specific Gravity , and comparative Wear of Gold. i Sg 
this state, must then be removed by the solution of alum, 
called the blanching liquor. Now it is evident, that after this 
operation, the surfaces of the blanks or unstamped pieces, can 
no longer be regarded as standard gold. For, if copper alone 
forms the alloy, it must be dissolved and separated from the 
surface of each piece of coin ; and the same effect must also 
take place, with respect to the copper, in the alloy formed of 
copper and silver. So that, in the first case, each piece, when 
blanched, will consist of gold made standard by copper, covered 
with a thin coat of fine gold ; and, in the second case, each 
piece will be composed of gold made standard by silver and 
copper, coated with gold alloyed with of silver, or with half 
of the standard proportion of alloy, supposing the silver and 
copper to have been in equal quantities. As, therefore, the 
standard gold of which the pieces consist, is always, more or 
less, of a deeper colour than the coating or film of the finer gold 
which covers each piece, it must be evident, that when this 
coating has been rubbed and removed from the raised or pro- 
minent parts, these will appear of a very different and deeper 
colour than the flat part or ground of the coin. The reason 
therefore is sufficiently apparent, why gold which is alloyed 
with silver only, cannot be liable to this blemish. 
Upon a comparison of the different qualities of the three kinds 
of standard gold which have been lately mentioned, it appears, 
(strictly speaking,) that gold made standard by silver and 
copper is rather to be preferred for coin ; but, as gold made 
standard by copper alone is not very much inferior in its 
general properties, it may be questioned, whether the few ad- 
vantages which are thus gained, will compensate the additional 
expense of the silver required for half of the alloy ; and, indeed, 
