154* 



Its difadvan- 

 tages; 



with equal parts 

 of filver and 

 copper ; its ad- 

 vantages ; 



jts difadvan- 

 tages : 



alloyed with 

 copper alone. 



EXfERIMENTS ON VARIOUS ALtOYS OF GOLD. 



Ift. The additional expence attending the ufe of lilver as 

 an alloy. 



2d. The extreme pale yellow colour. And, 



3d. That, from its great du6lility, it is almoft as liable to 

 have the impreffions which have been made upon it obliterated, 

 as thofe which have been made upon fine gold. 



411 things being therefore confidered, gold alloyed only" 

 with filver, does not appear to be fo proper for coin as may 

 at firft be imagined. 



Gold made standard by a mixture of equal parts of filver 

 and copper, is not fo foft as gold alloyed only with filver ; 

 neither is it fo pale, for it appears to be lefs ren^oved from the 

 colour of fine gold than either the former or the following 

 metal. 



Gold alloyed with filver and copper, vvhen annealed, does 

 not become black, but brown ; and this colour is more eafily 

 removed by the blanching liquor, or folution of alum, than 

 when the whole of the alloy confifts of copper. It may alfo 

 be rolled and flamped with great facility ; and, under many 

 circumftances, it appears to fufTer lefs by friflion, than gold 

 alloyed by filver, or by copper alone. 



But, after it has been fubjedled to the ordinary friflion 

 which muft take place during the circulation of money, it is 

 liable to appear of a deeper colour in thofe parts which are 

 prominent, and are confequently the mofi cxpofed to fri6tion. 

 This defefi arifes from a caufe which will foon be explained, 

 but it cannot be regarded as an objedlon of any weight. 



The laft kind of flandard gold which remains to be men- 

 tioned, is that which is alloyed only by copper. This is of a 

 much deeper colour than thofe which have been hitherto no- 

 ticed, and it is flighlly harder than either of them ; but ne- 

 verthelefs it is very du6tile, provided that the copper be pure. 

 It requires to be annealed, and then becomes nearly or quite 

 black : which colour is not fo eafily removed by the blanch- 

 ing liquor, as that- which is produced by the procefs of 

 annealing, upon gold alloyed with a mixture of filver and 

 copper. 



It fuffers lefs by many of the varieties of fri6lion, than gold 

 which is alloyed with filver ; but, in fome cafes, it feems to 

 wear rather more than gold alloyed with filver and copper ; 

 the difference is not however very confiderable. 



This 



