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nating thum, but simply by entering into combination withthem ; nor are these combinations comparatively of muchimportance. PHOSPHOROUS A cID, in Whicli the proportionos oxygon. is smasser, is stili tess important. Eo RACIc AcID exisis in the concrete forna, and iis cli micat action is comparativeb ive . So po verses is the an
huse of the acid combined witti a portion os potasti, sol med by the Oxygenation of the potassium. The experiments of Cay Lussac and Thenard have i hewn, that the acid, in thostate to whicli these observations appj, holds dissolved a IUrtion os silicuous earth, dorived either si Oin the maturials
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OP THE GENERAL PRINCIPI Esnom Whicli it is procured, or Dona the oris vcsseis in the process is persorinud ; und this Silex haes a very important influenco on iis properties. When the acid is procured Dee froni silex, it existου in the liquid state at the temper ture of 60ς ; but it evaporates rapidly, and fornas dense va-Ρoura ivben exposed to the air; and the contact os silex causes it instanti, to assume the gaseous forni ; it combines with water V ith a hissing noise, und the production of much
tinguished by the energy of iis action on animal matter, instantly destroying it, so that a drop of it ullo Ved to suli onthe flain, erodes it villi Severe pana, and produces deop-Sealedulceration. This acid fornas, with the horacic, a com-90 md acili, the Flu -boric, whicli is uiso distinguished by very poculiar properties, particularly by iis strong attractionto water, anil also by iis very powersul action ou veget leniad animal mattem There is a series of acids with compound bases, derived om the vegetable and animal system; but those of thementilled to notice Will he hest considered with the classos oξ substancos With whicli they a re more strictly connected.
The acilis coniuine with the assialis, the earths, and the. metallio ovides ; and when the combination is est listed in the due proportion, the chemicat properties of the acid, and of the haso with whicli it is united, are mutuatly neutraliZed.
an order os clienaical agenis, they are distinguished by certain Common properi ies. They can ulways bE obtained iuthe solid state: they aro generally, though not universat lysolubie in xuater ; isose os illum whicli are solubie, are Ca-pable of assuming a crystalliue forna, the forni being very differcnt in different salis. Thoso whicli crystallige Dominesv aqueous Solution, always retulia a quantity of Water iu
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combination, essentiat to the crystal, and there re namodihoir Water os crystalligation. When heated, ille inci caseos temperaturo is osten sufficient to en te this water to dissolve the real saline matter : this is named ille avatery fusion of salis; as it evaporates, the Sest hecomes Concrete,
and, by a sarther increase of heat, is either fused or decomposed. The term Neutral Sali is somelimes vestricted tot hose of whicli the aikalis are the bases : those formed Domthe eartiis are named Earthy Salis ; and those froin the me talltc oxides, Metallic Salis. The nomenclature of ille whole series is in the modern chemicat language simple, and, at therame time, Systematic and precise. They are formed intogenera and Species, according to the acidf, and the bases of whicli they are composed ; the nante of the genus is derived Doni that of the acid, the nante of the species Boin that. ortho baso th whicli the acid is unito l. Thus est the salis med froni sulphurio acid are considered as Constitutivg one genus, and are named Sulphates ; and the name of each species is expressed, by adding the name of the base, as Sul-phate of Soda, Sulphate- of Lime, Sulphate of Iron, &c. I ho acid whicli sulphur forins in a dimerent degree of oxygenation, the Sulphurous, sornas a different ordex os salis ;theso arc named Sulphites ; and in like mainter ive have Nitrates and Nitrites, Phosphates and Phosphites, &c. Those
cipie forming the genus, these compounds are distinguishodis prefixing to tho usual nante the epithet stuper, When thea id is predominant, and the opithet sub xvhen it is deficient,
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tua te of Potaesti' and Soda- Thus, by this simple system, a sucili ty of nomenclature is amorded ; the whole is unis orna, and the memory is aided, by the name potiating out the na- ture of the sali ; iis adoption in Pharmacy is there re animportant improvement, compared with the arbitrary and
Sci fax tho chemicat analysis of organiZed substances cou- nocted with tho Materia Medica has been the subject of consideration. It remaliis to tine notice of the analysis of those belonging to the vegetable and animes Mugdonis, a subjectos naucli importance, particularly us it relates to the vegeia hic part of the Iateria Medica, and whicli, froni this importance, as Heli RS Dom the native of the substances themia gelves, loquii QS to be con Sidered with more minute delatis. These two classes os hodies are distinguished by very obviolis Chomicat CharaoterS. In unorganiZea substances, illopi incipi6s are se x, aud axe Combined generalty in very simple states Os uni an ; their analysis Cau be executed with accu aeacy ; exen the proportionS of their principies can be deter termined with precision, and they can be again combined solis to Di in the decomposed substance, thus confirming the unalysis by synthesis. But, With xegard to the producis ofornauigation, while the CompoSitioia, So far as it relates totho ultimato elemenis, is more uniform, it is, with regard toti Q modus in udiich they are iniited, much more complicate l. I hey consist os a law common principies ; but theSe, lare- sented to cach othur in the vesseis of the organic bellam ha ebeen placed under circumstatices indefinitelae varied, and wlfici, uri can verr imperfecti' imitate. Combinations of
