120 Mr. Hatchett's Experiments on the various Alloys , 
specific gravity to that of gold. Therefore, as the upper end 
of each bar was uniformly of a much greater specific gravity 
than the opposite extremity, and as the metal was speedily con- 
gealed in the mould, and as the contents of each crucible, when 
poured, occupied the mould in an inverted order, (the metal at 
the bottom of the crucible being that which was last poured, 
and consequently being that which formed the upper extremity 
of the bar, ) there was much reason to believe that the alloy was 
not equally distributed, and that the melted mass, when in the 
crucible, varied in quality, so that the lower part consisted of 
gold above standard, and the upper part, of gold inferior to 
standard ; and, as but little alteration could take place when the 
metal was poured, this unequal quality remained, although 
inverted in respect to situation. 
In consequence of these experiments, it became necessary to 
contrast them with comparative assays. 
Several of these were therefore made ; but I shall only men- 
tion such as are immediately requisite to determine the question. 
It is proper, however, to remark, that the upper extremities 
of the bars which have been mentioned, were all found to be 
better than standard, while the inferior extremities proved to be 
worse. But the experiments to which I immediately allude are 
the following. 
Experiment i. 
Twenty-two ounces two pennyweights and four grains of 
gold, 23 car. grs. fine, were alloyed with one ounce seven- 
teen pennyweights and eighteen grains of copper. When the 
whole was completely melted, it was rapidly stirred, and was 
then suffered to continue in fusion during half an hour; after 
which, it was poured into a mould of iron. 
