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OF PHARMACRUTIU CHEMISTRY. 19: pungent acrid insto, is soli te in Water, crystalligabie Dom
derable specific gravity. It is, ho everi much less solubie in Water than barytes ; it requires nearly 200 paris of colli vater to dissolve it; hoding water dissolves it in much larger
living system. Α characteristic property of it is that of iis salis causing insanamabie bodios to burn with a binod-red flamo Follo ving the series of substances according to their .chemicat relations froni the metallic Oxides through the eartiis, it is termina ted by the ALMALI s. These posseSS the chemicat property most characteristic of the whole class, that os combining with acitis, neutraliZing ille acid properitos ; and they laxm compotinds, analogous in generat properties tot hose formed by the eartiis and metallic Oxides ivitii theacida. uut they display stili more enero in their chemicat
actions than the ea Pths do, una are more remoto in theiae qua lities frona the oxides of the common metals. Their tasteis extremely acrid ; thoy are highly caustio ; abundantly sol le in Water ; they cla ange the vegetabie.blue and pila Plecolours to a Meeta, the yellow to a bro via, and they combine With olis, rendering thum diffusibi e or soli te in Water. Tu oos the aikalis, Potassa and Soda, cxist natu alty in a Concretestate, but they are eastly fusod, and at a heat not cxccedingignition are volatilige l. Tho third, Ammonia, eXiStS M lienunc Ombined as a permanent gas, but it is instantly condensed by water, and absorbed by it in large quantity. Ille aikalis prosunt a singular anomaly in cliemicat consti- έi0n. At an early period of the researches of pneumatic
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OF THE GENERAL PRINCIPI Eschemist , ille decomposition os Ammonia was effecto i, aud it vas soluid to be a compound of hydrogeu and nitrogon. This suggested ille conjecture, iliat the two fixod aikalis might
be of Similar composition, containing at lea St one or other of these elements as a common principie. This conclusion Dom
od Doni illem ure substances of a metallic appe ance and luStre ; and these bases are combined with oxygen . The analogros the fixod athalis to the common metallic OXides ivas thusso far established, and the eurilis heing afterwariis foliud to
be o similar constitution, iliis analogy was extended to them, and ali those substances, distinguished by the common pr0perly of neuti aliZing aci is, appeared to he of similar consti tution. Ammonia alone remaliis inSulaled, and it presents the singularity, that while it possesses the Same generat properto , and Strictb resembles the other urialis in iis chemicat qualities, no traces of OXygen can be discovered in iis composition. The analogy there re cither fatis 1 4th regarit to it, or is it he an Oxidated substance, nitrogen or hydrogen In tho Compoliud, and contatu Oxygen as a ConStituent principie. The bases of the fixed athalis are Substances of very p culiar properties. They have the lustre, opacity, and tenaci ty of metals ; but they Want the most chatracteristic metal
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OF PIIARMA CEU TIC CHEMISTRY.uton that they contain hydrogeu, and iure metallic hydrin eis, instenil of being simple metalS. POTASH, as it ought to be named, in.conformi ty totho rese of giving a similar termination to the numes of sub stances belonging to the Samo ordeo, POTASSA, is obtainod Dona the. incineration Of vegetabies, especialty si ona the woodypari; the saline matter remaining after the wood has been biunt, conSisis pinocipuli1 of ilia S aikali, in combination w1thcarbonio acid. It is seseed froni the impurities by lixiviation ; thes acid is abstracted by the action os limo, the altialiis obtained in solution, red, by evaporation, Can be obtainedin a solid state. It is of a White colour, crystalligabie, fusil,le, and volatile at a xed heat; abundantly solubio in water, soli le also in ath ohol, pora erfully cuiastic, and possessed os est the allatiline properties in a high degre . Thoreis some uncertainty, wlaether it exist in the veget te matter om Whicli it is procured in the state in whicli it is obtamia , ou Whether iis base is a Constituent principie of that mutiater, and is o genated during the Combustion One reasonfor admitting the latior opinion, ut least iu pari, is, that thealhali cannot be extracted in so large a quantity by any other process a S by burning. ΡΟΤASSIUM, as the base of potasti has been named, is atthe temperati ive of 32ψ a solid substance, hard and britile, ofa White colour, opaque, and with tho lustre os polished sil- ver ; at 509 it hecomes sost and malle te ; ut 60ς it is in ille sorin os sinali globules, sonaculiat consi Stent ; at 70ς ithecomes more mobile and liquid ; and ut 100ς, or accordingio Cay Lussac and Thonard at I 36 Q, it is completely So. ItrequireS a temperature lauar to ni red heat to volatiliZe it. Itis littor than M ater, or even than aikohol or ether. It is
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of iis assinity to this principio, that it talius it rapidj si 0m
compo5ing wator by potassiiun, od by adding M ater to theoxide at the maximum, the excess of o gen in the lalter
