A E T 



no reference to this, or to any other particular plant what- 

 ever. 



AEROSTATION, col. 5, 1. 39. for ^4 '•• «40 ; 

 col. 27, I. 17, for circumference r. diameter. 



iERUGINOSUS, in Ornithology. See Moor Buz- 

 ZAHD. 



^SCHYLUS, col. 2, 1. 24, for wrote r. chofe ; 1. 29, 

 for furious r. ferocious ; 1. 36, for referred r. tranf- 

 ferred. 



^SOP, col. 2, 1. 60, r. lived more than 350 years, &c. 



^sop, Clodius, 1. 2, after Rome, add, B.C. 79. 



AESTIVATIO, in Botany and Vegetable Phyjwlogy, a 

 term ufed by Linnseus for the mode in which the petals, or 

 the fegments, of a corolla are an-anged with refpeft to each 

 other, particularly before they expand. (See Corolla.) 

 The word comes from ajlas, fummer, and tejil-va, fumnier- 

 quarters, fummer being the ufual flowering fcafon, and the very important cl 

 corolla the (helter or accompaniment of the organs of chemifts, refpeft: 



fecundation. So Vernatio exprefles the arrangement of the 



leaves of plants in the bud, or, in other words, their vernal 



condition. Aejlivatto imbrkata, expreffes the divifions of 



the corolla being imbricated, or folded over each other, 



either from left to right, that is, with the motion of the 



fun, as in Cijlus ; or the reverfe, of which latter Linnasus 



.- has in his manufcripts mentioned Phlox as one example, and 



. -we would point out Hypericum as another. Aejlivatio val- 



■vata is when the divifions of the corolla meet in the bud 



like valves, fide by fide, as in Protca and its allies. Of this 



^Periploca is an inftance, notwithftanding the obliquity 



. obfervable in the fegments of that flower after expanfion. 



Linnaeus, in the MSS. above cited, fpeaks of Po-onM as 



having, like its near relation Aconitum, one petal exterior 



to all the reft, though the corolla is what would be termed 



regular in the firfl: genus, and very irregular in the fecond. 



Such a diverfity indeed is of fmall moment, for Mr. Cor- 



rea has obferved that every natural order, as far as he 



could examine, pofleffes irregular and regular flowers. In 



general the direftion of the parts of a corolla, as to their 



. aeftivation (if we may ufe that word), are invariably alike 



in genera of the fame natural order. But Hermannia, 



(fee that article,) affords a remarkable exception, every one 



of its fpecies that we have feen bearing two jloiuers on the 



A F F 



(Thlafpi faxatile ; Linn. Sp. PI. 901. " Schkuhr Handb. 

 v. 2. 223. t. 180." See Thlasi'I, n. 6.) — Longer fila- 

 ments diftinft. Leaves oblong, tapering at the bafe. — 

 Native of the fouth of Europe. Cultivated by Miller in 



1759- 



2. Ae. monojpermum. One-feeded Aethionema. Ait. 

 n. 2. — " Pouch fingle-feeded, without valves. Leaves 

 oval or obovate." — Native of Spain. Cultivated in 1778, 

 by Lee and Kennedy, at Hammerfmith. A hardy biennial, 

 flowering in July and Auguft. We have feen no fpecimen 

 of this fpecies. Our doubts refpefting the genus may be 

 found under Thlaspi. 



AFER, DoMiTius, col. 2, 1. 11, for vanity r. variety. 



AFFINITY, in Chem'ifiry. The celebrated dodlrine of 



Bergman is the laft in order difcufled under the article 



Affinity in the Cyclopiedia : fince that time, however, 



hanges in opinion have taken place, among 



ing the nature and caufe of chemical affi- 



nity. Some of thefe are mentioned in fubfequent parts of 

 the Cyclopasdia, efpecially in the articles Chemical Propor- 

 tions, Simple Bodies, and Atcmic Theory ; but it may 

 not be deemed fuperfluous to give a fummary and con- 

 nefted view of the whole in this place. 



