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ALKALIES AND THEIR SALI S. 81 The rem nining solution may be evaporate lin the fame manner, that Crystals may agatus orni When it is set by.
This process Was invented by Boethollet. The potasstalaes the carbonic acid Dom the ammonia, Whicli is volatile and passes OT in the temperature employed; it is hoWeververy dissiculi to delach the ammonia entirely. Potass is thus saturaled with carbonic acid, of Whicli it contains double thequantity that the sub-sali does ; it gives out this proportionon the addition os muriatic acid, and may be converted againinto the sub-sali by heating it for a stiori time to rediaess Phil. Trans. Vol. xcviii.). It is tess nauseous to the tastethan subcarbonate ; it crystalliges, and does not deliquesce, but it stili gives the alhaline green colour to vegetable blues. Water at the common temperatures dissolves about one fourth iis meight, and at et 2' sive-fixilis, but this laiter heat delaches sonae of the carbonic acid.
Gli pseparatum, P. L. II 87. Sal absinthii, Sal tartari, P. L. II45.
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ALKALIES AND THEIR SALI S. Dissolve the potass in Water, and siter; then potir the solution into a Clean iron pot
and evaporate the Wnter over a moderat C
hre, untii the liquor thichens : then let the
sire he withdrawn, and stir the liquor Constantly With an iron rod untii the sali con- Cretes into granular CryStal S. A purer sub carbonate os potass may be prepared in the fame manner frona Tartur,
Previous to the Pharmacopoeia of II45, the alhaline saltobtained Dom the ashes of different vegetabies Was supposedio differ, and a great number of preparations of the fame,named after the particular plant frona Whicli they were obtained, were directed to be hept. Ordinary potass is prepared by the incineration of various vegetabies, and is denominated 'ia commerce by the place Dom Whicli it is imported, as Russian, American, &c. The only difference Whicli respecis theptant, is in the proportion os aikali it yields; this extendsalso 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 sulphate and muriate os potass, insolubie matter, &c. The proportion os pure potass obtained stom different soris varies according to, auquel in Dom 'I4 to 38. The object of the presentProcess, is to obtain the subcarbonate os potass in a sussicient though it will not be complete state os purity. The neutralsalis dissolve in the water as weli as the subcarbonate; and
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in the former Pharmacopoeia enotagh Water Was used for thesolution os both, and they Were asterWards separated by crystalligation, 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 some labour andeXpense might be omitted, and that the fame effect wili ho produced by using , in the first instance, only enough water
for the solution of the more solubie subcarbonate. Whenthe solution has evaporated to about the consistence of cream, the proportion Os water Whicli remalias is necessary to the composition of the crystals ; the further evaporation is there-
fore to be stopped by Withdra ing the sire, and the mixtureis to be stirred illi it concretes into crystalline gratias. It is matter os absolute necessity that the iron pol should be cleanand Dee frona rust. This sali deliquesces, and there re requires to be Eept in stopped botiles. In iis ordinary state in the shops it is called Peari Ashes.
Tartar, the other source Dom Whicli subcarbonate of potassis obtained, consists of supertartrate os potass, mixed withfeWer heterogeneous matters than common potass. Thisacid, like the other vegetable acidf, may be Wholly decomposed by a strong heat, and the subcarbonate remalias coloured by carbon. Trealed by the Same process as the former, thisyields a purer but more expensive sali, and is directed to bekept as being preferable for many processes, on account of itScomparatiVe purity. From the substance frona whicli it is
prepared, it has derived the name, Whicli is stili in commonuse, of Salt of Tartar.
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Rufi vitriolatum, P. L. 1I8 . Tartarum vitriolatum, P. L. II 45. Tartarum vitriolatum, P. L. II20.
Tahe of the Salt Whicli remalias after thedistillation es Nitrio Acid, tWO
The salt was prepared formerly by exposure of the residue aster the distillation os nitric acid, to a violent and continuedheat so as to drive olf the superabundant sulphuric acta; than whicli the present mode is more manageable and convenient. The concretion of the sali in the common process
osten brolae the retori, and was at any rate got out of it with dissicut ty on account of iis insolubility; this super sali is more solubie, and is When it is reduced to about the temperature of212', after the distillation of the acid, bolling water bepoured on, it may be eastly dissolVed, and the retori saxed.
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Speciscum purgans, Nitrum sxum, Arcanum duplicatum, Salde Duobus, Sal pol chrest, tala.
Tahe of the Salt whieli remains aster thedistillation os Nitrio Acid, t o
Boiling Water, solar Pound S. Mix them together so that the sali may be dissolved, and strain the solution: then bollit down to half, and set it by that crystals may sortia. Having poured a Way the Water, dry the crystals upon bibulo uS Paper.
