1270.    GROSS, H., AND GRODDE, K. H.  [Structure of Solid Hydrocarbons as Basis for Classification.]  Oel u. Kohle, Erdoel, Teer, vol. 38, 1942, pp. 419-431; Chem. Abs., vol. 37, 1943, p. 5693.

        This study of the physical constants of the solid-paraffin hydrocarbons shows that, for a given molecular weight, branching of the chain causes lowering of the solidification point, and that presence of rings causes, in addition, an increase in density.  In this way a “ring val.” (indicating presence of ring paraffins) and an “asymmetry val.” (indicating branching of the chains) can be deduced.  Heterogeneous mixtures of solid hydrocarbons were examined by separating them according to molecular weight by fractional distillation and according to their asymmetry by fractional crystallization from solutions in (CH₂Cl)₂.  Of the products examined, the Fischer-Tropsch synthesis product was a mixture of normal and isoparaffins, that is, of aliphatic nature, while the solid hydrocarbons from petroleum and brown-coal tars contained varying quantities of ring paraffins with different numbers of rings per molecule.  The result suggests a classification of solid hydrocarbons on the basis of their composition, solidification points, and ceresin character.