ACE 



often unequal in number to the petals. Germen fimple, 

 Handing on the before-mentioned di/k ; fyh one, or rarely 

 two; Jllgma one or two. Fruit oi feveral cells, or feveral 

 capfules, the cells or capfules three or two. Seeds in each 

 folitary, or at the utmoft three, attached to the inner angle, 

 fome of them frequently abortive. Corcuhm deltitute of 

 albumen, the radicle lying on the lobes. Stem arboreous, or 

 fljrubby. Leaves oppofile, wnhoxA Jiipulas. Flowers race- 

 liiofe or corymbofe ; fometimes by the abortion of one or 

 otner part becoming feparate in fex. 



Seft. I. Fruit of feveral cells, contains only Aefculus. 

 Seft. 2. Fruit of fe-veral capfules, oAj Jeer. 

 Sedt. 3. Confifts of genera allied on the one hand to the 

 Accra, on the other to Malpighi.5; ; fee that article. 

 Thefe are Hippocratea and TkryaUis. 



There is fome doubt, even in the mind of Juflieu himfelf, 

 whether Aefculus properly belongs to this natural order ; and 

 he juftly adverts to its great affinity to his Sapindi, (fee 

 that article,) with which its fruit undoubtedly very cloiely 

 accords. 



ACERAS, fo named from a, luithout, and y.i^a.q, a horn, 

 alluding to the want of a neftariferous fpur to the lip. — 

 Brown in Ait. Hort. Kew. v. 5. 191. Sm. Compend. Fl. 

 Brit. ed. 2. 128. — Clafs and order, Gynandria Diandria. 

 Nat. Ord. Orchidee. 



Gen. Ch. Cal. Perianth fuperior, of three ovate, con- 

 cave, equal, converging leaves. Cor. Petals two, linear- 

 lanceolate, concealed by the calyx, and about the fame 

 length. Neftary an oblong, flat, pendulous lip, much 

 longer than the petals, with two pair of deep, linear, flat, 

 dependent lobes, but no poflerior fpur. Stam. Filament 

 none ; anther ereft, oblong, attached by its back, parallel 

 to the fl;yle, of two ccUs, opening in front, the mafles of 

 poUen ciub-fhaped, each attaching itfelf, by a taper bafe, 

 to two glands in a fmgle pouch near the ftigma. Pifl. Ger- 

 men inferior, linear-oblong, twifted ; fl;yle columnar, very 

 fhort ; fl;igma below the anther, rather concave. Pertc. 

 Capfule oblong, with three blunt angles, twifted, of one 

 cell and three valves, fplitting by three lateral fiffures. Seeds 

 nu.Tierous, minute, each with a chaffy tunic. 



Eff. Ch. Calyx converging. Lip without a fpur, fiat. 

 Anther nearly terminal, fixed to the'ftyle, of two cells. 



This genus was firfl: eilabliflied by Mr. Brown, who 

 fcparates it from Ophrys, (fee that article,) on account of 

 the converging calyx, and efpecially the fituation of the two 

 glar.ds, which receive the polhn, being in one pouch, not in 

 two diilinft and diftant ones. 'I'he latter charafter, though 

 excellent in this inftance, appears to us in others lefs fatis- 

 faftory (fee Gymkadenia hereafter) ; and even in the cha- 

 rafters of Aceras and Ophrys, the flat lip of the former, 

 contrafled with the convex one of the latter, feems a more 

 obvious and natural dillinclion. In affinity the prefent 

 genus comes neareft to OiiCHls, but v;ants the fpur. 



I. A. anthropophorum. Green-man Aceras. Br. n. 1. 

 Sm. Compend. 130. (Ophrys snthropophora ; Linn. Sp. 

 PI. 1343. WiUd. Sp. PI. v,4. 63. Sm. FI. Brit. 937. 

 Engl. Bot. t. 29. Curt. Lond. fafc. 6. t. 66. O. n. 1264; 

 Hall. Hift. v. 2. 133. t. 23. O. anthropophora oreades ; 

 Column. Ecphr. 318. t. 320. f. I. O. flore nudi hominis 

 eifigiem reprifentans ; Rudb. Elyf. v. 2. 193. i. 6. Va^U. 