This sali is the immediate residue after the distillation os nitric acid, frst dissolved and then crystallized ; in iis coarse
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state it has usually been hept by druggisis for the use of silversmittis, and was formerly also Used in pharmacy under thetille of Sal Enixum. On crystallia ing, it chiesy saxes itselfio the fide of the vesset, Dona Which bed flender needies sonaetimes Shoot. Ιt has a Strong, acid, and bitteristi iaste, and reddens vegetable blues: One part is solubie in two ofwater at 6O', and in less than an equat weight at 2 i 2', and itis not solubie in allioliol, and effervesces With carbonates of aikalies ; it affords a useful means os producing the effecis offulphuric acid combined With those of an opening sali, and may bc exhibited at once in a solid form, an indication whichis osten destrabie. It consists of 37 paris of sulphate of potass, with 33 eXcess of acid. It has been affirmed that this sali contains a large proportion os nitrate os potass, almostas Io to 13 ; that a true supersulphate is attainable with great
difficulty; and that the superabundant acid is attached, and not chemicatly united, With it.
Gli tartarietatum, P. L. II87. Tartarum solubile, P. L. IT45.
uoi ling Water, a gallon. Dissolve the Subcarbona te of Dotas8 in
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Supertartrate of Potass contains ' 44 of superabundant acid, whicli is here neutralized by the addition os subcarbonate os potass, and a neutral tartrate os potass is formeli, the cessationos effervescence heing the test os saturation ; for this purposealso, three pounes of the supertartrate require three potandS, ur ounces, of the ordinary Subcarbonate. Iis crystals are ur equal-sided prisnas, terminated by tWo-sided pyramids. Ιts taste is somewhat bitter. One part is solubie in four ofWater at 60', and lience, compared With the spar ingly solubie supertartrate, iis name of solubis tartar has been drarun. Potass and tartaric acid have a stronger disposition to unite in the proportions of the super-sali than of the neutral one ;hence the addition os more tartariC acid fornas a granular precipitate of supersali, and so do other acids also, With any
of Whicli tuere re it cannot be properly directed in pre-
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Natron tartarigatum, P. L. 1787.
This sali consists of tartaric acid, soda and potass, the sodacombining With the superabundant acid of the super-sait: itis there re a triple sali, and it has been judged more convenient here and in some Other instances to express this difference by the adjective tartarietata, than to introducethe three Nords necessary to iis description. Iis crystals are prisms of eight or ten uiae luat fides, having their ends trun-
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cated at right angies. It is solubie illae taricate os potass, it giaste is bitter, and ii essioresces on exposura to air. Vauque-lin states, that it consists of tartrate os potasS '54, tartrate offoda - 6. Ιt has been called sali of Selantite Dom iis inventor, and also Sal Rupellensis, or Rochelle sali. No distinction was made, P. L. I 45, betWeen the salis prepared by adding soda or potass to the super-sali, and both were kept indiscriminately under the name of solubie tartar. In this, as in the sulphate os potass and many other salis, aflight exhess of alhali disposes the crystals to form more readily, and renders them more perfeci in their form.
Distilled Water, a Pint. Having previolasty dissolved the soda in
the water, add the ammonia, then by meansos a sand buth apply a heat of 18O' sor threelio urs, or untii the ammonia be dri ven Ois. Lustly, set the solution by to crystallige. There maining Solution may in the Same mann erbe evaporaled, and set by that Crystals may again forna.
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This sali bears to iis subcarbonate the fame relation that carbonate os potass does to iis subcarbonate; it is prepared in the fame Way, possesses the Same comparative aduanta geS, and contains double the paantity of carbonic acid. K lap-roth gives as iis proportions, acid 39, soda 38, water 23. The subcarbonate os ammonia is a sali eastly volatili Zed, and somewhat uncertain in iis proportions ; there is, theresere, noimpropriety in iis Use in excess, whicli is here certainlygreater than in the carbonate os potass. The crystals Will stili redden vegetable blues.
Natron praeparatum, P. L. II 8 I.
Τahe of impure Soda poWdered, a PO Ind. Boiling distilled Water, Dur pinis. Boii the soda in the water for half an hour, and stra in the solution; tet it evaporate to tWopinis, and be set by, that crystals may forni. Thro W aWay the re maining Solution.
All barilla or heip contains much heterogeneoUS matter, and the Spanish, Whicli is the purest, is to be preferred. Itis prepared by the incineration os marine planis of various Soris, and is also found native in some paris of Africa. Water dissolves the subcarbonates and other Salis, of Whicli, con-