A technical film (part of a series) apparently aimed at the inexperienced anaesthetist. This video explains the principles of the carbon dioxide absorption technique and demonstrates the two methods in use: single-phase absorption and closed-circuit or two-phase absorption. Firstly the principle of absorption is illustrated using diagrams. Next the equipment is shown being prepared; a canister is shown. An anaesthetist is shown preparing a patient; nitrous oxide and ether are discharged into the breathing aparatus. The anaesthetist has to observe the patient's breathing bag carefully to monitor the patient's air supply. The methodology for using closed-circuit anaesthesia is more complex and requires the clinician to calibrate the machinery carefully; the advantage of this methodology is that a suitable level of anaesthesia can be maintained. Ends suddenly; no credits.