NOVELTY - The first and second coolants are compressed and cooled in a mixture, before being separated into a first fraction (4) containing the first less volatile fluid cooling to the first temperature and a second fraction (5) containing the second more volatile fluid cooling to the second temperature. The two coolants separate the main gas at different temperatures, giving two separation products    USE - Recovery of ethane contained in a gas under pressure containing methane and hydrocarbons with two or more carbon atoms (claimed).    ADVANTAGE - Higher yield by using multiple cooling cycles, but reduced cost because the compression and cooling of the coolant is done together    DETAILED DESCRIPTION - Recovery of ethane from a gas under pressure (1) containing methane and hydrocarbons with two or more carbon atoms, using a refrigerant cycle in which a first relatively less volatile coolant (2) is compressed, cooled and expanded to cool the gas under pressure.    This separates out the first separation products at a relatively high temperature.    A second relatively more volatile coolant (3) is compressed, cooled and expanded to cool the gas under pressure, separating second separation products at a relatively low temperature.    The first and second coolants are compressed and cooled in a mixture, before being separated into a first fraction (4) containing the first less volatile fluid cooling to the first temperature and a second fraction (5) containing the second more volatile fluid cooling to the second temperature.    The first fraction is cooled in a first exchanger (E1), expanded to give a first expanded fraction (6) and reheated in the first exchanger before being introduced into the low pressure stage (7) of a compressor (K1).    The second fraction is cooled in the first exchanger and then a second exchanger (E2), expanded and then reheated in the second exchanger before being mixed with the expanded first fraction.    A third fraction (8) is extracted from the first fraction after it is cooled in the first exchanger. This third fraction is expanded and reheated I the first exchanger to feed a fourth expanded and reheated fraction (9) which is introduced into the medium pressure stage (10) of the compressor (K1).    A fifth fraction (11) is extracted from the fluid during its compression in the compressor at a medium pressure slightly above that of the fourth fraction and is cooled and expanded to the same pressure as the fourth fraction before being mixed with it. The first and second coolants are used in a mixture with a third coolant (12).    The coolants are methane, ethylene and propane. Gas enriched with methane obtained by such a process. Product enriched with ethane obtained by such a process.    Product enriched with hydrocarbons with two or more carbon atoms obtained by such a process.    An INDEPENDENT CLAIM is also included for installation for carrying out the above process, containing means of compressing, cooling and expanding two or more coolants to different temperatures where the compression and cooling are done as a mixture and the coolants are then separated.    DESCRIPTION OF DRAWING(S) - Schematic diagram of proposed process    Gas under pressure (1)    First coolant (2)    Second coolant (3)    First fraction (4)    Second fraction (5)    Low pressure stage (7)    Third fraction (8)    Fourth fraction (9)    Medium pressure stage (10)    Fifth fraction (11)    Third coolant (12)    First exchanger (E1)    Second exchanger (E2)    Compressor (K1)