specific Gravity , and comparative Wear of Gold. 55 
Experiment iv. 
Eighteen pennyweights and ten grains of the fine gold, were 
alloyed with one pennyweight and ten grains of copper, and, 
when in perfect fusion, four grains of antimony were added. 
The external colour of the ingot was like that of Experiments 
11 . and hi. It was very brittle, and the grain of the fracture was 
similar to Exper. 111. excepting that it shewed a small degree of 
metallic lustre. 
Experiment v. 
To one ounce sixteen pennyweights and twenty grains of the 
fine gold, alloyed with three pennyweights and three grains of 
copper, one grain of antimony was added, and the mixture was 
treated as before. 
The antimony, in this mass, was in the proportion of only 
half a grain in each ounce ; but the ingot was completely brittle, 
and the fracture still shewed a close grain, although the me- 
tallic lustre now began to be more apparent. 
Experiment vi. 
The two ounces of the metal formed by the preceding expe- 
riment, 'Were added to two ounces of gold made standard by 
fine copper. 
The proportion of antimony, in this experiment, could at most 
be estimated only at £ of a grain in the ounce ; but, as it may be 
supposed that, by the repeated meltings, some of the antimony 
had been volatilized, it probably was in a less proportion. 
The ingot formed by this experiment was, in colour, and in 
other properties, very like that of Exper. v. It was, however, in a 
