NOVELTY - A gas dissolving apparatus comprising a chamber external to a saturation tank and connected to the tank via a liquid outlet of the tank, is new. Chamber is provided with orifices through which liquid containing dissolved gas from the saturation tank can be released into a region external the chamber.    USE - The apparatus is used for dissolving gases in liquids (e.g. water), by passing first portion of liquid containing dissolved gas into chamber with orifices, and discharging the first portion containing dissolved gas in second liquid portion to form microbubbles of the gas (claimed). It can be used in oxygenation and ozonation of municipal, industrial, residential and environmental water supplies, bulk gas exchange and control in industrial and biotechnological processes, and applications to manufacturing, distribution and control of nanoparticles and related technologies. It can be applied for oxygenation and/or ozonation treatment of rivers, streams, and ponds in natural, municipal, or industrial settings.    ADVANTAGE - The invention provides a simplified, low cost manner for rapidly increasing the dissolved gas levels in a liquid. It is portable and can be deployed at remote locations using a standard gas-powered generator as a source of power. It provides a mechanism for more accurately dosing treatment waters for intensive mariculture and aquaculture water treatment, and for industrial disinfection. It can improve ozonation efficiency.    DETAILED DESCRIPTION - A gas dissolving apparatus comprising:    (a) a saturation tank (2) comprising a pressure vessel for containing the liquid and providing a regulated gas head space above the liquid, at least one liquid spray nozzle (20) that permits passage of liquid into the pressure vessel (14), and an outlet for the liquid (16);    (b) liquid pumping mechanism (4) in fluid communication with the liquid spray nozzle;    (c) a source (12) of the gas in communication with the regulated gas head space (18) of the saturation tank; and    (d) a chamber (24) external the saturation tank and connected to the tank via the liquid outlet (22).    Chamber is provided with orifices through which liquid containing dissolved gas from the saturation tank can be released into a region external the chamber.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram of treatment of a natural stream with a generic gas.    Saturation tank (2)    Liquid pumping mechanism (4)    Stream (6)    Source of gas (12)    Pressure vessel (14)    Liquid (16)    Gas head space (18)    Spray nozzle (20)    Outlet (22)    Chamber (24)    Microbubbles (28)