장음표시 사용
61쪽
Volatile otis are less abundant in the producis os vegetati ii hian Some ollior principies ; th not exist indoed iuuaiy c siderable quantity but in the aromatic planis ; in sonae planis, the oti is confined to the Bowers, fruit, leaves, orbark ; gometimes it is contained in Severes of thcSe parta, aud in a fetu instances it is seund diffused throura every pari. The quantity varies, uot only according to the age, but also according to the vigour of the plant; helice it is much in
A proxima te principie, i und in som. vegetabies stinitar in
62쪽
OF THE GENERAL PRINCIPI Esmany of iis proportios to essenties Oil, is CAMPuo R. It Is a
und si iiij unci uous to the touch. It is very sparin y S01ubie in ivater, but is abinadantly solubie in alkohol, ether, and oils ; froni these solutions it is precipitaled by the addition of water. It evaporatos entirely, though slowly, at thocommon temperature of the atmosphero ; at a litier temperature, in close vegscis, it is sublimed without alteration; itis also hi ij inflammabie, the producis of the combustion be- ing carbonic acid, and a quantity of what is named camph0ric Acid. It is acted on by the more powersul acidS, Sulphurio acid charring it id forming a portion of tannia; nitric acid dissolving it, and decomposing a portion Of it, Con- Verting it into an acid ; minuatio, suoric, acetic and carbonicacid dissolving ii, without material ly changing iis comp0Si-tion, as the greater pari can be precipitaled by water. Nitricacid, repeatedly distilled froni it, converis it into a concrete acid, named camphorio acid, whicli appears to be disterent from any known acid, though it approaches in many of iis properties to the benZoiC. By peculiar arrangements, whicli impede iis volatiligation,
camplior may be decomposed by heat. et his is essected by mixing it intimately with six paris of pilue clay, mining ilio mixture into balis by the addition of water, and wheu theseare da , subjecting them to a strong heat, suddenly raised . A volatile oti, fragaeant and pungunt, os a Fiden yello V
63쪽
OF PIIARMA CEUTIC CHEMISTRY. 5 Icontaining a much largor proportion os carbon, since, by iis decomposition by heat, it is resolved principiab into char-
the properties of an essentiat oti, being odorous and pungent, volatile and inflammabie, solubie in alkohol, and precipitaledfrom it by the addition of water. Camplior is found in distinct vesicles, in the wοod id
bain of certain vegetabies. It is also contained in many e sentiat olis, as those os lavender, sage and others, suom whicliit is deposited on long Leeping. Λ substance analogous to itin many of iis propearties, is cap te of being artificiassyla ed, by the action of muriatic acid on oti os turpentine. The fame relation whicli camplior bears to the volatile, WAX seems to have to the fixed olla. This substance, thoughs med by the bee, is also a produci of vegetation; it is yielded by the leavos and fruit, aud it is sonaetimes intimate ly mlaed with the resin, gum, or extractive matter of planis. It is insolubie in water, and is solubie in very ginali quantity
the expressed olis. It inclis at a moderate heat. By distillation in close vesseis it ustords an acid. and a considerabloquantity of thick oit, a sinali quantity of charcoal bemg the
64쪽
composed. In closo vesaeis the producis of thei P decompo- uition by heat arct water, empyreumatio acetic acid, o Empyreumatio oti, und a residuum os charcoia, indicating carbon, hydrogeia, and oxygen, to be their ultimate principies. At the common temperature of theiatmosphere, they do notcombine with oxygen ; neither are they acted On by avater ;the solutions of them in alkohol are there re empi ed undertile forni of varnishes, to preserve other bodies Dom alteration by exposui e to the sir. They are dissolved by the fixedaikalis, like vise by some of the acidf, especialty the acetio:
the stronger acilis decompose them.
The eristence of resin in a veget te is discovered by infusing it in alkohol; this dissolves the resin id any is present, id it can ilion ho precipitaled froni the solution by the addition of water. Tho method of cstimating the quantio ofa estu in any vegetable, is by ascertaining the increase of weight whicli alti hol acquires hom it by digestion, or theslkohol may be evaporated by a mode te heri, and the resin obtamcd pure. Regins are in generat more active than gums, with re ectio their medicinal po vers. The purest resuas iure iudeedracarly inert, but there aro many veget tu substances Whichaci potve ut ly on the system, that appear to consist principalty of resinous' mattor, and it is in this resinous pari thattheir po vers reside. The proper solvent Or inenstrumn Ofresin is aikohol; by this it can be extracted froni Somo Ofthu other constitu ut paris of Veg tables : there are otherS, hora CVer, whicli avo solubie in the samo fluid, and theresoruit is dissiculi to obtuin the restu puro. Though resin is inso-
65쪽
, iubie by itself in ivator, γ et part of it c nu bc taken up, undLept suspended by the medium os gum.
