1901. ------. [KÖLBEL, H.] (Steinkohlen-Bergwerk "Rheinpreussen"). [Lubricating Oil.] German Patent 709,667, July 17, 1941 (Cl. 12 o-1.01). Chem. Abs., vol. 37, 1943, p. 3926.

Tar products are condensed with unsaturated or chlorinated paraffin hydrocarbons using AlCl₃ or activated Al as catalyst. The tar products are pretreated with the AlCl₃ double compounds produced during the condensation reaction.