14S EXPERIMENTS ON VARIOUS ALLOYS OF GOLD. 



by aflual abrafioii, as by having the protuberant parts preflTed 

 and rubbed into the raafs, in confequence of its extreme foft- 

 nefs and dudility.* 



2d. That fine gold, or of" 2.3 car. 3| grs. when rubbed 

 againft the various kinds of alloyed gold, always or generally 

 fufTers the greatefl comparative lofs. 

 Standard gold. 3d. That gold reduced to 22 carats, or to ftandard, by 

 filver, or by filver and copper, or merely by copper, fufFers 

 by fridion, under general and fimilar circuraftances, a fmaller 

 diminution than the fine gold abovementioned ; and, with or 

 without abrafion, the protuberant parts on the furfaces of 

 thefe pieces remain much more permanent, under all circum- 

 flances, than thofe of the fine gold. The difference of wear 

 between the three kinds of ftandard gold abovementioned, 

 does not in reality appear to be very confiderable ; but, upon 

 the whole, the preference may be given to gold alloyed with 

 a mixture of filver and copper, or to that which has only 

 copper for the alloy. 

 Gold with iron -llh. That gold made ftandard partly by the addition of 

 ••^ ''"• iron or tin, fuftains a greater lofs by friflion than either of the 



three kinds of ftandard gold above-mentioned. 



i8 carat gold, 5th. That gold reduced to 18 carats by copper, is more 



wuh copper, liable occafionally to wear, in a fmall degree, than the three 



kinds of ftandard golil which have been lately mentioned, 



provided that the friction takes place between pieces of equal 



quality ; but, in the contrary cafe, the principal lofs always 



falls on the foft or ftandard gold, when it is oppofed to gold 



of 18 carats, which isconfiderably harder. 



Gold much de- 6tli. That gold more debafed than that of 18 carats, fuch as 



baled with cop- ^^y alloyed with an equal proportion of copper, fufFers very 



confiderably nsore than any of the kinds hitherto mentioned, 



provided that the pieces are of the fame quality ; but, on the 



contrary, fine and ftandard gold experience a very great lofs, 



when expofed to the adion of this debafed gold, while the 



lofs of the latter is comparatively much lefs. 



pifadvantageof * This is, however, of much confequence ; for, although coin 

 foftnefs in coin, may not fufFer by aftual abrafion, yet, if the impreiRon made upoii 

 it can fo foon be deftroyed, it follows of courfe, that the pieces be- 

 come (although ftill allowed to be current) no better than mere 

 blinks, or fragments of a bar or ingot. 



7 th 



