A G A
A G A
Elementary Ac at, confining of four colours; blue, fuppofed to exprefs water ; white, - the air ; red, the fire ; and brown, the earth. Velfch. Hecat. i. obf. 42..
Anthropomorphous Agate, thofe wherein the figures of men or women are exprcffed. Such is that mentioned by Kircher, reprefenting a :itroine armed ': That in the church of St. Mark at Venice, reprefenting a king's head adorned with a diadem. That other in the mufaeum of the prince of Gon- zaga, wherein the body of a man is feen; his head; heck; arms and legs, with all the cloaths, in a running pofture b . That mentioned by De Boot c , wherein a circle appears flruck in bruwn, as juftly as if done with a pair of com- pafles, and in the middle of the circle, the exact figure of a bifliop with a mitre on ; but inverting the ftone a little, an- other figure appears ; and if turned yet further, two other figures appear, one of a man, the other of a woman. That mentioned by Rumphius, on the plane whereof is diftinflly feen the figure of a pope at prayer, found in the ruins of an anticnt heathen temple near Rome ". But the moft cele- brated Agat of this kind is that of Pyrrhus, wherein were reprefented the nine mufes, each with their proper attributes, and Apollo in the middle playing on the harp : Achates in qua IX mufce & Apollo citharum tenens, non arte, fed natura fponte, ita dijcurrentlbus mastitis, ut mufis quoque fingulis fua redderentur infignia ". — [' Kirch. Mund. Subter. 1. 8. p. 30.
- Calceol. Muf. p. 21. ' De Gem. 1. 2. c. 95. " Thef.
Tab. E. Jour, des Scav. T. 50. p. 630. ' Plin. 1. 37. C. 3. See alfo Hardouin, Not. ad loci In the emperor's cabinet is an oriental Agat of furprizing bulk, being falhioned into a cup, whofe diameter is a Vienna ell, abating two inches. In the cavity, is found delineated, in black fpecks, b. xristor. s. xxx. Some account for the pbasnomenon from natural caufes, after Kircher's manner, who had feen a like ftone, in which were depided the four letters ufually infcribed on crucifixes, I. N. R. I. Some real crucifix he apprehends had been buried under ground, among Hones and other rubbiflb, where the infcription happening to be parted from the crofs, and to be received among a foft mould, or clay, fufceptible of the im- preffion of the letters, this came afterwards, by means of fome lapidific juice, or fume, to be petrified '. In the fame manner, that author fuppofes the Agat of Pyrrhus to have been formed. Others refolve much of the wonder into fancy, and fuppofe thofe ftones formed in no other manner than the
camieux, or Florentine ftones s [' Kirch. Mund. Subter.
T. 2. 1. 8. fed. j. p. 41. s J/ t lfch. i n Ephem. Germ, ubi fupra, p. 296.] SeeCAMAiEu, Cycl. To the clafs of anthropomorphous Agats, may alfo be re- ferred an Agat in the library of Francfort, reprefenting the heart, lungs, and part of the veins of a man. Koning. Regn. Miner, p. 106.
Lcucophthalmous Agats, thofe reprefenting the figures of eyes. Such is that mentioned by Velfchius ■', which he calls om- matia, or ompbopbthalmus : or thofe by Cardan b , and others, reprefenting the eyes of birds, fifties, wolves, called lycoph- thalmi ; of goats, xgophthalmi ; of oxen, boophthalmi.— [" 1 ecatoft. 1. obf. 22. b De Subtil, p. 290.]
Agats are alfo divided with regard to the affinities they bear to other ftones : hence the jafpachates, fardachates, &c. We find alfo onychates, between an onyx and an Agat, com- pofcd not of zones, or balls, but of plates perfpicuous and alh coloured. Crew, Muf. Reg. Soc. P. 3. p. 289.
Oriental fardonyx Agat, of an oval figure, and a white co- Jour, in the middle of which appears a body of water, which, upon fluking, is perceived to move \ This fpecies is other- wife called coccus, ovum foils, coccus paraquanorum; venter cryjlallmus, eetites gemmata b , &c. and may be referred to the antes kind '.—[' Settala, Muf. p. 80. h Johnjlon, Norn. Regn. Miner, tit. 2. c. 4. art. 2. p. 44. feq. = Baufch. de jEtit. p. 23.]
To this kind may alfo be referred the Agat of Chili, which has cryftals feen in it ; and another called berylloachates, con- taining pieces of beryls.
Ant achates, that which in burning yields a fmell of myrrh. This, though mentioned by Pliny among Agats, feems ra- ther to belong to the head of ambers, or bitumens. Others write it anchachates ; others, Jlaclachates. Salmaf. Exerc. ad aolin. p. 13?.
See farther concerning the hiftory of Agats, Nicolf. Lapid.
m • -P- » I R- , Gm "> Muf. p. 287. The figures of Agats, &"*£: Melloth p. 375. f cq . Their ftruflure, Woodward, Nat. Hift. Engl Foil. T. 2. p. 16. Experiments on them in the burmng-glafs, Giorn. de Letter, d'ltal. T. 8. p. 282.
the commerce and manufadure of Agats, Hought Coll
fl^'f^i 4 ,- 1 ' , The counterfe i"ng of Agats in glafs, Neri, Art ot Glafs, ]. 2. c. 37. p. 59.
