assaying

n a small porous bowl made of bone ash used in assaying to separate precious metals from e.g

A treatise on the art of testing, as in assaying metals, etc.

The art or process of assaying or reducing ores by means of liquid reagents.

specifically, a small flat bowl-shaped cup used in the first heating in assaying, to remove the earth and gangue, and to concentrate the gold and silver in a lead button.

specifically, in assaying, to fuse so as to separate the gangue and earthy material, with borax, lead, soda, etc., thus leaving the gold and silver in a lead button; hence, to separate from, or by means of, a slag.