Abstract: An inhalation tower comprises two columns forming two concentric ducts each made up of segments fitted into one another. The segments forming the outer duct have an external annular portion at one end and an internal annular portion at the other end, the axial height of the latter being less than the height of the external annular portion, so as to leave a space for receiving a plate. The internal duct has radial connecting ducts which open into the end of a cylindrical cavity formed in the external segment, a space being reserved between the connecting duct and the diameter of an opening through the end of the cavity. The cavity is adapted to receive an inhalation chamber borne by the tray.