Iron Subsulphides

Several supposedly subsulphides of iron have been described from time to time, namely Fe₂S, and Fe₄S₃. The last named is produced when iron is heated in an atmosphere of carbon disulphide vapour, at 1300° to 1400° C., and allowed to cool in the di-sulphide vapour. It is a crystalline body of density 6.96, and soluble in dilute mineral acids evolving hydrogen sulphide and hydrogen. It does not alter when exposed to air, and is oxidised only with difficulty.