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The presence of ferrous sulfide as a visible black precipitate in the growth medium peptone iron agar can be used to distinguish between microorganisms that produce the cysteine metabolizing enzyme cysteine desulfhydrase and those that do not. Peptone iron agar contains the amino acid cysteine and a chemical indicator, ferric citrate. The catalysis of cysteine releases hydrogen sulfide gas that reacts with the ferric citrate to produce ferrous sulfide.
Uses of Ferrous
Sulphide
Ferrous Sulfide or Iron Sulphide sticks are widely used as a laboratory
chemical for the preparation of Hydrogen Sulphide gas, by famous KIPP'S apparatus when comes in contact with dilute mineral
acids.
In foundries, during electric melting, residual sulphur level
decreases due to cleaner melting practices and the use of low
sulphur steel scrap. It is found that iron does not readily
respond to inoculants if Sulphur is below 0.04%. Then it is
necessary to re-sulphurize by using Ferrous Sulphide or Iron
Sulfide .
In Alloy And Stainless Steel Industries To Control Hydrogen
Embrittlement It is very convenient and economic to use Ferrous
Sulphide or Iron Sulfide for re-sulphurization in these steels to hold the right
level of 'S' and ensuring not to drop 'S' level.
Iron Sulphide is used as a
re-sulphurizing agent in the
production of carbon, alloy and stainless types of free cutting
steels. It acts as an alloying agent to improve machine ability
of steel castings which are used to manufacture various steel
components.
Sulphur in form of Ferrous Sulphide or Iron Sulfide is added along with FeSi & FeMn to increase the 'S' contents of electrically melted iron. Addition of FeS influences white iron formation and obtain 'S' contents approximately 0.15%
The Purification Of Crude Phosphoric Acid Ferrous Sulphide or Iron Sulfide is used in cake form as a reducing agent to remove heavy metal impurities from phosphoric acid.
Elemental Sulphur has very low melting point and its tendency to float on the surface of molten metal resulting in the release of Sulphur dioxide, an undesirable gas which pollutes the working environment. Moreover, low melting eutectic brittle compounds form along the grain boundaries and mechanical properties are deteriorated. Hence Ferrous Sulphide or Iron Sulfide and not Sulphur is used for increasing sulphur content of Iron and Steel.