specific Gravity , and comparative Wear of Gold. 119 
distribution of the alloy, two pieces were taken from the opposite 
extremities of each bar, and were examined as follows. 
1. 
2. 
3 - 
4 - 
5 - 
6 . 
7 - 
Gold made standard by silver 
Gold made standard by equal parts of 
silver and copper - 
Gold made standard by copper 
Gold made standard by lead 
Gold made standard by equal parts of 
copper and iron - 
Gold made standard by an alloy com- 
posed of \ copper and ^ of tin 
Gold made standard by antimony 
Specific 
gravity. 
Upper end. 
Lower end. 
18,273 
17,186 
18,062 
16,659 
18,492 
16,680 
18,124 
18,037 
17,068 
16,924 
1 7’55 1 
i 6>747 
17,121 
16,707 
Each of the bars weighed two pounds Troy ; they were one 
inch broad, and £ of an inch in thickness ; and were cast in a 
mould of iron. 
From these experiments it appeared, that the upper extremities 
of these bars, or those which had been formed at or near the 
mouth of the mould, were uniformly of greater specific gravity 
than the opposite ends of the same bars, or those which had 
been formed in the bottom of the mould ; and that the smallest 
variation in the specific gravity of the two ends of a bar, was in 
that which consisted of gold alloyed with lead. 
The above mixtures were made with the usual precautions, 
such as rapid stirring, and pouring ; but, nevertheless, it seemed 
that the alloy had never been completely and uniformly distri- 
buted throughout the mass of gold ; or, if it really had been 
well diffused and mixed, that it subsequently (although in a 
very short time) had again separated, according to its relative 
