Nickel sulfate with or without water, hexahydrate and heptahydrate three. Commodities are mostly hexahydrate, there are α- type and β- type two variants, the former is blue tetragonal crystal, the latter is green monoclinic crystal. Six crystals are lost when heated to 103°C. Soluble in water, slightly soluble in ethanol, methanol, its aqueous solution is acidic, slightly soluble in acid, ammonia water, toxic. Mainly used in electroplating industry, is the main nickel salt for electroplating nickel and chemical nickel, but also the source of metal nickel ions, can dissociate nickel ions and sulfate ions in the electroplating process.