Bergman's doftrine of eleBive affinity, fo amply explained 

 in the article above referred to, was univerfally admitted 

 among chemifts till 1803, when BerthoUet pubhfhed his 

 Differtation on Affinity in the Memoirs of the Inftitute, and 

 about the fame time his Chemical Statics. BerthoUet confi- 

 dered affinity as an attraSion exiiling between combining 

 bodies. This attraftion he appeared to confider as fimilar 

 in its nature to that which exifts between the planets, or in 

 fliort, the principle of gravitation. It confequently, in his 

 opinion, increafed with the mafs of bodies. According to 

 this doftrine, therefore, bodies which have an affinity or 

 attraftion for one another, have a tendency always to com- 

 bine, in a greater or lefs degree, chiefly in proportion to 

 their mafs. Thus, though barytes appears to poffefs a 

 ftronger affinity for fulphuric acid than potafh, yet if we 

 prefent a great quantity of potafh to a fmall quantity of 

 fulphate of barytes, the potafti will feparate a portion of 

 the acid. 



According to BerthoUet, therefore, affinity is not elec- 



fame ftalk, has the petals of one of thofe flowers rolled to tive. A fubftance which has a ftronger affinity is not capable 



of feparating entirely thofe which have a weaker, unlefs 

 fome other caufe than mere ftrength of affinity operates. 

 Inftead of feparating entirely the weaker body, it divides 

 with it the bafe to which that body was united, each com- 

 bining with a part of fuch bafe in the compound proportion 

 of the ftrength of its affinity and of its quantity. 



But no fafts in chemiftry are better eftabliflied than 

 thofe in which the addition of a third body frequently fepa- 

 rates two fubftancesprevioufly united, the third body taking 

 the place of one of the conftituents, which is thereby fepa- 

 rated altogether. Thus, if fulphuric acid be dropped into a 

 folution of nitrate of barjtes, or potafti into a foliition of 

 nitrate of lime, the fulphate of barytes and the lime will 

 precipitate, leaving, in the firft inftance, the nitric acid in a 

 free ftate, and in the fecond, the potafti combined witti the 

 nitric acid inftead of the hmc. Thefe and many other 

 well-known fafts appearing, at firft fight, contrary to Bcr- 

 thoUet's doftrine, it was neceflary for him to reconcile tlicm 

 to it. For this purpofe, he called in the aid of the difi^erent 

 modes of exiftence of bodies. According to him, therefore, 

 whenever decompofition takes place, it is owing either to the 

 infolubility or the elajlicity of the ingredient which feparatef. 

 Sulphate of barytes being infoluble in water, while nitrate 

 of barytes aod nitric acid arc foluble in that liquid, it muft 



happen, 



the right, while thofe of the other are difpofed in a con- 

 trary pofition. Mr. Brown, in his learned Prodromus of 

 New HoUand plants, has paid more attention to tlie seftiva- 

 tion, in defining his natural orders, than any other botanift, 

 and the term tjlivatio vahata is, if we miftake not, his own 

 invention. 



iETH, 1. 4, infert after Bruftels. It is the chief place 

 of a canton, in the department of Jemappe, and diftridl of 

 Toumay. The place contains 7634, and the canton 14,828 

 inhabitants. The territory includes 1 1 5 kiUometres, and 

 1 1 communes. See Ath. 



AETHIONEMA, in Botany, fo named by Mr. Brown, 

 apparently in aUuilon to fome tawny or fun -burnt tinge in 

 the ftamens, from aiOi-, to fcorch, and n\i.y., a Jlamen. We 

 perceive in our dried fpecimens an occafional purple hue in 

 thefe parts. It may perhaps be more remarkable in the 

 fpecies we have not feen. — Brown in Ait. Hort. Kew. v. 4. 

 80. — Clafs and order, Tetradynamia Siliculnfa. Nat. Ord. 

 ' Siliquo/is, Linn. Crucifer^, JaW. 



Eft. Ch. Pouch with boat -like winged valves ( fometimes 

 not burfting). Longer filaments either combined, or finely 

 toothed towards the top. Infertion of the calyx unequal. 

 Brown. 



I. Ae. fasalile. Rock Aethionema. Ait. n. 1. 

 J2 



