specific Gravity , and comparative Wear of Gold. 115' 
this had been effected, and the bar had been cast as already 
mentioned, then the bulk of the upper extremity was found to 
be 28,18, while that of the lower end was only 27,64. The dif- 
ference, therefore, between 27,27 and 28,18, shows, that an ex- 
pansion equal to ,91 had taken place in the upper end of the bar; 
and the difference between 27,27 and 27,64, also shews, that an 
expansion equal only to ,37 had taken place in the inferior ex- 
tremity ; and that thus a difference of ,54, in the expansion of 
the two extremities, had been produced merely by the pressure 
of the superincumbent metal. Had it not been for this circum- 
stance, there is reason to believe, that the general expansion of 
the whole mass would have been nearly the same as that of the 
standard gold mentioned in the Table, namely, ,66 ; for the ex- 
pansion of the upper end of the bar being ,91, and that of the 
lower end being ,37, the mean consequently must be ,64, which 
(taking into consideration the small difference in the quality of 
the two kinds of alloyed gold) may be regarded as a very near 
approximation to the statement in the Table. 
It will now be proper to notice other causes, which more or 
less influence the specific gravity of what is called standard 
gold. 
The most frequent cause of variations, in the specific gravity 
of gold made standard by silver or copper, is the unequal dif- 
fusion of the alloy throughout the mass of gold ; for an exact 
distribution of the alloy is not so easily made as may be ima- 
gined, especially when a large quantity of gold is to be alloyed. 
In Mints, this difficulty has however been considered, and 
an allowance has been made for it, which is called the Remedy 
for the Master of the Mint. 
According to this regulation, when the trial of the Pix, as it 
