3436.    TRAVERS, A., AND DIEBOLD, R.  [Decomposition of Pure Cementite by Acids.]  Compt. rend., vol. 205, 1937, pp. 916-918; Chem. Abs., vol. 32, 1938, p. 895.

        Large proportion, sometimes 78% of C from cementite is liberated in the free state, while of the hydrocarbons evolved, paraffins (CH₄, C₂H₆) form only 3-4%, the rest being olefins (C₃H₆ sometimes 50%).  It is suggested, therefore, that cementite is (Fe₃C)_n with n not less than 3, and that the linkage:  C:C: is present, and that the H replacing the Fe on solution does not produce more than a small amount of saturated hydrocarbons on account of the absence of any catalyst.  This view is shown to be consonant with several reactions and to explain the impossibility of determining actions and to explain the impossibility of determining (Fe₃C)_n by selective solution of Fe.  The C separated is remarkably absorbent.