defining structure at least a portion of which is a thermally conductive material this flow path defining structure defines a first flow path for the exhaled breath gases and defines a separate second flow path for the coolant fluid adjacent the first flow path the conduits 268 168 or 68 may be of any suitable material which can transfer sufficient heat to the coolant fluid to maintain the temperature within the scrubbing substance 215 115 or 15 below a desired maximum value in contemplated designs for the embodiments illustrated in fig8 13 each tube is fabricated from steel and has a nominal diameter of about 1 inch with any of the above described embodiments when the scrubbing substance is exhausted or when it is otherwise desired to replace the scrubbing substance the apparatus can be opened so that the original scrubbing substance or what remains can be removed the apparatus is refilled with a new charge of the scrubbing substance and the apparatus is then returned to the closed operating condition with the novel apparatus and process of the present invention the temperature of the interior of the scrubber enclosure can be controlled and maintained below the point where the heat buildup becomes a problem the system of the present invention is readily adapted for use with a variety of anesthesia machines which employ scrubbing substances the apparatus is relatively easy to operate and maintain and the apparatus is very effective in maintaining desired temperatures within the scrubbing substance so as to provide an even greater safety margin when using anesthetics that might degrade at elevated temperatures it will be readily apparent from the foregoing detailed description of the invention and from the illustrations thereof that numerous variations and modifications may be effected without departing from the true spirit and.