common metals, acts upon its own proper argent vive, and turns it into dross, which being separated from the metals enters into the porous matter of the cuples, that which doth not happen in tests, fixed in the fire, which that dross being separated from the metals cannot enter into, being made of an earth that is durable in the fire, the dross remaining in them, which otherwise was wont to enter into those cuples that are made of the ashes of bones, or wood. Wherefore by little and little it goes away into the cuple, _viz._ as much as the fire reduced into a Litharge, or dross, until all the Lead mixed with the Gold and Silver together with other imperfect metals mixed with it go into dross, and hide themselves in the cuple, the pure gold and silver being left in the cuple. For Lead in a plain vessel, feeling the heat from above, but beneath cold, is turned into a Litharge, which if it be in an earthen fixed vessel, the Litharge remains, and goes in a yellow transparent glass at last, if it be not mixed with other metals, as iron, copper, tin; which being mixed therewith, give to the glass a green, red, black, or white colour, according to the quantity of the metallick matter: but in a porous cuple made of ashes, the Litharge, or dross finding pores, enters into the cuple by little and little, and successively, until all the Lead be entred in, which could not be if it were not turned into Litharge. This vulgar trying is therefore nothing else but a transmutation of Lead, with the imperfect metals mixed with it, into dross, which entring into the cuple leaves in the cuple pure gold, and silver, that cannot be turned into dross by reason of their purity.