zinc-sulphatehttp://www.oed.com/dictionary/zinc-sulphate_n%3Ftab%3Dmeaning_and_usezinc sulphate, n.
First published 1921; not fully revised

zinc sulphatenoun

  1. 1851–
    1. 1851
      The solution of zinc-sulphate is mixed with sal-ammoniac.
      H. Watts, translation of L. Gmelin, Hand-book of Chemistry vol. V. 14
    2. 1868
      Zinc sulphate..is used..as an emetic.
      H. B. Jones & H. Watts, Fownes's Manual of Elementary Chemistry (ed. 10) 398

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

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