Chemical elements
    Physical Properties
      Nickel Fluoride
      Nickel Dichloride
      Double Nickel Chlorides
      Nickel Dibromide
      Nickel Di-iodide
      Nickel Chlorate
      Nickel Perchlorate
      Nickel Bromate
      Nickel Iodate
      Tri-nickel Suboxide
      Nickel Suboxide
      Nickel Monoxide
      Nickel Dihydroxide
      Nickelo-nickelic Oxide
      Nickel Dioxide
      Nickel Subsulphide
      Nickel Monosulphide
      Nickel Sesquisulphide
      Tri-nickel Tetrasulphide
      Nickel Disulphide
      Nickel Tetrasulphide
      Nickel Sulphite
      Nickel Thiosulphate
      Nickel Dithionate
      Nickel Sulphate
      Nickel Subselenide
      Nickel Selenide
      Nickel Sesquiselenide
      Nickel Selenite
      Nickel Sesquitelluride
      Nickel Tellurite
      Nickel Chromate
      Nickel Dichromate
      Double Nickel Chromates
      Nickel Molybdate
      Nickel Nitride
      Nickel Azoimide
      Nickel Nitrite
      Nickel Nitrate
      Di-nickel Phosphide
      Nickel Sesquiphosphide
      Nickel Diphosphide
      Nickel Triphosphide
      Nickel Hypophosphite
      Nickel Phosphite
      Nickel Metaphosphate
      Nickel Orthophosphate
      Nickel Pyrophosphate
      Nickel Thio-orthophosphate
      Nickel Thiopyrophosphite
      Nickel Thiopyrophosphate
      Tri-nickel Diarsenide
      Nickel Arsenide
      Nickel Diarsenide
      Nickel Arsenite
      Nickel Orthoarsenate
      Nickel Antimonide
      Nickel Antimonate
      Nickel Thioantimonite
      Nickel Vanadate
      Nickel Carbide
      Nickel Tetracarbonyl
      Nickel Carbonate
      Nickel Monocyanide
      Nickel Cyanide
      Nickel Thiocyanate
      Nickel Thiocarbonate Hexammoniate
      Nickel Subsilicide
      Nickel Orthosilicate
      Nickel Monoboride
      Nickel Borates
    PDB 1a5n-1g2a
    PDB 1g3v-1mn0
    PDB 1mro-1s9b
    PDB 1scr-1xmk
    PDB 1xu1-2cg5
    PDB 2cqz-2jih
    PDB 2jk8-2v4b
    PDB 2vbq-3c2q
    PDB 3c6c-3h85
    PDB 3hdp-3kvb
    PDB 3l1m-3o00
    PDB 3o01-4ubp
    PDB 8icl-9ant

Nickel Monosulphide, NiS

Nickel Monosulphide, NiS, occurs in nature as the mineral millerite. It may be prepared by heating nickel and sulphur together or by the action of hydrogen sulphide on nickel heated to redness. As obtained in either of these ways it is a bronze-yellow mass, insoluble in hydrochloric or sulphuric acid, but soluble in nitric acid and in aqua regia. Its density is 4.60, and specific heat 0.1248. Heated to redness in hydrogen, the sulphide remains unchanged, but in oxygen a basic sulphate is produced. Chlorine and water vapour attack it but slowly. The sulphide is also obtained as a grey amorphous mass by treating a solution of nickel sulphate at 80° C. with hydrogen sulphide under pressure.

It has been prepared in the crystalline form similar to the mineral by heating solutions of potassium sulphide and nickel chloride to 160-180° C. in a sealed tube. Ammonium thiocyanate and nickel chloride solutions under similar conditions produce the same sulphide.

Nickel sulphide may also be obtained by precipitation from solutions of nickel salts. It then occurs in three different polymeric forms, α, β, and γ, according to circumstances. Of these, α-nickel sulphide is soluble in dilute mineral acids, even with as low a concentration as 0.01 normal. β-nickel sulphide dissolves easily in 2-normal hydrogen chloride, whilst γ-nickel sulphide is insoluble unless oxidising agents are present.

When dilute reagents are used - for example, nickel sulphate and ammonium sulphide in dilute aqueous solution - probably the α compound is first formed, and then, when the solubility of this substance is exceeded, a precipitate separates out which subsequently more or less completely polymerises to the β and γ forms. This suffices to explain the well-known fact in qualitative analysis that whilst nickel sulphide cannot be precipitated in acid solution by hydrogen sulphide, yet when once precipitated in alkaline solution it is very difficult to dissolve again completely in dilute mineral acid.

The three varieties of nickel sulphide can be obtained in more or less pure forms separately as follow:

When dilute solutions of nickel sulphate and an alkali sulphide are slowly mixed at the ordinary temperature in the absence of air, 85 per cent, of the precipitate consists of α-NiS. This sulphide is stable in the absence of air if kept in contact with pure water. In contact with solutions that dissolve it to a slight extent it yields the β and γ varieties. β-nickel sulphide results, mixed with a little γ, when a solution of nickel acetate acidified with acetic acid is treated with hydrogen sulphide. Boiling with acetic acid converts it into the γ-form. It appears to be crystalline, γ-nickel sulphide may be obtained in a pure crystalline condition by boiling the mixed sulphides with 2-normal hydrochloric acid.

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