t§o On the dueftiony ivhether mixed Metals 



flriick exhale a certain odour. The antients were acquainted 

 with the finell of the femi-metals, experiments on which 

 were made by Boyle. But I do not find in any of the mine- 

 ralogical works of the moderns that the purity or alloy of the 

 Hoble metals, fuch as gold and filver, can be afcertained 

 merely from the external charatler of fmell. Among the 

 antients, however, fmcll was a principal charaiSlcr of metals. 

 The fined compofitions were diftingiiifiied merely by their 

 odour. Arrian on Epiftetus * fays exprefsly thaft an expert 

 money-changer (banker) nuift necelfarily have the fenfe of 

 fnielling in an exquifite degree. " Behold," fays Epi«^^etus, 

 *' in money affairs, when our intered is concerned, the art 

 which has been invented, and the means which the changer 

 employs to try the money. He tries them by the fight, by 

 the touch, by the fmell, and even by the hearing f ; for he 



throws 



* I. 20. p. iio. edit, of Schwcighaufer. 



+ And why not uy die tafte ? to go through the whole circle of the 

 organs of ilnie. Tliis method was alfo known to the ainicnts. The 

 ule of the touch^ton'., In/ih Lvilitis (fee Theocritus, xii. %h\ and Flinv, 

 jtxxiii. S. with ohlLrvnticns by M. Schneider, AnalcBa ad Hiforiari R:i 

 MetaUlcte, p. ^.liwa's, however, the moft common method of trying gold, 

 which when it hid undergone this teft was called obryzum. Pliny fpraks 

 alfo, in the place above quoted, of trials by fufion. There is a curious 

 paffage in Herodotus, vii. lo. rcfpe£ting the true meaning of which 

 mineralogifts, in my opinion, have not yet agreed. Artabanus faid to 

 Xerxes before the Pcrfians affembled, that pure gold could be diftinguiflied 

 bv rubbing it againft other gold. VVeficiing, p. j ii. 30. confidcrs this 

 idea fo abiurd, that inftead of /» rf/Z' (9r2(iaTpi4.'«'Mfi') he prefers reading t6 

 compare (a-v/xfrnreu). Larcher, in his translation of Herodotus, vol. v. 

 p. 272, adopts, in part, the opinion of Weffeling on this paffage : he fays 

 the word in the Greek text is 7rariaTpi4»v^-«v. But it is not by rubbing gold 

 againft gold that we can diftinguilh which is the beft ; 1 do not therefore 

 hefitate to adopt the reading of Sancroft's manufcript, smxv h Infm a-vyxfi- 

 »iiTat, which indicates the only manner of afcerraining pure gold before the 

 ufe of the touchflone v\3s known. I confefs, however, that '!rapoTfl^^.«^E? 

 has always appeared to me preferable, becaufe c-jyK;v/i\T m has the appear- 

 ance of an interpolation, ^nd may have been fublbtutcd by fome one who 

 did not uiiderfia:id the other word. My opinion is confirmed by C. Girod- 

 Chantram, who, when confultcd on this paffage, declared that it might be 

 retained without any change, becaufe, pure gold being fofter than that al- 

 loyed witli copper, the leaft pure metal muft make an impreflion on the 

 ©iher, and thus atford the means of afcertaining it. The proof of this 

 affcrtion was eftablilhed at the time when it was propofed to the National 

 Convention to coin new money in France without any alloy. The advan- 

 tages of tliis method were found to be couiuerbaLniccd by fome inconve- 

 niences, one of which was, that friftion is more deftrudtivc to pieces of 

 ptire metal than to thofe the haidnefs of which is increafed by alloy — Rap- 

 prt par Lo.fd, Sept. 15, 1793. The National Convention charged the 

 Academy of Sciences to make experiments, which fuliv confirmed the 

 eifcft in regard to continual friftion on pure and alloyed metals. " It 

 thence refulted," fa/ the commiilloiicrs in their report, " that the lofs cx- 



|)erien(;ed 



