Abstract: A rotary piston internal combustion engine, includes a common housing; a stationary hollow hub; two rotary piston systems in the housing, each system including at least one piston rotor having partial cylindrical areas and front areas, the second rotary piston system including two piston rotors revolving symmetrically about a common axis and about the hub; bearing means for mounting the two rotary piston systems on parallel axes in the housing such that the piston rotors mesh with one another during opposite rotation of the two rotary piston systems, paths of movement of the piston rotors are annular and overlap one another in a penetration region of the housing, the partial cylindrical areas of each piston rotor of the first rotary piston system, during rotation thereof, forming a sealing gap of great depth alternately with the housing, and with the second rotary piston system or the hollow hub, and the front ends of the piston rotors of the second rotary piston system working together with front ends of at

Abstract: A method for separating a mixture of reaction products produced in the catalytic etherification of a lower isoolefin with methanol wherein said reaction product comprises a mixture of ether, methanol, unreacted hydrocarbon and tertiary alcohol which comprises adding water to said reaction product to form a hydrocarbon phase containing said ether and an aqueous phase containing methanol and a tertiary alcohol, separating said hydrocarbon phase to recover a methyltertiary alkyl ether, introducing said alcohol-containing aqueous phase into a distillation column to separate a methanol fraction overhead, withdrawing a side stream rich in tertiary alcohol from said distillation column, stripping this side stream in a stripping column to separate a second methanol fraction overhead and a tertiary alcohol bottoms fraction and recycling the methanol overhead fraction from the stripping column to the upper part of the distillation column and recycling the overhead methanol fraction from the distillation column to the f