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always furrounded by a blaft of air, which is fcnt forth from 

 them in all diredlioiis; hence, if the electric matter find a 

 more ready paffage through one part of the earth than 

 another, a wind will be found to blow from that quarter. 

 If, therefore, one of thcfe places happens to be in the At- 

 lantic ocean, near the coall of France, or in the bay of 

 Eifcay, the cleclric matter which has been received at the 

 equator during an aurora borealis, will be difcharged there 

 fome time after, and confequently a wind will blow from 

 that quarter, which will be from the fouth-weft to thofe 

 (hips which are in the Englifli channel. It cannot be ima- 

 gined, however, that all the matter can be difcharged from 

 one place; and tl^erefore, according to the different fitua- 

 tions of thofe eleftrical vents, winds may blow in different 

 direclions; and thus the fame aurora borealis may produce 

 a fouth-weft; wind in the Englifli channel, and a north-wtft 

 one in Scotland." 



AuROR.'i Surgeiu, a phrafe ufed by Alchem'tjls, to exprefs 

 the multiplicative virtue of the philofopher's Hone. 



AUROREA, in Onihhology, a fpecies of Motacill.ii, 

 called by Latham the Daurian -warbler. This bird is 

 fulvous beneath; crown and upper part of the neck hoary; 

 front whitilh; throat "black ; back and wings black, with 

 a white triangular fpot on the latter; tail-feathers fulvous, 

 two middle feathers black. Pallas. This bird is the fize of 

 the red-ftart, and inhabits Siberia to the confines of China; 

 moll common in the vicinity of the river SeUnga, among 

 willows. 



AUROS, in Geography, a town of France, in the depart- 

 ment of the Gironde, and chief place of a canton in the 

 diilricl of Bazas, five miles north-eail of Bazas. 



AUROTA, in Enlomology, a fpecies of Papilio {Dan. 

 Cand.) that inhabits the coaft of Coromandel. The wings 

 are entire and white; margin black, fpotted with white; 

 pofterior ones yellow beneath. Cramer. 



AUROTUS, a fpecies of Phal/t:na, of the larger kind 

 of Bombyces, with falcated wings; above and beneath of 

 the fame yellowifli colour ; with a white band, and tranf- 

 parent lunar fpot in the dilk of each. This kind inhabits 

 America, and was dcfcribed by Fabricius from a fpecimen 

 in the Mufeum of the late Dr. Hunter. 



AUROUX, in Geography, a town of France, in the de- 

 partment of the Loierre, and chief place of a canton m the 

 ditlricit of Langogne, feventecn miles north of Mep.de. 



AURULENTA, in Entomology, a fpecies of Bupres- 

 Tis, of a fomewhat oblong or rather narrow form, that in- 

 habits Carolina. The wing-cafes are faftigiate, bidentated 

 at the end, and green with a golden margin; body golden; 

 thorax (lightly dotted. Fabricius. 



AuRULESTA, a fpecies of Cicada {Ranatra Sec), of 

 the fize and (hape of cimcx obtufa. The head and thorax 

 are rufous; wing-cafes brown, cinereous at the tip. A nativs 

 of Cayenne. Fabricius. 



Aurulenta, a fpecies of Sp HEX, the head and thorax of 

 which are covered with golden coloured down ; the abdomen 

 black, with the margin of the fegmcnts a(h-colour, and the 

 legs rufou". This infeft is of the middle fize, and inhabits 

 China. Fabricius. — Obf. Both Fabricius and Gmtlin have 

 evidently defcribcd this infeft twice, once under the Ipecilic 

 name aurulenta, and afterwards under that of aurata ; or at 

 leaft the only difference in the defcription is, that the legs 

 are not mentioned in the fpecific character of the latter, but 

 we are told in the general defcription, that they are of a ferru- 

 ginous colour, which approaches pretty nearly to tkat of 

 rufous; and as both kinds are laid to be natives of Aha, the 

 one of China, and the other of India, we have no doubt tliat 

 Fabricius has inadvertently defcribcd the fame infed in both 



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inftances; and that Gmthn, without inquiry, has implicitly 

 relied on his authority. See Aurulenta, Fabr. Mant. 

