Where purity is required, foil is better.
The gold is placed in three or four times its own weight of the above acids.

For this purpose, an evaporating dish is best (a common saucer will do); a moderate heat may be applied to favor the action.

The mixture should be stirred often with a glass rod; care should be observed not to apply too much heat, for at a temperature of about 300 deg.

the chlorine would be expelled and leave a metallic precipitate, which would require re-dissolving.

Acid may at any time be added if necessary to dissolve the gold, but it is advisable to add as little excess as possible, as it would require more time to evaporate.