quartation

CIDE DICTIONARY

quartation, n. [L. quartus the fourth: cf. F. quartation. So called because usually enough silver is added to make the amount of gold in the alloyed button about one fourth.].

 The act, process, or result (in the process of parting) of alloying a button of nearly pure gold with enough silver to reduce the fineness so as to allow acids to attack and remove all metals except the gold; -- called also inquartation. Compare Parting.  [1913 Webster]