A L K 



A L K 



fore, nre alkalies deprived of carbonic acid by qiiiek-lime or 

 any other matliod ; and this is tlie only llato in which, pro- 

 perly fpeaking, alkalies can be coiifidered as purt' ; though 

 even wiien they contain much of this volatile acid, th'." pecu- 

 liar qualities of the alkaline part predominate fo conlulerably 

 as to enable them to exhibit (though in a weaker degree) all 

 the chemical properties by which alkalies are characterized. 



Alkali ( Efffwefcent or Mil J), is oppofed to the Hate 

 of caufticity, and expreffes that degree of faturation with 

 carbonic acid, which, as has jufl been mentioned, diminidics, 

 but does not hipprefs, the charaAcrillic properties of the al- 

 kali. Owing to the alkali obtained from vegetable aflies 

 being always left after combullion in union with carbonic 

 acid, effervffcence "u.'i.'h adds was confidered by the older chc- 

 mifts as an effential charadler of alkalies in general, who thus 

 afcribed to a property inherent in this genus of lalts, an ap- 

 pearance which is now known to depend upon the expuHion 

 of the gafcous acid. The terms caujVtc or pure, and ejfer- 

 vjccnt or tnihl, are applied to the volatile as well as to the 

 fixed alkalies. 



Alkali ( Extemporanenus ) , is a mfid vegetable alkali, pre- 

 pared by deflagrating nitre with tartar. See Carbon at 

 of Potash, 



Alkali (Fluor), is a folution of pure Ammonia iu 

 water. 



Alkali ( Phlo^lflir), is prepared by calcining carbonated 

 potafhwith bullocks' blood or other animal matter, in which 

 procefs it unites with the Prussic acid, formed during the 

 calcination. 



Alkali fof Tartar), or Salt of Tartar, is properly a mild 

 vegetable fixed alkali, prepared by the combullion of tar- 

 tar, which yields it in great purity. The name is ufed more 

 extenlively for any pure carbonated potafli, and it is the term 

 by which this fait is more generally known in common lan- 

 guage and in medicine. 



ALKALINE EARTHS. It is by no means eafy to 

 draw the line accurately between alkahes and earths. The 

 original idea of an earth, entertained by the ancient 

 chemifts, was that of a fub (lance of confidcrable den- 

 fity, infoluble in water, without tafte, fmell, or any percep- 

 tible aAion on the organs of fenfe, entirely unfufible, and 

 fixed in the mod intenfe fire ; and, in (liort, with properties 

 as oppofite as polTible to thofe of a salt. This opinion 

 principally attached to eartii, confidered as one of the four 

 elements of which the material world was fuppofed to be 

 conllituted. The progrefs of chemical inveftigation having, 

 however, difcovered feveral ipecies of earths, which could 

 not by any means be proved to be cortipounds, in which the 

 fimple or viniverfal earth was fo difguifed as to lole fome of 

 its effential charafters, it became neceffary to alter and mo- 

 dify the original definition of an earth, and to allow to it 

 more of a faline nature. 



Some of the modern chemifts, therefore, have adopted the 

 term J'a!ijiab/f, and others aliaUiie earths, in order to allow of 

 more accuracy in fyftematical ar';angcment. By alkaline 

 earth has been meant an earth which agrees with alkali in 

 the property of folubility in water to a certain extent, and 

 thereby rendering it fapid, of changing to green certain blue 

 and red vegetable colours ; of abforbing carbonic acid with 

 c igernefs, and of poffefTing, when purt, thofe caujlic or acrid 

 quahties that fo much diitinguifh the alkalies. Magv.eja, 

 lime, barytes and Jlrontian, arc the earths which may be tenncd 

 alkaline, but the former is verj' imperfeftly fo, being 

 fcarcely more foluble in water than filex ; aod though its 

 habitudes with carbonic acid are partly fimiliar to thofe of 

 the alkalies, it does not acquire any tafte, or any degree of 

 caidlicity, by the lofs of this gafeous acid. Bar) tes and 

 llrontian, on the other hand, approach nearer to an alkaline 



nature than Time, in being very largely fohible in water, and 

 readily ciyllallizable from its folution m a determinate form. 

