132.    --------------. [BAHR, H. A., AND BAHR, T.] [Reactions of Nickel Carbide (Ni₃C) Prepared at Low Temperatures.]  Ber. deut. chem. Gesell., vol. 63B, 1930, pp. 99-102; Chem. Abs., vol. 24, 1930, p. 1812.

                  Finely powdered Ni₃C, resulting from the action of CO on Ni at low temperatures, is pyrophoric.  This property is destroyed by displacing the adsorbed CO with pure N₂ at 250°.  The stabilized carbide may be heated to 110° without oxidation.  The activity toward CO and H₂ is also decreased by the stabilization.  Ni₃C absorbs moisture from the air.  It has a specific gravity of 7.97 and is slightly magnetic.  Its heat of formation is –9.2=0.8 kcal.  It begins to decompose into its elements when heated to about 400°.  With H₂ at 180°-250°, CH₄ and C₂H₆ are formed in the ratio of 10:1.  In gaseous-hydrogenation reactions with Ni as a catalyst, the primary hydrogenation is evidently much faster than the secondary polymerization reaction.  An increase in pressure increases the latter.  At 300° H₂O vapor acts on the carbide with the production of H₂ and CH₄.  Similarly, NH₃ at 420° gives H₂, CH₄ and some C₂H₆.  H₂S yields heavy hydrocarbons as low as 240°.  HCl gas acts similarly.  Contrary to the action of Fe₃C, Ni₃C usually dissolves in acids without the liberation of free C and produces hydrocarbons of lower molecular weight than the former carbide.  In 3 N HCl, 67% of the C is converted to gaseous hydrocarbons and 33% to liquid.  In dilute HNO₃ nitro compounds of the hydrocarbons are formed.  Some free C results from the action of dilute H₂SO₄ on the carbide.