The chloride of a metal that is soluble in excess of ammonium hydroxide is zinc chloride.
On adding ammonium solution, in drops, the colourless solution of zinc chloride forms white gelatinous precipitate of zinc hydroxide. This hydroxide solution dissolves in excess of ammonium hydroxide and forms a complex, colourless tetramine zinc(II) chloride.
ZnCl2 + NH4OH → Zn(OH)2 + 2NH4Cl
Zn(OH)2 +2 NH4Cl + 2 NH4OH → [Zn(NH3)4]Cl2 + 4 H2O