The acidosis that occurs during clinical anaesthesia was formerly thought to be metabolic in origin because of inefficient carbohydrate breakdown in the unconscious state (Van Slyke, Austin, and Cullen, 1922). More recent authors (Taylor and Roos, 1950; Beecher and Murphy, 1950) have suggested that the acidosis is respiratory, due to defective ventilation, and the present work was undertaken to...