Nickel Subsulphide, Ni₂S

Nickel Subsulphide, Ni₂S, is stated to be obtained by heating nickel monosulphide in an electric furnace, and by reduction of nickel sulphate with hydrogen or sulphur at red heat; but Bornemann, from a consideration of the freezing-point curve of nickel sulphides, concludes that the subsulphide is not a separate chemical entity, but a eutectic mixture.