Difficulty fusible or infusible solids of high molecular weight, with or without lubricating oils, are obtained by dehydrogenating solid or semisolid paraffin hydrocarbons, or mixtures consisting mainly thereof, and treating the products with a condensing or polymerizing agent; for example, AlCl3, ZnCl2 or BF3. The dehydrogenation may be effected by introducing substituents such as Cl, O2, or S into the starting materials and then removing the substituents, suitably in the form of their H compounds. The solid products are useful as insulating materials or components of rubber mixtures. Gives examples and numerous details. Addition to German Patent 556,309 (abs. 2657).