Abstract: The present invention is a oxygen generating device which comprises: a container having a mouth and a neck surrounding the mouth; a tank which has an annual flange for establishing a gas tight seal between the tank and the neck; a dome assembly which is engageable with the neck and extends upwardly to define a dome chamber above the neck; and means for permitting oxygen generated in the tank to flow into the dome chamber by bubbling through a liquid contained in the dome base; the dome base having an outlet connection through which oxygen can leave the chamber and where at least part of the dome is transparent so as to render the inside thereof visible from the outside of the dome.