 Inf. I. p. 274. n. 10. and Fabr. Mant. Inf. i. p. 276. n.45. 



AUliUM, in Natural H'ljhry, denotes gold. See Gold. 

 The word is chiefly ufed amorig us as applied to certain 

 chemical preparations, whereof gold is the bafis, or prin- 

 cipal ingredient — Such are the aurum petabile, aurum fuU 

 m'mans, &c. 



Aurum Fulm'tnans, in Chem'ijlry. See Gold, Salts ef. 



Aurum Mofaicum, mujicum, or mufivum. See Tin. 



Aurum Petabile, potable gold, a liquid preparation of thif 

 metal formerly much ufed in medicine, but now entirely ob- 

 folete. 



The difcovery of an univerfal medicine was a faTourite 

 fpcculation of the ancient alchemifts, and they eagerly in- 

 dulged the hope of finding it in the precious metal which 

 alone was the object of all 'their attention. Hence we meet 

 with a number of vaunted preparations of gold, moll of them 

 kept fecret, but fome revealed by the inventors, all of which 

 had a certain reputation for a time, but are now funk int» 

 deferved neglcdl. 



Two methods were praftifed for the preparation of this 

 metal as a medicine ; the one was to grind gold leaves to a 

 moil impalpable powder, by a trituration of fcvcral days or 

 even weeks; the other was to difTolve the raetal in its proper 

 menftruum, the nitro-muriatic acid, and to mix it with ether 

 or any effential oil, which by operating a reduction of the 

 metal in a very divided (late, has the power of feparating it 

 from its acid folvcnt. As this faCl is important in the che- 

 mical hillory of this metal, we (hall mention it more parti- 

 cidarly under the article Gold. 



The potable gold of Helvetius, retained till within thefe 

 few years in tiie Paris pharmacopceia, is thus prepated. 

 " Dilfolve half a dram of pure gold in two ounces of aqua 

 regia, employing a gentle heat; to the folution add one 

 ounce of oil of rofemary, (liake the mixture, and immediately 

 the gold will quit the acid, and unite with the effential oil, 

 giving it a beautiful yellow colour; this is to be decanted 

 from off the acid which remains at the bottom, and mixed 

 with fifteen ounces of reclified ipirit of wine, which forms 

 the potable gold." 



The dofe is from C\^ to twenty drops. 



The powers of this medicine are fuppofed to be in a high 

 degree cordial, (limulating, and tonic. 



In fuch a preparation as this, when the quantity of gold 

 in each dofe is fo extremely minute (though ilill fufficient to 

 give it fomfewhat of a yellow colour), it requires little difcem- 

 ment to fee that all the medicinal powers, wiiatcver they 

 may be, depend altogether on the ethereal oil and the 

 ardent fpirit with which the gold is united; and accord- 

 ingly it is now entirely rcjefted in every pharmacopceia. 



A fairer trial, however, has been made of the virtues of 

 gold in medicine. We read that fome of the crafty alche- 

 mical empirics had the addrefs to perfuade feveral of their 

 noble patrons that the royal metal was peculiarly well 

 calculated to cure the difcafes of perfons ot exalted rank; 

 and under this circumltance this precious metal has been 

 fwallovved in larger doles. Thelc, however, are not the 

 follies of the prefeiit day, pubhc crcduUty being diverted 

 into other channtls. 



From all that we know concerning the properties of gold, 

 it appears, that its inertnefs when taken into the human 

 body, depends on th.c eaie with which it is reduced to the 

 reguline Hate, and when in this (late, its abfolute infolubi- 

 lity in anv of t!»e animal juices. As the nitro-muriate of 

 gold polfeffes the power, in a very high degree, of tlaining 

 alraoft every animal matter, it is probable that it would act 



