Abstract: The invention provides a method of, and apparatus for, treating sewage flowing through a sewer, wherein an oxygenating gas is introduced under pressure into the sewage and is dissolved therein and the thus oxygenated sewage is contact with a matrix of solid material carrying micro-organisms effective to reduce the Biochemical Oxygen Demand of the sewage, the matrix extending across a region inside the sewer. The treatment may be performed in a gravity sewer or in a rising or pumping sewer.

Abstract: An element for an electrically-energized vaporizer for liquid, including a body of electro-conductive material that has one major face defining a liquid inlet and a second major face defining a vapor outlet. The body is both thermally and chemically stable and is permeable by a liquid to be vaporized. The body is electrically energizable to heat and vaporize liquid as it flows from the liquid inlet face to the vapor outlet face. A plurality of blind recesses in the body are open to the vapor outlet face for providing effective escape routes for earliest produced vapor in the body whereby the entrainment of liquid in vapor issuing from the vapor outlet face is reduced.

Abstract: A process for producing powdered metal which comprises taking metal swarf, removing oil and grease from the swarf, cooling the swarf to a temperature below -20.degree. C and milling the cooled swarf to form powder.

Abstract: Apparatus which may be mounted upon a lay barge to weld an end of a pipe spool to an end of a pipeline used under water, includes a stand fixed to the pipeline to support and secure its outer end, a pipe spool support which may hold a spool in coaxial relationship with the pipeline and with one end abutting the outer end of the pipeline, a laser positioned to direct a beam of coherent radiation along the axis of the pipeline, a reflection system including a mirror mounted for movement through an arc of 360.degree. in the path of the laser beam to reflect that beam radially on the abutting ends of the pipeline and pipe spool, and a laser energy source for generating a beam of sufficient intensity to weld together the abutting ends of the pipeline and the pipe spool.

Abstract: A heat-sensitive liquid is dried and purified, by the degassing of sorbed gases, by means of a permeable electric heater, through which the liquid is passed, the liquid flowing first through a permeable liner presenting a flow impedance such that the degassing of the water vapour and gaseous impurities becomes significant only after the liquid has entered the body of the heater element.

Abstract: A gas laser including a discharge tube containing a gas mixture, the discharge tube having one or more inlets and an outlet, in which a reaction vessel is in communication with said outlet and with the inlet of a vacuum pump, and in which the outlet of the vacuum pump is in communication with the or each inlet of the discharge tube.

Abstract: A high-speed rotary vacuum pump has a compression chamber which is spaced from the walls of a housing by at least one body of acoustic insulation material which acts to absorb noise, to position the chamber with respect to the housing, and to form a fluid-tight seal between the chamber and the housing in the region where the rotary drive shaft of the pump projects from the compression chamber. The drive shaft and the gas inlet and outlet ducts are also acoustically insulated.

Abstract: A triggering device intended to be actuated upon being immersed in water uses a force-transmitting member of variable length in the form of an array of collapsible struts restrained from folding, and hence triggering the device by at least one tensile member of which the strength reduces greatly when wetted.