6o Mr. Hatchett's Experiments on the various Alloys , 
grains of pure metallic cobalt were added, and, being well 
melted and mixed, the whole was poured into a dry cupel. 
The external colour of this metal was a dull yellow ; it was 
very brittle, and the fracture appeared of a pale yellow, with an 
earthy grain. 
Experiment n. 
To eighteen pennyweights and ten grains of the fine gold, 
alloyed with 19 grains of pure copper, were added 19 grains of 
metallic cobalt, which being perfectly melted and mixed, the 
whole was treated as before. 
The metallic button, externally, appeared of a pale yellow, 
slightly tinged with gray ; it was brittle, and shewed a fine- 
grained earthy fracture. 
Experiment in. 
Eighteen pennyweights and ten grains of the fine gold, alloyed 
with one pennyweight and six grains of copper, being melted, 
eight grains of cobalt were added, and mixed. 
The colour of this ingot was like that of the former, but the 
yellow colour was rather deeper. It soon broke under the ham- 
mer, and the fracture was still of a fine grain, inclining to an 
earthy appearance. 
Experiment iv. 
To eighteen pennyweights and ten grains of gold, alloyed 
with one pennyweight and ten grains of copper, four grains of 
cobalt were added. The colour of this metal resembled that of 
gold made standard by copper, excepting that it was rather 
paler. This ingot was but slightly brittle. 
As the last metal began to be ductile, the experiments with 
cobalt were not continued. 
