Abstract: An internal combustion engine with charge stratification and spark ignition comprises a cylinder head having a main combustion chamber and a cavity defined by surrounding walls of the cylinder head and opening toward the main combustion chamber. An auxiliary combustion chamber is formed within a cup-shaped insert frictionally maintained in the cavity and opening away from the main combustion chamber. The cup-shaped insert is thin-walled and has an opening providing a passage connecting the main combustion chamber and the auxiliary combustion chamber and a pair of openings for receiving a fuel delivery device and an ignition device, respectively.

Abstract: Refuse, particularly of the household type, is sorted according to density by the following consecutive operations: Sifting the refuse; comminuting the oversize obtained; separating the comminuted material by a gas stream into light and heavy material fractions; separating the heavy material fraction by a liquid stream into two fractions of different density; and separating the two fractions of different density into basic components.