specific Gravity, and comparative JVear of Gold. 191 
chiefly to fall upon only a few of the pieces. But it is not a little 
remarkable, that although these are often reduced nearly or 
quite to the state of plain pieces of metal or blanks, yet, upon 
being weighed, they are found to have sustained little or no 
loss ; and from this it appears, that the impressions have been 
obliterated, not by an actual abrasion of the metal, but by the 
depression of the prominent parts, which have been forced into 
the mass, and become reduced to a level with the ground of the 
coin. Pieces of hard gold would not so easily suffer by depres- 
sion ; but the real loss would probably be greater, they being, in 
the case of the friction of coin against coin of similar quality, 
more susceptible of abrasion. 
Upon the whole, there is every reason to believe, that our 
gold coin suffers but little by friction against itself ; and the 
chief cause of natural and fair wear probably arises from extra- 
neous and gritty particles, to the action of which the pieces may 
occasionally be exposed in the course of circulation. But still it 
must be repeated, that the united effects of every species of 
friction to which they may be subjected, fairly and unavoidably , 
during circulation, cannot produce any other wear than that 
which is extremely gradual and slow, and such as will by no 
means account for the great and rapid diminution which has 
been observed in the gold coin of this country. 
As the general results of each part of this inquiry have been 
noticed at the close of the different sections, a regular recapi- 
tulation would be superfluous. We may however observe, that 
the experiments on the various alloys of standard gold, concur 
with established practice and opinion to prove, that oniy two of 
the metals, viz. silver and copper, are proper to be employed in 
