EXPERIMENTS ON VARIOUS ALLOYS OF GOLD. 147 



3,50 grs. 4,60 grs. 13,S0grs. 7,60 grs. The fiandard filver Standard filver, 

 loll 3,70 grs. the fine copper 46,30. '""^ ^"^ <= 'PP«'* 



From comparing theeffeds produced wilh the number of re- rafed furfaces 

 volutions, it is obvious, that much more is loil in the fridlion ° '^ '"'^ • 

 of embofTed furfaces, than of plain. 



The experiments were afterwards varied by placing pieces Frlftion be- 

 of the different compofitions in fuch a manner, that in fome anrdUIlmUar 

 cafes the fri<5lion fhould be between fimilar pieces, in others, pieces. 

 between thofe differently alloyed. The refults of all ihofe 

 experiments are tabulated, but they would occupy too much 

 room to enter into them minutely ; and though, from un- 

 avoidable circumftances, fome little inaccuracies o€ca- 

 fionally occurred, they may be concluded, as Mr. H. obferves 

 to prove : 



1ft. That fine gold, or of 23 car. 3| grs. when expofed to I^ine go'*** 

 friction againfl; gold of an equal quality, under the preffure of 

 a confiderable weight, fuffers a very notable lofs ; and, al- 

 though various circumflances feemed to indicate, that but 

 little effed, in refped to abrafion, is produced under a lefs 

 weight, yet it mufl be remembered, that the firfl cafe may 

 occur.* 



Moreover, that fine geld, under all circumflances, is more 

 fubjed to have any raifed parts of its furface obliterated, than 

 any variety of alloyed gold ; not always, nor indeed fo much, 



* It is proper to remark, that the preceding experiments were Wear of coin 

 made under a much greater weight than can be luppofed to operate '" -^ ^f"vVc« 

 generally during the circulation of money ; and as, by fome pre- uiity. 

 vjous experiments, a lets weight was found to produce, during a 

 certain time, little or no efFeft, it may be fufpefted, that although, 

 under a greater prelTure, fine or very duilile gold luftains a greater 

 lofs than Ibme of thofe which are reduced to fiandard, yet, undef 

 a lefs preffure, or fuch as that which mofl commcnly prevails in the 

 courfe of the ufual wear of coin, the reverfe may probably be the 

 cafe ; for then the fame caufes operate with lets rapidity, during a 

 long period of time. From many various circumftances, there is 

 reaibn therefore to believe, that the wear of coin againft coin of a 

 fimilar quality is, under a fmall or very moderate weight, in the 

 inverfe ratio to the degree of duftilityj but this is only to be un- 

 derftood in the abovementioned cafe, of coin rubbed againfl coin of 

 equal quality. 



L 2 hy 



