If the button is too large for cupellation, or if it is hard, it may be scorified either alone or mixed with test lead before cupellation.
Under the most favourable conditions there is a slight loss of gold and silver in the fusion, the scorification and the cupellation, both by absorption in the slag and by actual volatilization and absorption in the cupel.
The process of cupellation is briefly as follows: - The gold alloy is fused with a quantity of lead, and a little silver if silver is already present.
Cupellation brings up the gold to about 900 fine.
Thus, while cupellation still furnishes the only means for the final separation of lead and silver, it has become an auxiliary process to the two methods of concentration given.