and 16.63 of oxygen. Besides these, there exi sis an Oxideat the nimimum, formed by the Slow absorption os oxygen by potassium Dom atmospheric air; it is britile and inflammabie, und decomposes Waleae, attracting a Suffcient quantity of oxygen to Convert it in o potasti. SODA, or Minerat Athali, as it has been denominat ed in contradistinction to the other alliali, whicli has bestii distin guished by the epithet os vegetabie, eXisis as a constituent principio of severat saline minerat substances; but it is usuallyextracted frona the conibustion of mari ne planis. It is anforded by the combustion, combiuod with carbonio ac id, and associat d with various Other saline SuhStances, and is obtain-ed puro by the Samo generat process as that applied to pot-n h. Whuther it pre-exist in sen lautis, or Whother these, in Common ivitii land-vegetabies, ast ivd potasti in burning, whicli decomposes ille mu late of soda with ivllicli they arcimpregnated frum their siluation, So as to afford suda, has
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though possessed of the general aikalinc properties, it appears
weahor thun the othres in the affinities it exeris. Iis composition was esta lished ut an early period of . the resoarches of pneumatio chemisto, nitrogen and hydrogeii appearing, hoth Doni analytic and synthesio eXperimenis, to be iis constituent principies. When ille composition os the fixod alta ulis Was discovered, and they ivere proved to he ox des, analogy evidently suggested the conjocture, that oxygen might exist in ammonia, and Davy, frona Sonae CXperiments,ooncluded that this is tho casu. It lius since been Shewnthat these are incoi reci, and illat ammonia, by decompoSi-tion, is resolved into hydrogeii and ultrogen utone. The ana-loo in the chemicat constitution os a nonia to that of theffixed allialis, appeared to bo esta lislied in another reSpeci, that os iis having a Dictallic base BerZelius and Pontin, Swedisti chemisis, having munit, that whon the at hali is placed at the negativo wire in the galvanio circuit in contact with quiolasitver, the quici Silver increases in bulla, be comes thicla, and at lenuli a sost solid,-changes similar towhat avo produced in it by the addition of metallic matter,snd whicli can sciscely be conceived to Mise Doni any other Cause. They concluderi theresere, that in this experim ut the anmaonia had sumered decomposition, and iis motallic
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very weala amnity, and in a state os si tot condensation It stili appears, there re, that ammonia is a compound
Tho lust important class of chemicat amnis is that or
pou er of Chaning the blue, purple, and green COloui S of V getabies to a red, and that os combining with the nil alis, eartiis, and metallic oxidos, forming compotandS, in Whicli, when the combination is est lislied in the due proportion, the properties of the acid, and of the haso ivith whicli it is imited, are equully neutralized. The more powerfui acidfliave a considerable degree of caustici ; they have a Strongattraction to water, and they act With cnergy on inflammabie and metallic substanceS.
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OF ΤHE GENERAL PRINCIPLEAtermination of this name, the disserent acids which may beformed hom the base, by a disseretice in the d ree of Oxygenation, are dis singuished ; the nante terminating in the syllabie sc, when the acid is that whicli contains the largerproportion Os oxygen, and in the Syllabie Ous wheu it contatus the smulier proportion. Thus sulphur fornas livo acidS, by combining with two proportions os oxygen ; the term Sulphur is the radicat whenoe the names of these are derived, and according to the above principie, the ouo is denominated the sulphuric, the other the sulphurous acid. Where a large quantity of oxygen cari be sarther. combined with in acidivithout increastium but rather diminishing iis acid powers, the naine is expressed by pretaing the epithet ory, as oxy-
muriatic acid. Acilis have an extensive power of combination. From
many pharmaceutic operations. Those of most importauce inder this vie v are the sulphin iC, nitric, and min latio.
The SULPHURIc A cID, formed frona the fuit oxygenationos sulphur, existes combined with a Smuli quantity of water in the forni os a liquid of great deusi , and Doni this state of
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colom, and emits similar coloured dense fumes, while thoother is colosuqess : the chemicat Veiicies of both are nearly
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OF THE GENERAT PRINCIPLEspounct in xvhicli it exists, the power of acting with muchonern on inflammable bodies, in consequence of the Vel Iarge quantity of oxygen condensed in the combination, and not reta ed by any great force. hypothesis suggeSted by GV Lussac and Thenarii, with regard to the nature ofi liis acid, and these combinations of it with Oxygen, has lately been maintained by Siv H. Davy, that oxymuriatio acid, instead os being a compound of muriatio uelit anil oxygen, had beon supposed, is a sin te substance, and like Oxygen, an acidisy g element ; and that muriatio acid is a compound of it with hydrogen. This hypothesis, when propoSed, Wm supporied by no conclusive independent evidence, hut restedentia ely on those facts, whicli are explained more justly, and with more probabilitra hom ille peculiar relation os muriatios id to that portion os combined wator ich in common vitii other Aci Is it contains in iis insula ted state ; and in the progreSs of the discussion ivitii repard to it, the evidenco in Support of the common doctrine has beon extended and con
the Carbonio, Phosphoric, Eoracio, and Fluoric. CARBONIC A CID, the produci of the complete OXygenation os carbon, existing in the elastic forni, and heing absorb-ed by water Onj in sparing quet intity, lim no Veiγ active che- inices pol si , but is of importance froni existing in many natural combinations, particularly of saline and earthy substances bolonging to the Materia Medica. The characterseminent distinguishing it are iis only avea laening, not en- tiroly neutraliring the properties of the allialis, when in com