quartation
/kwɔːˈteɪʃn/Metallurgy
noun
The addition of silver to a mixture of gold and silver until the proportions are about one to three, at which point it becomes possible to remove all the silver using nitric acid.
Origin
Early 17th century; earliest use found in John Woodall (1570–1643), surgeon. From post-classical Latin quartation-, quartatio from classical Latin quartus fourth + -ātiō.