Abstract: A method for the partial or total separation by extractive distillation of C.sub.1 to C.sub.3 clorinated aliphatic hydrocarbons from mixtures of at least two such chlorinated hydrocarbons. The mixture of the chlorinated hydrocarbons is distilled in the presence of one or more other organic compounds having a boiling temperature higher than the substances to be separated, and selected from the group comprising saturated polyols, ethylene carbonate, propylene carbonate, dimethyl formamide, furfural, N-methylpyrrolidone, cyclohexanone, dimethylsulfoxide and, preferably, sulfolane and alkylsulfolanes in which the alkyl group is C.sub.1 or C.sub.2 ; use of this method for the separation of mixtures containing or essentially consisting of trichlorethylene and 1,2-dichloroethane.

Abstract: A process for the manufacture of alkali metal polyphosphates having a predetermined crystalline form, in which a mixture of alkali metal orthophosphates having a molar ratio of alkali metal oxide to phosphoric anhydride between 1 and 2 is first granulated, the resulting granules are dried and then are subjected to thermal treatment in the presence of aqueous vapor.

Abstract: A method of condensing and recovering phthalic anhydride in dilute concentration in gases discharged from reactors. The method comprises condensing the anhydride on a solid granular carrier moving in a pneumatic conveyor, separating the condensate from its carrier and cooling the said carried in a fluidized bed for recycling it. The method is also application to the condensation of other sublimable substances.