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vegetabie Juices, should be Preferred of stone Ware, orWedgwood's Ware, though practicatly no injury arises in the preparation os eXtracis stom the Use of tin evaporators heptclean for the purpose, and in their application such wili beosten found to be most especialty conVenient. Measures should be of glass, or is they be required for large quantities, of earthen are, und by no means os peWter or any metallic composition.
Fahrenheit's thermometer is commoraly employed in this country, and there re is adopted by the College. Allthermometric divisions are arbitrary, and different ones areused in different countries. It may be useful to aTx thesellowing formula: for ascertaining the corresponding degree of Fahrenheit With Reaiamur's scale, Whicli is mostly usedon the continent, and with the centigrade scale of modern
Fahrenheli divides the space belween the Deezing and botling potnt of water into 180', and considers the formeras 32', in a similar scale ascending stom et ero, so that hisboiling potnt is 212. Reaumur divides the fame space into 80', and consi-
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Or the converse of these operations Wili convert Falirentieti's degrees into corresponding ones of either of the other scales. Two definitions os temperature are also assumed withsumcient accuracy for practical use, and it Would be a very destrable thing is we could farther approximate to precision, in describing or regulating the higher degrees of heat in the application os naked fres, upon the uniformity of whichthe poWers of some of the most active medicines considerably depend. This may be imperfectly done by attending to the forin and sige of the furnace, to the quantityos air admitted, to the fige and nature of the stet employed, and to the mutuat relations of these to each other; and, aboveati, by practical experience in their management: but thereis no instrument at present in use that can be satisfactorilyand convenientir applied to this purpοse.
When we spea k of Speci sic Gravi ty, Π sup pose the substance mentioned to be of the temperature of 55 .
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stance contained in iis proper vesset is
o methods of increasing temperature are defined sorthe convenience of subsequent application, and the firstof them, the Water Bath, is extended to the application of
the fame temperature by steam, as weli as immediate imme Sion in the water, Whicli, in the preparation os various articles, especialty extracis, is much more convenient. The faci, that water, saturaled With muriate of soda, requires a higher te
perature to malae it boti, and that a beat of 23O' may bo thus occasionalty applied to substances immersed therein, Was thelaundation of the use of a sali bath in the former Pharin copoeia; but a temperature of 212' is considered fully suia ficient sor ait the preparations whicli are required, and it hasbeen judged sussicient to retain only the means os applying it. The Sand Bath may have iis heat rat sed to redness, and this is osten requisite, but the gradual transmission of heat through this medium prevenis that destruction os glassVesseis Whicli sudden changes of temperature occasion, andit is also more manageable; hence it has great advantages in the majority of processes over a naked sire. The following explanation of some other operationS Cmployed in pharmacy may not be USeleSS.
Fiat orion is a mode of separating froni liquids ibose solid
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substances whicli differ but litile in 1heir specisc gravity, and subside but flowly. For the nicer purposes of Pharmacy, bibulous paper must be used solded into a conical forna and placed within a funiael; it should be colourless, which may beoasily obtained, and theresere not the biottingi aper of ordina
use. In other preparations, linen, Woollen, Or cotton cloths
them, and whicli, theresere, are especialty applicabie to solutions of vegetable matters, and separation of them Dom their insolubie paris when required for immediate use. The strongeraclds, whicli mould destroy fltres made of animal or vege- table matter, is they require siliration, must be passed through unded glass, retained in the furanel by a fewlarger pieces firstintroduced into iis necla. For the separation os supernatant 1iquids Dom substances of greater specific gravity, and whicli readily subside to the bottom, decantation is used; Whicli means,
the heavier substance whicli has subsided to the bottona. Αυ oration is used sor separating Water Or any Other Volatilo fluid Dom those whicli are fixed in the fame degree of heat . It is there re performed by the application of heat, and it is promoted by using shalloW vesseis, and extending the sursace of the suid as much as possibie. Where it is an object to collect the volatile fluid, the operation is calleddis illation, Whicli is performed in vesseis, suited to the particular quantity and purpose V sucti as, a retori and receiver, Ora common stili. When solids are separated Dom each other,
by the greater volatilily of one in a gi ven temperature, theoperation is called sublimation. When solid substances are rendered liquid by the application of heat, it is called fusion when by the chemicat agencyos a liquid, their attraction os aggregation is destroyed, and both unite into a transparent liquor, it is called solution; this
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13last is one great object of pharmacy, and may for the most partbe assisted by moderate heat and by shaking or agitating the two together. Is the aggregation belWeen the paris of a solid substance be brohen doWn mechanically, and a liquid effused thereon be rendered turbid by suspension of the powder in it, and does not become transparent, nor the powder Iose iis solid mode opeXistence, it is called mixture. In other operations of pharmacy, dissolved substances are separated Dom their solutions by other additions made thereiband obtained in a solid state; this is called trecipitation.
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seq.): and Chemicat Substances according to the modern nomenclature ; unless it be othermise expressed. Note. I have added to this translation referetices to the volumeand genus V Milidenotas Species Plantarum, and to the plutes of ch vhich tire contained in Moodet ille's Medicat Lotany. Irae indigensus pluuis L. have also referred to Smith's Flora Britannica Lond. 1806.L and 4que qlso mur cd the quantity of isoria u. d.
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Acidum sulphuricum, Sulphuric acid.
The speciso Gravi ty isto that of distilled
Artemisia absinthium, Sp. Pl. Wil. iii. 18 4.
This proportion is alio as 37 to 20.
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Althaeae Folia & Ra dix, Althaea ossicinalis. The
Ammoniae ΜUriRS, Muriat of Ammonia.
This plant, described in the above Work tom. i. pl. 53, 54.) for the first time, was raised in the Royal Garden at Berlin, by Dr. Willdenow, Dom the see is tinen out of the Ammoniacum of the shops, whicli, it is Uell known, ostencontains them. The author declares himself to be satissed, that this drug is produced by Heracleum gi miserum, thoughhe has not been successsul in his endeavours to procure itfrom the planis raised at Berlin.