Nickel is a chemical element with symbol Ni and atomic number 28. The most common oxidation state of nickel is +2, but compounds of Ni (0), Ni (I), and Ni (III) are well known. It is found in various salts like Nickel chloride, Nickel nitrate and Nickel carbonate as Ni (II) ion. Nickel ions are precipitated as their sulphides by passing hydrogen sulphide gas through their solution. Nickel (II) ions react with dimethylglyoxime to form bright rose-red coloured Nickel-Dimethylglyoxime complex and they react with excess of NaOH and bromine water to form a black precipitate of Nickelic hydroxide.
This video explains how to test for the presence of nickel ion in a given salt.