 They have therefore been adually enumerated as alkalies 

 by I'ourcroy, who reckons the following; potajh, foda, am- 

 monia, harytfs, :xnA Jlrontian. The two latter even ftand be- 

 fore the three ancient alkalies in their order of affinity with 

 moll acids, but, til! the intimate nature of the fixed alkalies 

 he fully cleared up, it will perhaps be proper to lellritt the 

 term alkali to the tliree above-mentioned, and to retain in 

 the clafs oi aHaline earths magncfia, lime, barytes, and llron- 

 tian, all of which, however tliey may be alk:dies in many 

 refpedts, differ liorn them in being unfuiible per fe in very 

 intenfe fire, and being entirely incapable of being volatilised 

 by the utmoil heat that has ever been applied to them. 



Alkali, in Botany. See Salicornia. 



ALKALINE, in a general fenfe, fomething that has the 

 properties of an Alkali. 



In this fenfe we fay, alkaline falts, alkaline fpirita, alka- 

 line fubllances, &c. 



Alkalini fah.s, confidered in their reference to the Materia 

 Medico, are known to poffefs antifcptic powers. Experi- 

 ments upon them, out of the body, fufficiently indicate and 

 attell thefe powers ; but Dr. Culleii obferves, that it is at 

 the fame time equally well known, that they are conftantly 

 imbued with fuch an acrimony, that they cannot by them- 

 felves be introduced into the body without acling more by 

 tluir llimulant than by their antifeptic powers. The volatile 

 alkali may fometimes be an ufcful remedy in putrid fevers ; 

 but it cannot, as fome have imagined, be given more freely 

 on account of its antifeptic powers, as it can never be gives 

 copioudy enough to have any effeCl by thete qualities. The 

 volatile alkaline falts (hew their llimulant power in everr 

 dofe, wherever the energy of the brain is weakened, and 

 confequently the atfion of the heart is languid, or requires 

 to be accelerated. In fuch cafes this ftimulus is among the 

 fafell, as it is always tranfitory ; and when their acrimony 

 can be covered, fo as to pafs the mouth and fauces without 

 irritation there, they may be given in larg." dofes from lo to 

 20 grains. Theft are prepared in two different ways ; one 

 of which is from fal ammoniac, which gives the ammonia of 

 the London Difpenfatory, or the fal ammoniacus volatilis, 

 and fpiritus falis ammoniac! of the Edinburgh. Thefe are the 

 purcil forms of the volatile alkali, the moil free from any ad- 

 hering animal fubllances ; but whilll the procefs of preparing 

 a volatile alkali from the bones or other folid parts of animals 

 continues, there will come into the (hops a fait and fpirit that 

 can hardly ever be fo pure, from fome empyreumatic animal 

 lubftance adiiering to it ; and fuch an adherence may probably 

 give fome peculiar quality to the fait and fpint, and render 

 it more antifpafmodic. It cannot be very confidcrable in any 

 dofes of the fait or fpirits given to adults, but it may pro- 

 duce more fenfible effedt in the fpafmodic affeftions of in- 

 fants. The liquid volatile alkali is commonly employed in 

 its mild ftate ; but by a diftillation of the fal ammoniac with 

 quick-lime, the alkali may be obtained in its cauftic ftate. 

 In this ftate it may be readily joined with fpirit of wine, and 

 gives the fpiritus falis ammomaci of the Edinburgh Difpen- 

 fatory, or the fpiritus lalis ammoniaci vinofus of that of 

 London. The combination affords an excellent menftruuin 

 for diffolving the feveral fetid fubftances employed as anti- 

 fpafmodics, and renders them more fuddenly dillulible, and 

 perhaps gives them a greater effeft in all fpafmodic affec- 

 tions. The cauftic volatile alkali is feldom adininiftered 

 alone ; but if its acrimony be covered while it paifes the 

 mouth and fauces, it may be vei-y fafely employed. Its 

 chief ufe is external, and when fmelled at the nufe, it gives 

 a more powerful ftimulus than the mild alkali can do. Its 

 acrimony is fo confidcrable, that when appUcd to the (kin, it 

 4T 2 readily 