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Ille sanae elements are formod, there ire, greatly cliverSised, und properties aro derived froin disseretices of pr0portions, or modes of union extremely minese. Hence their accurate
Φalysis is executed with dissiculty, a dissiculty increased
by the circumstance, that these elements having Strong mutuat assinities, cannot in generat he obtained insulated, but vhen the compound is decomposed inter into ne v combin iions, ii te to bo rivdilied by slight variations os circum-εtances ; the propoletioris there re can seldom bo det mined vitii accuracy, the modes of union in generat remain unknown, and the confirmation by synthesis is entirely precluded. Another character distinguishes these t- classes. The composition os unorganiged hodies being more simple, is notso liable to bo subverted ; theis constituent principies heingseu , thoir assinities operate With move force, and the com hination is more permanent. That of organiged hodies he . ing m e complicated, has characters preciSely the reV SC. Composed always of severat elemenis, the assinities are morenicely, usted, and are theresere more eastly niodified ; and their principies having tondeiicies to enter into numerotis fornis of combination, si tot variations of circumstanceS Subvert the equilibrium. Heiace the susceptibility os decompo
i0 the investigati0n of the proximato pruicipies of wllicli ili
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31 OF THE GENERAL PRINCIPI EsIt is soldoin that a vegetable substauco is homogeneous. I lie seed, sor example, the Hain, or the leaves of a plant, is not of one uniform Composition, but consisis os various prOXimate principies in a state os mixture, or os sitit combinotion, and capable of heing easib separated froni euch other. Νow, these are osten connected with their medicinat vir tues ; the vilatiae residing perhaps not in the entire substanco
of the leas, bark, or feed, but in a principio capa te os beingseparated, and whicli nam frequently bo employed in iis insulated state. Helico the imporiance of the analysis of the vegetable substances belonging to the Materia Medica, solar as relates to their proximate principies ; the knowledgo it conveys enabling us to employ them ivitii more discrimination, and to submit them to the proper pharinaceutic treat-ment. An enumeration of their proximate principies, and more particularly of thoso on whicli their medicinal po vors depenti, accordin y Mways enters into their description asarticles of the Materia Medica. This analysis is expcuted in various modes, ad ted to particular cases, according to the principies which the v
Sometimes it is essected meresyiby heat. The temperature cannot in deed be elevated very high, as then the proximate principies of the vegetable would be themselvos decomposed, and their elements brought into ne v combinations. Cut at a lient comparatively moderate, as that os bolling water, this d0es not happen ; and at this temperature severat of these principies, such as essentiat oti, Camplior, and sumeo: hors n0t very weli desinod, are volatiliZod without de omposition, and of coui se can be obtained pure.
Tlio action os disterent solvenis is of more ostensive uso in conducting the vegetable analysis. Water dissolves severat Uf their component principies, Sucii aS giun and CXtPaC-
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io dissolve them more completesy; but Some of them are aptio be volatiliaed, and others altered in composition, especiallyis the atmospheric air is not excluded. of the substances whicli the water holds dissolved, pari are Separa ted as 1lcoias; the gum can be precipitaled by eskοhol; the saline substances may be crystalliZed, or Can be discovered by ev Porating the solution to dryness, and exposing the mass tofuch a heat as will destroy the inflammabie paris ; tanninand some others are detected by thela chemicat tests. Allioliol is unother agent of much importance in executing e vegetable analysis. It dissolves the resin, balsam, cam phor, and essentiat oil: these solutions are decomposed by avater, each Substance being separated, and discemiblo bylas peculiar qualities. Eques paris of aikohol and water, orproof spirit as it is named, is also osten employed as a solvent in the analysis of vegetabies. Ether dissolves nearly the fame principies as aikohol. And the acidf, aikalis, and solubie eartiis, are Sometimes of utility as re-agenis, in potiat-ing out the. existence of peculiar principies. Lastly, in the analysis os vinet les, we avo osten able toprocure severat of their proximate principies, by mcchanicalmeans, particularly by expression . Sometimes too, thesexude spontaneousty irona the gro ving veget te, OP are obtained by it froni incisions made in the branches or trimi . Aiter We have discovered tho proximato principies of Apiant, or of any part os it, the nexi step is to ascortata theircumposition. This is an investigation attended, howeve
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ος THE GENERAL PIUNCIPI ESariSing Dona a complicatod analysis, and incapable of hein Confirmed by tho stu er test whicli synthesis amor is . The composition of these substauces With respuot to theiridi ima te pi incipies is nearly unimi m. All of them conisi carbon and hydrogeia, generat ly is not invariably united wim