 Parif. t. 31. f. 19, 20.)— Lip of the neftary longer than 

 the germen — Native of dry calcareous paftures, in Italy, 

 France, Switzerland, and England, flowering in June. 

 The root confifts of two roundifli -ovate, nearly equal, 

 downy bulbs, or knobs. Herb fmooth, of a bright, 

 flightly glaucous, green, about ten or twelve inches high. 

 Leaves feveral, ovato-lanccolate, all radical, except one 

 •which /heaths the lower part of the ftalk. Spike eieA, of 

 10 



ACE 



numerous rather fcattered floiuers. Calyx convex, greee, 

 with reddifh-brown edges. Petals green, ereft. Lip pale 

 yellow, pendulous, near an inch long, in four narrow, 

 rather fpreading lobes, of which the two lowermoft are 

 ufually the fliorteft ; the whole flower having nearly the 

 ftiape of Orchis militaris, except the want of a fpur, and of 

 a fmall central lobe, often obfervable in that plant. We 

 have found at Valcimara, on the Apennines, what feenw a 

 mere variety with a red Up. 



2. A. anthropomorphum. Short -lipped Aceras. (Ophrys 

 anthropomorpha ; Willd. Sp. PI. v. 4. 63.) — Lip but half 

 the length of the germen. — Found on hiUs in Portugal, by 

 profeffor Linck. About a fpan high, the fpike an inch 

 long. BraSeas oblong, membranous, half the length of 

 the germen, nor does the lip exceed that proportion. Will- 

 denow thinks it can fcarcely be a variety of the former. We 

 have feen no fpecimen. 



ACERIC Acid, in Chemiftry, lately difcovered by pro- 

 feffor Scherer, of Vienna, in the fap of the acer campejlre, w 

 common maple. Its properties have been very imperfeflly 

 defcribed. The acerate of lime is white, flightly tranflucent, 

 has a weak acidulous tafte, and is not altered by expofure to 

 the atmofphere. 1000 parts of cold water diffolve 9 parts, 

 and 1000 paits of boiling water 17 parts of this fait. 

 Schweigger's Journal, iv. Thomfon's Chemiftry, iv. nev« 

 edition. 



ACETATES,or AcETiTES, a clafs of falte, the charaftcr- 

 iftics of which are, that they are all very foluble in water ; that 

 they are decompofed by the aftion of heat j and that they afford 

 acetic acid when diftilled with fulphuric acid. Accordingly 

 we have acetates of bary-tes, of potafh, of foda, of lime, of 

 ammonia, of magnefia, &c. See Acetic Acid. 



ACETIC Acid. It is now univerfally admitted by 

 chemifts, that the acetic acid differs in no refpeft from com- 

 mon vinegar, or what was formerly termed acetous acid, but 

 in the degree of concentration only. This opinion, firft 

 advancedbyAdet,has lately been fully confiiTned by the experi- 

 ments of Darracq and Proufl. What has been faid, there- 

 fore, on the fubjeft of acetous acid and vinegar in the Cyclo- 

 pedia, is to be underftood as applicable to dilute acetic acid ; 

 and the falts termed acetites are to be cor.fideved as acetates. 

 The following fafts are important, ar.d deferve a place here. 



The fpecific gravity of acetic acid does not enable us to 

 determine its ftrength. The fpecific gravity is ftated by 

 Dr. Thomfon to be a maximum when the liquid is a com- 

 pound of one atom, and three atoms water. Wlien the pro- 

 portion of water is either increafed or diminifhed, the fpecific 

 gravity diminifhes. Acid compofed of one atom real acid 

 and one atom water, and acid compofed of one atom real acid 

 and nine and a half of water, are flated by the fame chemifl 

 to h.-.ve the fame fpecific gravity. 



The following table, di-awn up chiefly from the experi- 

 ments of Mollerat by Dr. T., exhibits the fpecific gravity of 

 acetic acid of various ftrengths. 



