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Decoctum hellebori albi, P. L. I 787.
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In the preparation os ali the CX traCis, evaporate the Water 88 spee lily as poS8ible, in abroad shallo v disti by means of a Water bath, untii they have acquired a ConSi Sten CO Pro- per for mali ing pilis, and to vards the end of the inspissation constantly stir them With a
sinali quantity of recti sed spirit.
The generic term Extraci is used pharmaceuticalty in aneXtensiVe Sense, and compriges ali those preparations Domvegetabies Whicli are separabie by the agency of various liquids, and asterWards obtained frona such solutions, in a solidstate, by evaporation of the menstruum : it includes also those substances whicli are held in solution by the natural juices offresti planis, as weli as thoge to which some menstruum is added at the time os preparation. NoW, these solubie matters are Various and mostly complicated, chemicat accuracythereiare is not to be looked for in the application of the term. Chemisis, however, have confined this name to one
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peculiar modification os vegetable matter, Whicli they have called Extractive, or Extraci, or Extractive Principie, and asthis forins one of the chies constituent paris of common EX-tracis, and possesses certa in desinite characters, it will be pro- per to mention such of them as may influence iis Pharmaceutical relations. The Extractive Principie has a Strong taste,
differing in different planis: it is solubie in mater, and iis solution speedily runs into a state os putrefaction, by whicli itis destroyed. Repeated evaporations and solutions render itat last insolubie, in consequence of iis combination mittioXygen Dom the atmosphere during these processes. It is solubie in alcohol. but insolubie in ether. It unites With alia mine, and is boiled with neutral salis thereos, precipitates them. It precipitates With strong acidf, and with the oxydsfrona solutions of most metallic salis, especialty muriate oflin. Ιt readi ly unites with aikalies, and fornas compotandsmitti them Whicli are solubie in Water. No pari, hoWeVer, of this subject has been hitherio sufficiently examined. The generat rules for the preparation of EXtracis, Whicli are givenin the texi, require minute and accurate attention, more particularly in the immediate evaporation of the solution, Whether prepared by expression or decoction, in the manner asweli as the degree of heat by Whicli it is performed, and the promotiora os it by changing the surisce by constant stirringwhen the liquor begins to thichen, and even by directing astrong current of air over iis furface, is it cara convenientlybe dono. It is impossibi e to regulate this temperature ΟVera naked fre, Or, is it be used, to prevent the extraci Domburning ; the use of a water bath is there re absolutely necessary, and not to be dispensed with, and the beauty and precision os extracts so prepared will demonstrate their superiority. I have on this account not judged ii superfluous, in order to en rce this strongly, and to fhoW ho it may beconducted conveniently, to give a shetch of a modification of
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the common tin sau pan whicli Ι derised for the use of st. Bartholomew's Hospital, and whicli, Dom iis simplicity and facility os application, must talae aWay ali eXcuse DOm those who have employed naked fres for this purpose upon a smaliscale. I am glad to be able to say, that much more attentionis pald to their preparation by the water bath at present, than hereto re. For this mode of preparation, volatile and aromatic Substances are Unfit, and the clarification or defaecationos the liquor is, in almost every instance, improper . A smali portion os rectified spirit is added to the soster extracis to preserve them Dom mucor. The consistence of extracis is important; it should be such as to retain the round form os apill without any addition os poWder. They are usualty too sost, and the temptation is considerable to those Who prepare them for sale in a large Way, not to evaporate them to the properconsistence. The omissions Dom the former Pharmacopoeia are, Extractum cacuminis Genistae, Butae, Sabinae, Cascarillae, Sennae, and Succus Baccae Sambuci spissatus. The additions to the present are, Extractum Aconiti, Belladonnae, Aloes,
Colocynthidis, Humuli, Uyoscyami, Opii, Rhei, Sarsaparillae,
Tahe of Aconite Leaves fresh, a POUnd. Bruis e them in a stone mortar, Sprint lingon a littJe Water; then press out the juice,
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and , Without any Separation Os the Sediment evaporate it to a Pro Per Consi StenCC.
This, and the Extracta Belladonnae, Conii, and FIyoscyami Would, in the language of the Pharmacopoeia os l78I, have been called in spissated juices, Sucet spissati and theyare prepared according to one common process. The teX- ture of the plant is first destroyed by bruising, iis juice is thenexpressed, and reduced by evaporation to a proper consi St- ence. Different modes of preparing these eXtracis have beenu sed, ali of which were considered When the present directions Were adopted. Some potar off the clear liquor Dom thegreen seculent matter Whicli subsides when the juice is heat-ed, and evaporating it by itself, mix the two together after the liquor has acquired the consistence of syrup. Otherscarry on the evaporation of the whole only untii it hecomes of the thichness of syrup, and then give it a pitular consist- ence, by the addition os poWder of the leaves. These extracis ali possess narcotic properties, and require caution andattention in their exhibition, though upon the whole, and Bom tolerably large experience, Ι am convinced that in common practice they are Under-dosed rather than the contrary, and that to this circumstance is to be ascribed their frequentsellure os effeci.
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-Water Will dissolve about th of common aloe accordingto Neuman, and the gummy extraci prepared Dom it purges equalty Well, and is tess heating, and more gratesul than theusual form in which it is miXed with resin. Iis solutionmay be accelerated by previousty triturating, and thus dividing the aloe With clean white Sand, as is directed in the inum aloes. As the ordinary aloe is in the Materia Μedica called Extractum, some additionat term feemed necessaryto distinguish this preparation, and purificatum feems to besusscient for the Pu Ose.
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Extractum Chamoemeli, P. L. 1787.
Boii down to four pinis, and strain thesolution while it is hol, then evaporate it to
The essentiat oti is volatile, and passes over in the heatemployed, and only a bitter extraci remains, Without the peculiar smeli os the plant.
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EXTRACI S. on a littio mater: then press out the juice, and , Without any separation of the sediment, evaporate it to a proper ConSiStenCC.
Extractum Cinchonae M cum Resina, P. L. 1787. Extractum Corticis Peruviani, P. L. I 745.
By this process the whole effective part Os bark is sepa-
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229rated Dom the ineri Woody pari, Whicli asterWards yieliis nothing farther either to Water or spirit. It is useless tohoil the water upon the bark after it is saturaled with thesolubie paris and can dissolve no more, and most probablyeacti subsequent additi0n of Water, after the first, may require for sucti effect to be longer continued than the preceding one; the decoction there re is ordered for a lesstime than in the Pharmacopoeia of 1787. For the chemicat relations os bark, the student in Ρharmacy ought to consultthe analysis of the St. Domingo bark by Fourcron A. C. v. 8,) and another by Vauquelin on the chemicat properties of barks in generat, s A. C. v. 59. Sir Iolin Pringle reporis, Bom his experimenis, that the extraci is not of equat effica-cy, quantity sex quantity, With the simple poWder.
lacerate sor four days, and stra in . Distiline tinctum in the beat of a Water bathuntii the extraci has acquired a PrOPer Con
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This is considered by many as much more gratesul to the stomach, Whilst at the fame time it produces the effects of hark in substance, especialty in preVenting the recurrence Offome periodicat diseases, and by the distillation directed it is intended to collect and preserve the spirit Whicli passes Over. It is a much more inicient preparation than the former.
II 20, that extracts may be prepared Dom any SUbstance SO-lubie in a menstruum, this active purgative extraci, Whicli is Usesul in so many and various combinations, of whicli indeed the Commonly received compound formula scarcely admits,