OXygen : some farther contain nitrogen and phosphorus; and in others severat of the metias, particularly tiron and man- arae, exist . Lime, too, and the two sxed aria is, eitherpi e Or more commonb in combination with some of thoacitis, are not uiasi equently constituents of vegetable matter. These lalter substances, hora ever, are seldom in any Considerable proportion ; nor in generat do they appear to modi sy-muta the properties of the substances in Whicli they exist Nitrogen, and perhaps time, When present, appear to have themost important insuetice, and with the exception of the se v
sa id, that the vegetable proximate principies consist of ca hon, hydrogen and oxygen ; the differences in thei P properties being produced by differenoes in the proportions of these principies, and of the modes in v hicli they are eombined. That a differetice in the proportions of thes' elements maygive rise to ille differetices in the properties of the com- pomads whicli they sortia, cannot be doubted; since in many other cuses of chemicat combinations, where there is no dinsculty in the analysis, differetices equalty important and wellmai Led ure produced by this cause. In vegetable substances we accordin y can Osten trace this as the cause, Without be-ing able to potui out any othcr. Thus, fixed and volatileoils have properties in many respecis dissimilar : by analysis both ure foliud to consist of cathon und hydrogeia, united indifferent proportions, tho volatile otis having more hydrogentu proportion to the carbon thali the si cit, have ; this is acuti se Suilicibi, to account for the dis eretice in their propor-
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etles; and it accords susticiently With that differetice, lar hydrogeu being a substance of great rarity aud volatilily, those comp0unds in Whicli it predominates, us ether, ait Ohol audoilios, are in gentires light and volatile. The greater Volatilily, illexesore, of the essentiat, compared with the fixodolis, may be ascribuit to iis pavedominance. Iii other cases, it is probable that the mode in Q hicli thec OnStituent punicipies of these substances are imited, is thecause of the differetice in their qualities. This is indoed a cause ivllicli can he but imperfectly investigated, cithor byanalysis Or synthesis; but it is conceivable re priori, auds ciently confirmed by chemicat facis, that a disseretice in
ille mode of union may give rise to very important diversities of properties. Is a conapo d, sor example, consist of three elemenis, these may be united in tu o modes. Theti attractions may be reciprocatly balanced, and they may form at is named, in Strict proprieto, a ternary Combination ;Or, Dona a Variation in the circuitistances under Whicli theimion has been effected, or a differetice in the streiigili oftheir attractive powers, two of them may be Combined, and tho compo und thus formed may exert an attraction to thethird principie, unite with it, and forin a alew Substanco. The compounds resulting Dona these different modes of com-hinatiou, though coimposed of the Samo princitates, unite lyexhaps even in the fame proportions, would stili have pro-pua 'ties different Doni each other. Stili greater diversities vili be produced whoro the olements are more numerous, and the p0SSible modes of union ait of course more diversisse l. And when de consider these causos froni difforonce of proportions, and modes of combination, we Shali Scarcely be Sur-pri sed at tho number of difforent substances, immense as it vhicli nature fornas froni a sexu clementary principies..i he pr0Simate principies of vegetabies aru SOmetimes anais
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OF ΤHE GENERAL PRINCIPLES Used by dxpos e to licat: their clements enter into ne vcombinations, and Doni the nature of the producis, we dis- covev what the principies Were. 'I'hus, is the substance ex-
posed to heri yields a large quantity of auid, ive conclude
that it contatas a considerable quantity Os oxygen aS a Constituent pari. Is it inord much empyreumatio Oil, ive inferthat it contains a laa ge proportion of hydr0gen, this priH-ciple being necessary to the constitution of that produci. heu ammonia or prussio acid is umorded by this Lind 0s analysis, we conclude, for the sanae rei on, that nitrogeuhas been a constituent principie. Aud by the Samo mode are discovered the oaPths and metals Which had been present init; these remianing Rex the volatile puris have been expel- led. Lastly, froni the quantity os charcoat whicli remalas
tity of carbon whicli the vegetable Si Stance contained. Their analysis is altio effected by exposing them to heat with the access of atmospheric ait', and collecting the producis of the combustion that tines place. Fhom the natureos these producis, we can ascertain the proportions in whichthey were uni ted. Oil, lar example, when subjected to this analysis, yields nothing but carbonic acid aud water. v econclude theresere that it is composed of carbon and hydrogen, si uce these principies, united with oxygen, sol in these producis, and Since, is any other Simple substance had exist-od in the oit, it would have appeared cither pure or in Combination ivith oxygen. We caii even determine in this man-ner the proportion in Whicli the carbon und hydrogen existe lin the combination. I 0m knowing What quantity os car-hon exista in a giveu quintity of carbonio acid, and what quantity of hydiaeigen existS in a givuli quantity Os water, P ethus also disco 'er hether any oxygen had existed in the, omposition os tho oll.