Abstract: Preparation of insecticidal, biodegradable compositions comprising mixtures of p-p'disubstituted diaryl trichloroethanes. Chloral, and appropriate substitutal benzenes are condensed, in a single step, at low temperature, e.g., -30.degree.C., using a condensing agent preferably consisting of a mixture of sulfuric acid and acetic acid.

Abstract: Refrigeration is produced by compressing a multi-component refrigerant to a high pressure, cooling the high pressure refrigerant to produce a refrigerant having a vapor phase and a liquid phase, separating the two phase refrigerant into a vapor phase and a liquid phase, passing the refrigerant vapor phase through heat exchanger means to cool and condense it to a liquid, expanding the so-formed cold stream of condensed liquid to a colder low pressure stream, passing it back through the heat exchanger means to provide low temperature refrigeration thereto to cool the high pressure vapor stream fed therethrough and have extra refrigeration for removing heat from a product, and expanding the separated high pressure liquid phase to a low pressure cool stream, feeding the low pressure cool stream to an intermediate point in the heat exchanger means, combining said stream with the cold low pressure stream formed from the vapor removed from the vessel to provide warm temperature refrigeration to remove heat from the