the one hand but to prevent on the other hand the transfer of too great a quantity of valuable distillable organic components into the economically less favorable decomposition stage in the second process step the residues which contain the chlorinated hydrocarbons are evaporated for example in a thin film apparatus to such an extent that a mixture remains having a viscosity of 8 50 cp preferably 10 15 cp at 20 u00b0 c and at a shear velocity of 200 sec 1 the indicated values relate to measurements with a couette viscosimeter the vapors obtained in the evaporation are condensed the condensate is separated into its components by a rectifying distillation process and these components are recycled into chemical processes the condensate can also be used in a cycle type procedure for the dilution of substance mixtures to be worked up which otherwise could not be transported the 1 2 dichloroethane recovered by distillative separation can be used for example for the manufacture of vinyl chloride the other chlorinated hydrocarbons can be used for the production of perchloroethylene depending on the quantity of residues obtained the evaporation can be carried out in one or in several thin film evaporators in this connection the evaporators can not only be operated in parallel but also in a series connection the.