Mirror with inscription of "Wu Zi Deng Ke" ——The technology of tin enrichment on the surface of copper ware by liquid penetration

<正>Ming Dynasty(1368 A.D.-1644 A.D.)Diameter:10.5 cm,weight:140 g Brass"Wu Zi Deng Ke",(five sons passed the imperial examinations),is an ancient story in China,telling that all five sons of one family passed the examinations and became the Jinshi,a type of degree conferred by the ancient Chinese Imperial Examination System.This auspicious expression was commonly observed on bronze mirrors of the Ming Dynasty,