H4 Mr. Hatchett’s Experiments on the various Alloys, 
iron, by which a bar was formed, nearly 12 inches in length, 
one inch in breadth, and one quarter of an inch in thickness. 
Every possible precaution had been taken, to mix and diffuse 
the copper uniformly throughout the gold; and the assays which 
were made subsequent to the casting, fully proved that the 
mixture was perfect. When, however, the specific gravity of the 
two extremities, or of the top and bottom ends of the bar, was 
examined, it appeared, that the specific gravity of the upper 
end was 17,035, while that of the lower end was 17,364. So 
that, although the quality of the bar was perfectly equal in every 
part, yet, by the pressure of the superincumbent metal, the lower 
extremity, or that which was formed in the bottom of the mould, 
had acquired a very superior degree of density. 
Now, from the foregoing Table it appears, that the bulk of 
442 grains of gold, 23 car. g\ grs. fine, is very nearly 23,05, 
and that the bulk of the fine Swedish copper employed in these 
experiments is, for 38 grains, equal to 4,27; consequently, the 
total bulk of these two metals, before combination, amounts to 
27,32. Moreover, when these metals were combined, then 
the bulk of 480 grains of this standard gold was 27,98; so 
that an expansion equal to ,66 had taken place, in conse- 
quence of .the combination of 442 grains of the gold with 38 
of the copper. In order to compare this result with the bar 
abovementioned, it must be first remembered, that the quality 
of the latter was, throughout, 8 grains better than standard ; 
and, consequently, 480 grains of this gold, consisted of 442 ,66 
grs. of fine gold, and 37,34 grs. of copper. The bulk, therefore, 
of the 442,66 grs. of gold amounts to 23,08, while that of the 
37,34 grs. of copper is 4,19; which, added together, gives 27,27 
for the total bulk of 480 grains before combination. But, when 
