Put about 2cm3 of MgCl2 CaCl2 AlCl3 NaCl KCl FeSO4 Fe2SO4 3 CuSO4 ZnSO4NH4NO3 PbNO3 2 BaNO3 2 each into separate test tubes Add three drops of 2M sodium hydroxide solution then excess 23 the length of a standard test tube