These two principies, Gum and Resin, stare Osten naturasymixod in vegetabies, forming what aro nauaed GUM-RESINS, and SOme of the most activo articles of tho Mutoria Medicaare natural compositions of this Lind. Their chemicui pix, ferties are derived froni the two principies of Whicli theyconsist : thus, they aro only partialty solubie either in Haterox in alkohol; they are solubie in alliatine liquors ; they arensi fusible by heat, they onj sonen, and is the licat is ruised higher are decomposed, assording a litile ammonia ivitii the . usual producis, probably derived si ona the gum they contain. The proportions of gum and resin, thus mixed, are in disserent substances of this family very various ; but ili cgeneralty Such, that a mixture os equat paris of water undathohol dissolves the gum-resin. This is thela proper Solvent ; it also dissolves some other vegetable principies, pa ticularly extraci, and heuce it is the menstrum mOSi generalty used in Pharmacy to caetraci tho active matter Os vege-
BALSAM S are resinous jifices, with an intermixture generalty of essentiat Oil, and containing always a portion of the acid named Benzoic Acid. They are usualty thicla and tenacious, becoming by age concrete. They are odorous and pungent, principalty froin the essentiat od thby contain. A principio os considerable importance in iis pharmaCeutic relations, whicli is supposed to constitute tho active matteros many vegetabies, is What has hoon named by the French hemisis, by whom iis charactors woro si si estabil8hod, I XTRACT, Or Extractivo Malter. Iis leuding character is, that it is solubio oquat ly'in puro wator and in atholiol; and helice a solution os it in tho Ono suid is not precipitaled by
66쪽
resin, is indeed partly solubie in either of these fluids, but it
nover is completely so, since is it contain us much gum as
tincture it assordes is decomposed by water, and, Ciss et errare, iis watery solution is decomposed by aikohol. There is another character vhicli extractive matter is distinguishod, that of suffering decomposition when eXpoSed in a humid state to the atmospheric air; this talaes place EVCn at natural temperatures, and with stili more rapidity
the extractive matter combine and forin water, and that theineri insolubie precipitate has theresere an increased proportion of carbon. It is hom this cause apparently that themedicines powers of many vegetabies are injured by decoctionin water With the admission of air, and nos, as was at Onetinae belleved, froin the dissipation of any volatile active
operation, containing no Such principies. Ly oxynam latic acid, extraci is converted into a concrete Substance of a yellow colour, insolubie in Water, probablyfrona a similis change. It exeris assinities to argil and tometallic Oxides, and is heiace acted on by a number os metallic salts. Muriate of iiii, at thc maxinuuia of Oxidatiou
67쪽
OF PII ARMA CEU TIC CHEMISTRY. 55 precipitates it copiously, and sortiis theres e a delicato testos ii, whicli is liable however to illo fallacy that it lilio viso precipitates Some other veget te principies. uy heat it is decompoSed, astording empyrevinatio oti and acid, with a
portion os ammonia ; and ut this, as weli as in iis Spontaneous decomposition, when the re-action Of iis elements is favori
ed by humidity, it leaves as a residuunt carbonates of potasti and lime. This priyciple is supposed to he the base of what are named the Extracts of Planis ; repaxations formed by boiling Vesegetabies in Water, and evaporating the clear liquor to a thicla consistence. sis procured in this Way, it must generas have an intermixture, greater or leSS, of those principies, whicli me solubie in water ; and Dom being so liable to de composition, it must be i ured during the evaporation. Itis the basis, too, though in a similar state of intermixtureand parites decomposition, of What are named the in spissatelli uices of planis. It exists also in the Seeds, leaves, baxk, and
Though the charactors of this principie appeis to be distinctive, there is stili sonte ambiguity uesti regarii to it, particularly froin the circumstance, that these charactei S me notuniform ; a principie existing in sonae vegetabios V hicli has sonae of these distinctive properties, Without the otherS ; as,sor eXample, in Peruvian bark, the active matter of whichis rendered ineri and insolubie by decoction in Q ater, and solar has one of the peculiar propertius os extract; while ithius not the other, that os equul solubility in alkohol and Water, but is more sol le in the former than in the lalter. Nor is thero any certainty that this extractive mattor has
68쪽
os mixture, thola properties heing modised by their reciprocat action.
