Abstract: A rearwardly and downwardly opening mask shell is provided for positioning about and over the nose and mouth face areas of a patient in a manner such that the mask shell seals rearwardly against the face of the patient and opens downwardly from the mouth area of the patient.

Abstract: A closed vertical mixing chamber is defined above a predetermined plan area of a body of water and an upright tubular member including open upper and lower ends is supported over a central zone of the area spaced slightly above the water level. Structure is provided defining a closed inlet chamber above lower end of the tubular member and about the latter into which gas to be humidified is admitted. The gas is discharged downwardly from the inlet chamber about the lower end of the tubular member toward the water level and at locations spaced outwardly from and about the tubular and electro-acoustical transducer structure is operatively associated with the water in the zone for generating a column of water projecting upwardly above the level and having finely divided particles of water emanating therefrom. The gas moves inwardly over the surface of the water toward the water column and thereafter upwardly into the tubular member about the water column.