Abstract: A method of and apparatus is disclosed for water desalination including steps of transferring water vapor from salt-water in a vaporization zone 7, via a water vapor transfer zone 12, to a condensation zone 11, and condensing the water vapor into fresh-water. The water vapor transfer zone 12 is maintained substantially free of any gas other than water vapor. Heat is supplied to the vaporization zone 7 and extracted from the condensation zone 11, at relative rates such that there is a net transfer of water from the vaporization zone to the condensation zone. Also disclosed is a method of and apparatus for degassing salt water using at least two degassing chambers 17A, 17B each provided with a valved vent 47 and a valved inlet 21,29,90,91, with a valved pipe circuit 17a, 72-82,85-87, having a pump 71.

Abstract: A method for measuring the dew point temperature of a moist gas in which a flow of moist gas (A) is passed over a surface (2); a moisture sensor (5) is positioned in the flow of gas downstream of the surface (2); cooling is applied to the surface; the moisture content (M) of the gas downstream of the surface (2) is monitored; and the temperature of the surface (2) is measured, the temperature which is measured being controlled by the detection of a decrease in moisture content due to moisture condensation from the moist gas at the dew point temperature (T.sub.D). An apparatus for carrying out the method is also described. The surface (2) may be a layer of heat-conducting material in contact with a heat pump (3) or the surface may be part of the wall of a coiled tube (40).