Agats may be ftained artificially, by a folution of filver in KrZ taT^"* * erwards <*P°"ng t^ ftone, for fome hours,, to the fun. This operation fucceeds belt in whitdh
fo Ut iiV S f % be ( - obre '7 ed » ** no art has hitherto been able .to imitate the finenefs and beauty of the vegetable repre-
commonly called dendrites. And though art mould attain
to fuch a perfect imitation of nature in this cafe, as to deceive the eye, yet might the difference be otherwife difcovered. For if an Agat be coloured by art; it will lofe a great part of its colour, by heating it; and this colour may again be re- ftored, by adding the folution of filver in fpirit of nitre. Again, by putting a little aqiia-fortis, or fpirit of nitre, on Hie fufpecfed Jgat; without expofing it to the fun, the ar- tificial colours will difappear in a night's time ; and this co- lour may again be rcftored, by expofing the ftone to the fun for fome days. V. Du Fay, in Mem. Acad. Scienc. 1728. But Monf. de la Condamine has fince obferved, that even natural Agats, which, by the finenefs of the lines reprefented upon them, were beyond all fufpicion of art, yet fuft'ered a great change in their colours, by the application of aqua- fortis; , It is true; the change did not happen foon, as in Agats ftained by art, in which ten or twelve hours have been found fufficient to difcharge the colour. In natural Agats no change was obferved for three or four days ; but a den- drites put into aqua-fortis, having been forgot in a win- dow, and expofed to moift and rainy weather, was found very much changed, and the fainter parts of the vegetations were entirely effaced. V. Hift. Acad. Scienc. 1733. p. 35, 36. Edit. Amft.
So that the trial of Agats, by aqua-fortis,' feems precarious. However, fo far remains true, that the artificial colours foon difappear in fuch a trial ; whereas it requires fome di.ys to difcharge the natural colours.
Agat, among antiquaries, denotes a ftone of this kind, en- graven by art.
In which fenfe, Agats make a fpecies of antique gems ; in the workmanfhip whereof, we find eminent proofs of the great fkill and dexterity of the antlent fculptors. Several Agats of exquifite beauty are preferved in the cabinets of the curious. The facts, or hiftories, reprefented in antique Agats, with how much addrefs foever condu&ed, are become, at this diftance of time, many of them obfeure and dubious, and their explication difficult enough ; whence divers mif- takes have been committed, and numerous conject ures and difputes raifed.
The great Agat of the apotheofis of Auguftus, in the treafury of the holy chapel, antiently palfed for a triumph of Jofeph, when firft fent from Conftantinople to St. Lewis ; and 'tis probable, there are (till in many churches, even among thefe held and worfhipped for relicts, many of the remains of pa- ganifm, which the fimplicity of our anceftors has, as it were, confecrated ". An Agat, now in the French king's cabinet, had been kept feven hundred years, with great devotion, in the Benediflin abby of St. Evre at Toul, where it palled for a St. John the evangelift, carried away by an eagle, and crowned by an angel. Of late years, the heathenifm of it having been detected, the religious would no longer give it place among their relifls, but prefented it, in 1684, to 'he king: the antiquaries of the academy find it the apotheofis of Germa- nicus. Another Agat, in the fame cabinet, which had for- merly pafled for a triumph of Jofeph in Egypt, has been lately found to reprefent Germanicus and Agrippina, under the figures of Ceres and Triptolemus b . A curious Agat, in the cabinet of the French king, has been the fubjeot. of the inquiries of the academy of inferiptions c : it had been pre- ferved, for time immemorial, in one of the moft anticnt churches of France, where it had pafled for a reprefentation of paradife, and the fail of man ; there being leen on it two figures refembling Adam and Eve, with a tree, a ferpenr, and a Hebrew infcription around it, taken from the third chapter of Genefis, " The woman faw that the fruit was good, &c." The French academifts, inftead of our firft parents, find Jupiter and Minerva reprefented by the figures ; and as to the infcription, find it of modern date, being written in a Rabbinical character, very incorrect, and poorly engraven. But after this difcovery of the type, there ftill remained great difficulty in the explication of it. Some un- derftood it of the birth of Minerva, fpringing compleatly armed out of Jupiter's head ; others of the difpute of that goddefs with Neptune ; others, in fine, of the birth of Erich- thonus, and the fabulous traditions of the monfter half man half ferpent, begot by Vulcan and the Earth. But the pre- vailing opinion was, that the Agat reprefented fimply the worftu'p of Jupiter and Minerva at Athens— [» Vid. Hift. Acad. R. Infcrip. T. 1. p. 338. b Id. ibid. p. 340—544. • V. Hift. Acad. Infcrip.Tr. p. 337-339.]
Agats are fometimes denominated from the fubjefl reprefented on them.
Among the more curious, we meet with Tiberian Agat, Achates Tiberianus, a name given, by fome, to the famous Agat in the treafury of the French king's chapel, reprefent- ing the apotheofis of Auguftus, and the feries and portraits of the family of Tiberius and Julia, with divers foreign nations fubdued in war ; concerning which, many different explica- tions and conjectures have been advanced by the learned. V. Aft. Erud. Lipf. 1684. p. 255—259.
Ifiac Agat, Achates Ifiacus annularis, is a curious antique Agat at Rome, fo called, as reprefenting the head of Ifis, and being fet in a ring. Sig. Fontanini has given an expli- cation of this Agat, •
AGATHO-
