A C I 



into acids by combination with oxygen, were fiippofcd by 

 Stahl and bis followers to be already acids united to phlo- 

 giston : thus fulphur, which accordinpf to the picfent the- 

 ory is a chemical element, and capable, by combination with 

 oxygen, of being converted into sulphuric acid, was, by 

 the Stahlians, confidcred as a compound of fulphuric atid 

 and phlo^iilon. 



The objed of the reformed ehemical nomenclature is 

 to denote, as much as poffible, the compofition of bodies 

 in the names appropriated to them ; thus fulphuric, carbo- 

 nic, and phofphoric acids exprefs the pcrfeft faturation of 

 their refpedive bafes, fulphur, carbon and phofphorus, with 

 oxygen. This rule, however, has by no means been uii- 

 formly adhered to, and the young ftudent in chemilliy, 

 reading of the benzoic, succinic or sebacic acids would 

 on tliis account be led into an error if he fuppof.d tliat 

 benzoe, amber, or fat were the acidifiable bafes of the acds 

 that bear their names. Almoft all fubllances are capable 

 of combining with oxygen, but it does not therefore follow 

 that they arc acidifiable bafes ; that the procefs of acidifi- 

 cation may take place a large proportion of oxygen feems 

 effentially necefTar/, otherwife the refult is only an oxyd. 

 Hence oxydable fubllances may be divided into thofe whicli 

 arc capable only of a low ftate of oxydation, or proper oxy- 

 dable bafes ; and into thofe capable of a further combination 

 with oxygen by which they acquire acid properties, or aci- 

 liifiabh bafes. Acidification may be performed in various 

 ■ways according to the temperature and the affinity of the 

 bafe for oxygen. The two great refei-voirs from which na- 

 ture procures her oxygen for the compofition of acids are 

 ■WATER ^nd at mofpheric air, the former confiding of oxy- 

 gen and hydrogen, and the other of oxygen and azot. The 

 chemill employs principally oxygen gas and atmofpheric air 

 at a high temperature, as in the formation of carbonic and 

 phofphoric acids by combuftion of charcoal and phofpho- 

 rus, or the nitric acid as in die formation of the sulphuric 

 and OXALIC aciJs. The acidifying procefTes of art are 

 generally more rapid than thofe of nature. 



ACIDITY, the quality which conftitutes or d-jnomi- 

 nates a body acid, or that fenfation of fharpnefs and four- 

 nefs which acids excite upon the organ of taile. 



ACIDON, a river of Peloponnefus, called alfo Jlcidas, 

 ■which united with Jardanus, near Anigrus. 



ACIDOTON, in Botany, a genus of the vionoeda poly- 

 endria clafs and order ; the characters of which are, that it 

 has male and female flowers on the fame, or a different tree ; 

 the calyx of the male is a five -leaved perianthium, and the 

 leaflets are ovate -lanceolate, and reflex; it has no corolla: 

 the flamina are numerous filaments from 35 to 40, placed 

 on a globular receptacle, the outer fhorter, the innei- longer 

 and upright : the anthers are cordate-o\'ate, wpright and 

 finall : the calyx of the female is a fix-leaved perianthium ; 

 the leaflets linear-lanceolate and Ipreading ; no corolla : the 

 piftiUum is a three-cornered germen ; the &.j\t fhort, acute, 

 thick and trifid at the tup ; the lligmas are toir.entofe and 

 reflex : the pericai^pium is a three-grained, hirfute, three- 

 celled capfule ; and the feeds arc folitary and ovale. Tliere 

 is one fpecies, i)/s. A. ureas, ?. native of Jamaica, defcribed 

 Lv Sloane, though he never iavt' the flower and fruit, which 

 grows to the height of eight or nine feet. Miller's Did. by 

 Martyn. This, in Gmelin's edition of LimicEus, is a genus 

 of the poJyandria monogyriia clafs and order. 



ACIDOTON is alfo a fpecies of Adelia. 



ACIDULA, in jiticient Geography, a fountain of Italy, 

 Ticar Linternum, to the waters of which, probably impreg- 

 nated with fixed air, or carbonic acid, Pliny afcribes a falu- 

 tary effcd, as an antidote to ftone and gravel. 



