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Fig. I, 2, 3, 4. These figures are given for the purpose of explaining the Water Bath, for preparing EXtracis, mentioned page 2I5: Ιt in faci requires in iis use tessattention Dom the operator than the more commonand destructive method of evaporating them imm diately over What is called a flow sire. Fig. I. A common tin vesset With a spout projecting Domits sido, through Whicli the steam may Pata, and an addition os more mater be made, When neceSSary. Fig. 2. Upper concaVe Surface of the coVer, Or e porat-ing pan, the edge of Which projects over that of the vesset. The part to contain the liquid might bemade of Wedinood ware Without dissiculty. Fig. 3. Section of the coVer, or eVaporating Pan. Fig. 4. Section os a deeper cover, or pan; to contain a larger quantity of liquor; by Whicli the first part of the process may be performed With less necessity forattention : the lalter pari, Whea it requires more Constant attention and stirxing, is best performed by
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any liquid, to the levet of the mark of the quantityrequired, and the superior end then closed by the finger, Will retain that quantity on iis removat, and thus allow of the mensuration of the smallest divisionos the wine gallon whicli is required. Is is by no means intended to impeach the accuracy of these meastares, as prepared by ditarent individuatq; but itfeems right, in the first instance, to state generald, that those made under the patent of the late Μr. Lane, and sold at Apothecary's Hall, are e X tremely accurate in ali their rela
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Cong. Congius, a gallon. Cochl. Cochleare, a spoonsul. Wholesse dealers and Apothecaries buy their drugs by Avoladupois-Weight, though Troy-Weight is used for thecomposition os medicines. The relations, theresere, and the disserences Whicli exist belween the tWo, ought always
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The mensure os liquids also dissers, oneheing used for beer, and another sor Wine; ve adopi the lalter, and employ for liquid smensures Whicli are derived from the wine gallo n. The Wine gallon is desined by the statutes of the kingdom, and we divide it for medicat purposes in the solio Wing manner, ViX.
The gallon Cong. The pini The fluidounce The fluidrachm
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A most importlint change is no v frst adopted in the mensuration os liquids.and the division of the wine pini, bywhicli it is intended to introduce accuracy in the meaSurementos quantities of liquids below one drachm. For these thetable of no former Pharmacopoeia has provided, but as somo such were alWays absolutely neceSsary in datly practice, so theuncertain method os drops Was adopted and generalty received. The number os drops contained in one Auidrachm hasbeen assumed to be siXty; and taking Water ah a standard, this number, though by no means accurate, Would stili besum ciently correct for ordinary Purposes; but when other liquids of less specific gravity are used, a much larger number is required to sill the sanae measure, as of proos spirit14O drops are required to equat the bulli os si xty of water
dropped Dom the fame vesset. Is, there re, in the compositionos medicines, measures suiled to the standard of water Nereus ed occasionalty only, and it Was generalty assumed that si Xtydrops were equat to one fluidrachm, and one fluidrachin os tincture os optum Was substitutest for siXty drops prescribed,
twice the dose intended. rould be given There are further objections to the use of drops; that their bulla is influenced by the qu antitv of liquid contained in the botile fros icti theysali, hy the thichness of the lip, and even by inssqualities in thedimerent paris of the lip of the sanae botile; that volatile liquidsto whicli this mode is most commonlyapplied, are thus exposed
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filli extensive sursaces and their evaporation promoted; andon ali these accounts the adoption of Some decisive, convenient and uniform substitute became necessary. The subdivisions of the wine pint have, theresere, been eXtended to the fix-tieth part of the fluidrachin, and glass measures expressive ossuch sub-divisions have been adopted by the College. These'will be as uniform and constant as the weighis empi ed sorsolids; the accuracy of the former as weli as of the lalterbeing, of course, dependent upon precision in their construction, Whicli is not more dissiculi to be attained in onethan in the other instance. Similar latin terms and characters have been hereto re used to express the potand, ounce, and drachm os solids and liquids, and thus di erent quantities have, in faci, been expressed by the fame name; an error Whicli hecame more evident When it Was proposedio extend it stili farther, and to cad the least division ofliquids by the nanae of a gratia. This similarity has bden asource of complaint Dom the time os Galen De compos. Medicam. l. 6, 98), and, on adopting more minute divisions os liquids, the College have resolved also to adopi some arbitraryterms that might distinguisti belween them and the weightgof solids; and in those Whicli they have taken, they have,
