An empty British Oxygen Company (B.O.C.) Mk. 4 carbon dioxide absorption cannister was modified for use as a vaporizer by placing a layer of flannelette bandage over the horizontal perforated septum and adding a base plate with an exit port for anaesthetic vapour. Aliquots of liquid anaesthetic were injected from a syringe through the top of the cannister and vaporised by air drawn through the cannister. Laboratory testing showed that this could be a useful way of administering inhalational anaesthesia in the absence of compressed gas supply.