A C I 



ACIDULjE, Eaux acidtdes, Fr. a fpecies of m'merat 

 waters, dillinguifhed by their fparkling appearance w'cn 

 poured from one velfel into another, and by their brifl< ci- 

 dulous talle ; they contain a confidcrable quantity of free 

 carbonic acid to which thefc prip^rties are owing. 



ACIDULATED, a term denoting a ly thing blended 

 with acid juic^.s ii order to givj it a coohi'ls and briilinefs. 



ACIDULOUS denotes a thing that is ll.ghtly acid : it is 

 fynonymous with the vrordful-acid. 



ACIDULUM, Aci.iuL; Fr. a term ufed in the new 

 che-.nic:il nomenclature, to exprefs a genus of native com- 

 pound falts, in which the alkaline bafe r. fupcrfat-.irated with 

 acid, and which tlicrefore are employed in various chemical 

 procefTes, and for economical purpoles as acids. We are at 

 prefent acquainted with two jpccies, the tratareous acldiN 

 lum, or aridulins tartrite of po.'a/L, and iKj oxalic acidu- 

 lum, or acidulous oxalat oi polajh. 



ACIDUM ¥mG\JE,—CauJlicum—Jeidcgras. Fr. Fett^ 

 fuvre GeiTii. 



In the year 1 764, when the abilities of Macquer, Bergman, 

 Black, and Scheele, had already dlfcovered many important 

 chemical fads, which were kvith difficulty explicable on the 

 Stahlian theory, and when the rigorous method of demonftni- 

 tion fo honourable to the prefent age had not as yet been uni- 

 verfally atfented to, there appeared in German a volume of 

 EiTays on the fubjed of Lime, by Fred. Meyer an apothe.» 

 caiy of Oinaburg, announcing the difcovery of a new 

 chemical agent, the acidum pingue, with an extenfive theory 

 dependent upon it, and, in many refpeds, effentially con- 

 trary to the conclufions of Dr. Black, from his admirable 

 experiments on the fame fubjed. Several of Meyer's 

 countrymen becaine the zealous advocates of his fyflem, 

 and it was foon taught publicly in many of the German 

 fchools. At length, in 1769, Jacquin publifhed an able 

 vindication of Black, intitled Exanun chemicum doctririjs 

 Meyerian/s de acido piiigui, et B'achiarns de acre Jixo refpedn . 

 calcis. Vindohonx. This work brought out in the courfe 

 of the following year a reply by Crantz, and another by 

 Fourchy, both of them ftrenuoufly defending the dodrineof 

 Meyer. It does not appear that any thing more was ex- 

 prefsly wTitten on either fide, but by the accumulation of 

 the fplendid difcoveries of Lavolfier, PrielUey, &c. the 

 theory of Meyer was fllently ovenvhelmed, and the con- 

 clufions of Black unequivocally eftabliihed. Nearly the 

 fame hypothefis was afterwards revived by Sage in the ef- 

 feds attributed by him to an imaginary principle, the igneous 

 acid, (acide igne) but wliich has not been fince rccognifed 

 by any chemical writer. 



The fads upon which Meyer's dodrnie is founded are the 

 following. Mild calcareous eartli being kept at afulli-ed heat 

 for a certain length of time is converted into quicklime ; this 

 change, whic'i at prefent is accounted for by the volatiliza- 

 tion of its water and carbonic acid, was by Meyer fup- 

 pofed to be owing to the combination of the acidum pingue 

 with the calcareous bafe, and the confequcnt difengagement 

 of its wnter ; hence originated a cauflic earthy fait foluble 

 in water ; if to this lime water, a mild alkali, be a.dded, a 

 decompofition takes place, the acidum pingue unites by 

 pieference with the alkali, making it cauflic, while the cal- 

 careous earth combines with a portion of water, becomes 

 infoluble, and is precipitated in the ftate of mild calx. So 

 for the theor)' of Meyer was fupported by fads which, 

 however equivocal and imperfed, had at leafl forae plaufi . 

 bility. But, in his attempt to raife thi? caujlitum to the 

 rank of hn acid, and of a prime agent In chemical pheno- 

 mena, he deviates into the wildefl conjedures without the 

 fnadow of a fad in their fuppoit. I'he following are the 



chief 



