zinc-amalgamhttp://www.oed.com/dictionary/zinc-amalgam_n%3Ftab%3Dmeaning_and_usezinc amalgam, n.
First published 1921; not fully revised

zinc amalgamnoun

  1. 1839–
    1. 1839
      Dilute muriatic acid, containing some wine stone and zinc amalgam.
      A. Ure, Dictionary of Arts 166

Originally published as part of the entry for zinc, n.

zinc, n. was first published in 1921; not fully revised.