potass whicli are found in themarhet: and ali of them contain heterogeneous matters in abundance, but in different quantities; as sulphateand muriate os potass, insolubie matter, &c. The proportion os pure potass obtained froin disserent soris varies ac- cording to Variquetin Dom to The object of the present process, is to obtain the subcarbonate os potass in asussicient though it will not be complete state os purity. The
neutral salis dissolve in the water as Heli as the subcarbonate ;and in the former Pharmacopoeia enoui Water Was used seritie solutiora of both, and they were asterwards separated by crystallization, allowing the solution to cool for that purposeas soOn as a Pellicle appeared. It has been thought that this part of the process whicli is connected with sonae labour an leXpence miglit be omitted, and that the fame effect wili beproduced by using, in the sirst instance, only enough Watersor the solution of the more solubie subcarbonate. Whenthe solution has evaporat ed to abolit the consistence of Cream, the proportiora of Water Whicli remains is necessary to the composition of the crystals; the further evaporation is there- fore to be stopped by Withdrawing the fre, and the mixtureis to be stirred illi it concretes into crystalline gratias. It is matter os absolute necessit y that the iron pol should be cleariand Dee froni rust. This sali deliquesces, and theresere re
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Tartar, the other solarce frona Whicli subcarbonate os potassis obtained, consists of supertartrate os potass, mixed witti Lewer heterogeneous matters than common potass. Thisacid, like the other vegetable acidf, may be Wholly de om- sed by a strong heat, and the subcarbonate remains coloured by carbon. Trealed by the fame process as theformer, this yiet is a purer but more expensive sali, and is directed to be kept as being preserable for many processes, ora account of iis comparative purity.
Tahe of Subcarbona te of Ρotam prepared froni Tartar, a POUnd. Carbonate of Ammonia, three
Distilled Water, a Pint. IIaving previ ousty dissolved the sub carbonato os potas S in the water, add the ca bonate os ammonia; then, by means os asand bath, apply n heat of 18o for threeliours, or untii the ammonia stiali ho dri venof : lastly, set the solution by to crystallige. The rem aining solution may be evapora ted
This process was invented by Berthollet. The potasstines the carbonic acid frona the ammonia, Whicli is volatile
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and passes OT in the temperature employed; it is howeververy dissiculi to de tacti the ammonia enti rely. Potass is thus saturaled with carbonic acid, of whicli it contains doublethe quantity that the sub-sali does; it gives out this proportion on the addition os muriatic acid, and may be converted again into the sub-sali by heating it for astiori timeto redness Phil. Trans. Vol. xcviii.). It is tess nauseolis to thetaste than subcarbonate; it crystalliges, and does not deliquesce. Water at the common temperature dissolves one-fourth iis weight, and at 2I2' sive-fixilis, but this lat ter heat delaches some of the carbonic acid.
SOLUTION OF SUBCARBONATE OF POTASS.
Aqua ἐali praeparati, P. L. II 8I. Lixivium tartari, P. L. 174.3. Oleum tartari per deliquium, P. L. II20.
Dissolve the sub Carbonate of potass in the water, und ilien Stra in the solution throughP Per.
This is a more definite preparation than the aqua Eali Praeparati of the Pharmacopoeia of 1787, and it also dissem stom it: for, during the exposure necessary Dr deliquiescence in the lalter, carbonic acid as weli as moistuae