Abstract: A carburettor or other mixture generator 1 for an internal combustion engine has a mixing chamber 3 which is surrounded by a tubular wall 2 and delimited at its ends by a throttle valve 4 and a choke 5. The wall 2 is double-skinned with a water heating chamber 10 between the skins. In order to heat the wall 2 and prevent the condensation of liquid fuel upon it, water from a cooling water circuit of the engine to which the carburettor is fitted is circulated through the chamber 10 under the control of a thermally operated valve 21. Since the cooling water will no heat the carburettor until the engine itself has become heated, the carburettor is also provided with electrical heating for cold starting purposes. The chamber 10 is raised so that when the engine cooling water pump is not operating the chamber 10 is empty and the inside skin 9 of the wall 2 is made of electric resistance heating material.