With respect to measures of ounce and drachm, Whicli are in most common Use, been anxious to do as litile violence aspossibie to establishod habiis, consistent With the distinctionat whicli they have almed; and whicli they have also upon' the fame principies extended to the signs by Whicli they maybe designated. In our own language the pint is suffciently
distinct froin the pound, and may stili be retained as a translation of the term octarius. In the banishment hoWever ofa particular practice Dom pharmacy, the banishment of the term immediately expressing it, and forcing it upon the recollection, became also necessary; for this reason the term
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drop could not be retained to signify the si xtieth pari os assuidrachm, and the coinage of a neW term became absolutely
The college have especialty adopted the glass measures originalty invented by the late Mr. Timotis Lane, F. R. S. inwhicli the standard wine gallon of the Exchequer is dividedin 6I,140 paris, noW called minims, and whicli are applicabie Witti accuracy to the mensuration of the smallest of thesequantities. By an act of partiament, l4 Αnn, the wine gaulon is fixed at 23 I cubic inches, and the weight of the stand-ard eaechequer gallon Os water at a temperature os 63 and barometical pressure m 29,52, is 58,l76 Troy grains. It wili further be remembered, that the use of measures orWeighis made by any particular person are not insisted uponby the College; and provided they be accurate, it is of no importance Where Or hoW they are procured. Perhaps sufficient attention is scarcely paid in generat to the state of the scales and weighis: they are necessarily exposed in the shopos the Apothecary, to circumstances Under Whicli their accuracy is impatred, and they theresere require greater care.
The beam inould remain in equilibrio even is the scales bechanged, and it should turn With a very smali addition to iis weight; those uSed in the Stiops may eastly be procured soas to be influenced by Ath of a grain. I had intended to su oin to this translation a table of the relative value os drops and measure, but I found the formerso very variabie, that it could not be applicabie under any auteration Of. circum tances, and there re it Seemed beller toomit it altogether I subjoin the following table as has been done With Weights.' A useful pumphlet i*on this subject has been publisled by Mn Shutilata0rtk of Liverpsol.
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Pint. Fluidounces. Fluidrachms. Minims.
In addition to this explanation it is fui therto be observed, that in this book We desino the quantity of dry articles by eight, and that os liquids by measure, uniess it be Othe
Care is to he taken that neither Coppernor lead enter into the composition of the
ure glaged by lead are improper.
This injunction is repeated Dorn the formor Pharmacopoeia, and extended stili farther to a prohibition of those vesseis Whose furfaces are covered with a glage of lead. In many instances the reduction os substances to poWder requires mortars to be used os large siete, and Suffcient strengili tobear the application os considerable force; these Were se merly made of the composition called bell-metal, and stillheeP their place, though improperly, in many shOPS. ΜOr- tars of iron ought to be substituted for them. In the present ystem, hoWeVer, the reduction os substances to po der is Only occasionalty practised by the apothecary, and it is ms t
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commonly done iapon the large scale by drug-milis, and thoarticle is supplied to the shops in the state os poWde fitectat once for use by this division. Now this is one of the modern facilities and arrangements of trade wh: ch cannot betoo cautiousty looked after. The proprietor of the milli, perhaps, returns for a given Weight of the gross article seu fifths, talaing the disserence for the use of his machinery anclloss in the preparation. He has also the power of substituting or mixing in an inferior article Without sear os detection, Since When those externat qualities by whicli thegoodness of drugs is chiefly estimated are tost, it is very
dissiculi indoed, is not impossibie to identi se them. Anyman who occasionalty looks at the drug sales of the metropolis, Willi find very large proportions os refuse articles inhichought to be destroyed; these, nevertheless, are purchased, and under the conveniences Whicli the form os poWder gives,are osten dealt out to the consumer blended in a masterly manner, under the character os drugs of superior quali ty.
It is there re destrable that the Apothecary should poWder his own drugs; and a Iarge iron mortar, or What is stillhelter, a sinali hand-mili mill effect this in a sussicient de-gree for the consumption of any Ordinary concern, exceptingin a feW articles,'hicli are harder, and theresere more difficultly br en down. Where substances are insolubie in Water, the addition ofwater so as to form them into a paste may be usefully made, whicli is to be rubbed or levigated in a mortar illi it is suia sciently sine; this prevenis the loss and inconvenience of quantities of the siner powder being scattered about in the form os dust. The mode of separation os poWders of such substances of an equat degree of sineness Will be spolien of