Prepd by mixing a soln of a zinc salt and potassium selenide: Berzelius, cited in Mellor's 10, 776 (1930); by passing selenium vapor over zinc heated in vacuo: Moser, Doctor, Z. Anorg. Chem. 118, 284 (1921); by passing H2Se into a methanol soln of zinc acetate: Nitsche, US 2805917 (1957 to du Pont); from ZnSe.N2H4 (zinc selenide hydrazinate): Conn et al., US 3014779 (1961 to Merck & Co.).