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This sali is now for the frst time directed to bo prepared; in
the former Pharmacopoeia, the ordinary sali of commerce Wasmerely purified by solutionand crystallization. That sali is ne-Ver pure, but contains iron, copperi and ali ille lead, est of whichmay however be separated by apiece of metallic Zinc immersed in the solution, Whicli, by iis stronger assini ty to sulphuric acid, will disto lge these other metals. It has iapon the whole, however, been judged to be more advantageous and certain, and not so much more expensive as to be an object os importance on that account, to direct the mode of iis preparation. Perhaps the best method to procure the metal, whicli possesses some malleabili ty, in pieces smali enough to be east lyacted upora by the acid, is, to divide the ginc by pouring it
when melied into Water. Sulphate of Zinc crystalliges by evaporation in seu Sided pristias terminated by four-sided pyramids. It is os a transparent White colour, With a Strong metallic astringent iaste. It dissolves in two and a half paris ofwater at 6O', and in much less of boiling Water. It is notsolubie in alcohol. It consists of oxyd 20, acid 40, Water60, and is exposed to air losus a smali portion of the lalterand rather emoresces. Some chemisis have latetv consider-ed ii as a supersulphate.
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lected annually, and is they have been Leptfor a longer period, be thrown aWay as unfit
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apertures, and after variis through ahair one: then evaporate the wator hy a Water bathuntii the pulse acquires a proper Con Si St
Where the fruits aro ripe and si CSh, Press
The collection of vegetabies, in generat, is not the immediate province of the apothecary; but With respect to indigenous planis, the direction os circumstances relative to their periods of perfection, modes of preservations and botanical Characters, comes under his superintendance; and of thesehe must be able to jud ge When they are offered to him bycollectors. A fuller statement is there re introduced than was formerly given, and it is much to be wished that an attention to it Was extended to those of our colonies abroad, whicli furnish articles of Materia Medica, as there is reasonto hope that the supply of our markets Would then be more uniform in quality than it is at present. It is necessary that vegetable matters should be dried as qui chly as possibie, providod the heat applied be not so great as to destroy their colour, and sor Whicli purpose exposure to a temperature of 10O' is
fully sussicient; it is best applied by the artificiat heat of stoves, or a heated room, in whicli the influence of light is avoided.
For the fame reasons their continuance in heaps et therbefore or When drying, is to be avoided, hecause those whichare moisi and of sost texture, as leaves and herbs, Soon runinto fermentation, especialty in Warin Weather, as is Very
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of those vegetable matters which have been hept longer thana year, is intended to guard against the probability of destruction by insecis, as weli as the necessary loss of the more volatile paris of planis. When paris of planis are dried, although they are ultimately to be used in poWder, It is beller that they be hept Whole, and in sinali quantities, and poWdered as occasion requires; coated or green glass botiles Whicli preclude the agency of light, and stopped close, so asto prevent the accession of moi Sture, answer practi catly to agreat degree of perfection. Γhe Squill Mot, after it is driod, ought to be Diable, and stili to retain iis original charactersos bitterness and acrimony. The preparation of the Cassiapti rematris as before; and there is this advantage in nothoi ling it, as is somelimes done, that when it is boli sed, themucilage of the seeds is also dissolved and intermixed with
whicli latior is effected by drying it in the
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however, they appear to be impure, boli themin mater untii they Sosten, and press themthrough a hem pen cloth; then set them hy, that the reSinous part may SubSide. Ρour offand evaporate the Supernatant Solution by a vater bath, and toWards the end of the in- spissation mix intimately the resinous partivitii the gummy. The Gum-restiis, Whicli meli ea Sily, maybe purified by putting them into an ox blad-der and holding them in botling water, tantilthey hecome Sosi enough to he separate lsrom their impurities by pressure through ahem pen Cloth. Dissolve St ar Balsam in rectified spirit, and strain the solution: then distit over thespirit in a gentila heat untii the balsam has
acquired a proper ConsiSten CC.
Greater stress is nom laid than hereto re upon the caresulselection and purity of the gum-resins, and that they be obtained in such a state as to require no artificiat process fortheir purification, excepting, indeed, those Whicli are to beapplied to the coarser purpose of external use, and, sor this reason, the strained articles mill be Dund to he directed tobe employed in making plasters, &c. A bladder is mentionedsor straining the Galbanum, but When the quantity to be pre-
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155 pared is large, a canuas bag is pro rabie. With opium these observations hecome more particularly necessa , because it is intended to be used in iis crude state, without any previous preparation, by solution in recticted spirit and evaporation, as in the sormer Opium purifcatum.
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Oleum amygdalae, P. L. I 787. Oleum amygdalarum, P. L. 1745. Oleum amygdalarum dulcium et amararum, P. L. 1720.
Three fixed olis are here directed to be prepared by expressiori, and another, Olive Oil, is hept as an artiese of Materia Medica. Their generat characters are liquidity in moderate temperatUres, UnctuoSity, Deedom Dom smeli andiaste is fresti and pure, and combustibili ty. They are lighter than water, and insolubie in Water or aikohol. They readi tyunite with aikalies forming soaps; they do not boli untii theyliave attained a temperature of about 6OO'; is exposed tooxygen gas, Or common air, they combine With oxygen, and
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gradually become more dense and visci d. Some of them,as linseed oti, retain their transparency, and are called dryingolis; others becoming opaque, as almond oti, are called fatolis. One generat circumstance guar ted against in the preparation of these olis for medicat purposes, is the application ofiteat, by whicli a larger quantity of Oil may indeed he obtained, but after Whicli it is more apt to become rancid ; hence thestress Whicli is laid upon What is called c d raetoing. Theyare ali more frequently prepared upon the great scale by manufacturers, than for the sole use of apothecaries, and there- fore require more attention to their purity and characters.
Almond oti is the fame whether obtained frona the bitteror SWeet variety, notae of the peculiar principio contained in
the former being solubie in oti, or passing through With it, nordoes the quality of the od appear in faci to be influenced by tho
presence of the externat coat. For medicat use however thesweet almond is commonly preferred. It is of so much consequence in every part of the process to avoid increased temperature, that the longer immersion of the almonds in coldWater for the separation of the externat coat whicli has been
judged proper is preferable to the m6re immediate effeci, whicli is produced by their immersion in hol. It is indeed a
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Oleum e seminibus lini, P. L. II 87. Oleum lini, P. L. 17 5.
Brui se common Linseed: then expres S theoit without any application of heat.
Oleum e seminibus ricini, P. L. 1787.
Bruise Castor Seeds, previ ousty deprivedos their externat coat; thera expreSs the ollWithout any application of heat.
With respect to castor oti, the College lias conceded toxenerat convenience and practice in alloWing the use of as an inportia article, as weli as directing 1is eXpressionfrom the seeds in this country, Which is done y Veryse apothecaries. When it can be obtained, the oi sprepared, whicli is milder in iis taste, and eosty in Trtive in iis purgative effecis, is to be preferred; and is the im