TANNIN. The important medicinal pr erty of astringen-cy, appeared Dom sonte chemicat iacis to he dependent in Veget te Substances on a peculiar principie, as it is discove able in thom by a chemicat test, that os striking a deep puxplo colour ivitii the salts of iron. This offect is exhibited by ullthe p0werfui vegetable astringenis, and in a degree nearly proportiunal to their astringency. A peculiar acid having been discovered to exist in these astringenis, after ardsna med Gallio Acid, it ivas supposed to be the principio onwhicli this pr0perly depentis. Dut subsequent eXperimentqliave proved, that the astringency resides in a principie of a different nature, Whicli, Dona belug the agent Chiosty concera ed in the operation os tanning, has obta ined the nante os Tan
This principio exigis in ali ille powersul vegetable astringenis ; it is extracted by maceration with vater, and is deiected in the infusion by a peculiar test, that of the animal principio denomina ted Gelatin. Is a solution os gelatin is ded to the infusion, it hecomes turbid, and a precipitate isthrown dou n, composed of the tu in and gelatin in combination. Wo have no very perfeci process sor obtaining tu in in an insulated state ; but the must simple is precipitating ithom tho infusion os a veget te astringent by lime-Water, and a terwariis submitting the computand of lime and tannis, whicli is formed, to the actiori of dilute muriatic scid, ix hichabstracis the lime, and leaves the tanniit. Tannin evapotaled froni iis solution is lo0se and Diable, of
69쪽
solution, and by some of them is decompose l. It unites With the aikalis, forming solubie compouuds ; With the earilisit fornas compounds of sparing solubilitγ ; it cxexis assinitimio the metallic oxidos, and it is principalty ironi iis actionthat infusions os vegetable astringenis produce dar coloured precipitates With metallio salis. Exposed to beat, it inbrdsau acid liquid, an Oil, and a considerable quantity of carbonic acid, leaving a spongy CharcoH. Iis action on animal gelatin is iis most important propero in relation to the object of the present ouillae, as On this probi ly depentis iis astringent pori er; it combilies with it, surining an insuli te precipitate, When e it Corrugates undrendea's more dense the animal stare of which gelatin constitutes a principat pari. It exisis in ali the po vertat veget lesstringenis, mixed with extractive matter, mucilage, gallio acid, and other principies. It has also been established, thata produci very analogous to it is cap te of heuag artificialbi Ormed, principally by the action of sulphuric and nitrio acidson vegetable substances Whicli abound in Carbonaceous matter
VEGΕΤΑΒΕΕ A cID s. The acid found in tho juice and other paris of planis, is not always the sanie. Not Iess thau sevon a citis, different froni cach other, are of vegetable origi ,- the Gallic, Oxulic, Malio, Citrio, Tartario, LenZoic, and Acuti c. To theso may bc addod the Prussic, thoughthis is more peculiarly Da med froni animal matter. GALLIc ΑcID. The existenco of this acid in somo of the more laOwerfui astringonis, particularly in the gali nut, caubo discovered by their wateo infusion reddoning the insu-sion os litinu . Is the concentrat d infusion he lost exposedio the uir sor somo monilis, this acid is deposited in tho stateos a crystallinc deposito, mixod aviti, mucous stultes, Dom
70쪽
Op THE GENERAL PRINCIPLEstimation from tho gali nut, or euon by distillation ivith M a ter, though it is doubilat whether, as procured by these orOther processes, it is altogether Dee froni tannin; that hySublimation appears to be most so. By crystalligation it is obtainta in flendor prisnis of a White colour; iis taste issovi', and it reddens the vegetable colours; it is solubie ia24 paris of cold, and in less thali 2 paris of boiling water ;it is also soli te in athohol. It suffers decomposition homheat, and the process indicates a large quantity of carbon iuiis composition. It combines with the athalis and eartiis, . and also with the metallic orides, forming with the lalter iugenerat coloured precipitates ; it is doubital, ho voveri Whether these colou S are not in a meat measu e derived homthe notion of tannin adhering to it. Gallic acid was at one time supposed to be the principieof astringency, Dom being contained in the vegetable astringenis, and giving a dard colour With the salts of iron, thechemicat test by whicli astringen appeaaes to be indicated. It is do ista, hora everi as has just been rema Led, Whetherthis tu iter properu does not arise Doni the presence Os tannis : the colour it does produco is tres deep too, than that whicli the infusion itself strikes; and the acid in iis insulat-ed state has no astringency. Tannin is much rather to heconsidered as the astringent principie, and it exiSis accord ingly ita sonae of the more potversul vegetable astringenis, in catechu or Lino, With Scarcely any trace of gallic acid.