zinc-salthttp://www.oed.com/dictionary/zinc-salt_n%3Ftab%3Dmeaning_and_usezinc salt, n.
First published 1921; not fully revised

zinc saltnoun

  1. 1841–
    1. 1841
      When hydroferrocyanic acid is added to a soluble zinc-salt.
      W. T. Brande, Manual of Chemistry (ed. 5) 777

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

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